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Journal of Engineering for Gas Turbines and Power; https://doi.org/10.1115/1.4052425

Abstract:
Acoustic pyrometry is a widely used technique for contactless temperature measurement. It may be used in several applications, especially when high temperatures and harsh environments are involved. For instance, it has been applied to measure the temperature distribution at gas turbine outlet. This technique is based on the measurement of the time of flight of an acoustic wave through a medium. If multiple emitter-receiver couples are used, by using a computational procedure a reconstruction of a temperature map is possible. On the other hand, a full assessment of the robustness of this technique to potential errors in time of flight estimation is still missing. In this study, the impact of an inaccuracy in time of flight estimation on the reconstruction of a correct temperature map is investigated by means of a statistical approach. As a general result, it was found that when the time of flight was measured without inaccuracies, temperature estimation errors may be lowered by simply increasing the number of cells in which the estimation is performed. However, when the estimation of the time of flight is affected by errors, an optimal configuration exists that minimize the temperature estimation errors.
Journal of Engineering for Gas Turbines and Power; https://doi.org/10.1115/1.4052430

Abstract:
The paper presents measurements of performance conducted on a copper pads bearing (C-PB) and a steel-pads bearing (S-PB). Both bearings have the same geometry and differ on the pads' backing material, copper vs. steel. The journal diameter D=102 mm, and a bearing has five pads with length L=0.4D, nominal radial clearance 0.064 mm. The bearings operate at four shaft speeds ranging from 6 krpm to 14 krpm and under multiple specific loads ranging from 0.17 MPa to 2.1 MPa. At the highest load (on pad) and low speed, the S-PB static eccentricity is up to 37% higher than that for the C-PB. The oil exit temperature rise is similar for both bearings, the maximum difference reaches 6 °C. For all operating conditions, the pads' peak temperature rise, having a maximum difference of 5 °C to 16 °C, is larger for the S-PB. The S-PB produces a ~ 5% lower drag power loss than that in the C-PB. From dynamic load test results, the C-PB direct stiffness KYY (along the load direction) is up to 30% higher than the S-PB stiffness, while the difference in KXX between the C-PB and the S-PB ranges from 60% to 90%. Similar to the stiffness results, the C-PB produces larger direct damping coefficients; CYY and CXX are up to 25% and 40% larger than those for the S-PB.
Journal of Engineering for Gas Turbines and Power; https://doi.org/10.1115/1.4052426

Abstract:
The growth of renewable energy source requires reliable, durable and cheap storage technologies. In this field, the Pumped Thermal Energy Storage (PTES), is drawing some interest as it appears not to be affected by geographical limitations and use very cheap materials. PTES is less efficient than pumped hydro and batteries, but it could achieve satisfactory efficiencies, show better economic performance and be characterized by negligible environmental impacts. A PTES stores the electric energy as thermal exergy in solid packed beds, by operating two closed Brayton cycles, one for charging and the other one for discharging. Although PTES thermodynamical behavior is well understood, the interaction between the components is rarely investigated. This study investigates the impact of packed-bed behavior on turbomachines operating conditions. In this way, PTES off-design and part-load performance are estimated. A control strategy especially suited for closed Brayton cycles, i.e. the inventory control, is used to control the system. As it resulted, PTES is characterized by an excellent part-load performance, which might be a significant advantage over the competing technologies. However, the off-design operation induced by the packed-bed thermal behavior might significantly reduce the system performance and, in particular, that of the discharge phase.
Journal of Engineering for Gas Turbines and Power; https://doi.org/10.1115/1.4052424

Abstract:
Aircraft operators rely on gas path analysis techniques for monitoring the performance and health of their gas turbine engine assets. This is accomplished by analyzing discernable shifts in measurement parameters acquired from the engine. This paper reviews the founding mathematical principles of gas path analysis, including conventional approaches applied for estimating engine performance deterioration. Considerations for extending the application of gas path analysis techniques to Electrified Aircraft Propulsion (EAP) systems is also discussed, and simulated results from their application to an EAP concept comprised of turbomachinery and electrical system hardware is provided. Results are provided comparing the parameter estimation accuracy offered by taking a whole-system approach towards the problem setup versus that offered by analyzing each subsystem individually. For the latter, the importance of having accurate direct or inferred measurements of external mechanical torque loads placed upon turbomachinery shafts is emphasized.
Journal of Engineering for Gas Turbines and Power; https://doi.org/10.1115/1.4052428

Abstract:
Rolling-element bearings (REB) can develop severe damage due to skidding (slipping) between the rolling elements and bearing races. Skidding can be described as gross sliding between the bearing surfaces in relative motion and can result in significant surface distress such as smearing, especially at light loads and high rotational speeds. Under these conditions, skidding occurs between the rolling elements and the bearing races, leading to increased wear (higher friction coefficient), elevated bearing temperature, significant power losses and reduced service life of the bearing. The main objective of this study is to investigate the significance of various sensing technologies (induction, vibration, ultrasound, acoustic and optical) in detecting skidding in standard series roller bearings as well as custom-made roller bearings for aero engine applications. The bearings have a bore diameter of 60 mm and 90 mm, respectively. Jet and under race lubrication techniques have been used to supply oil to the bearings under test. The custom-made aero engine test bearing features special channels to allow under race lubrication of the rollers/races contacts as well as the cage land. The effect of radial load, rotational speed and oil flow on roller skidding have also been investigated and analyzed. Tests have been performed on a dedicated high speed experimental bearing facility and data was recorded using a commercially-available data acquisition system.
Zonghan Sun, Jie Tian, , Zhaohui Du, Hua Ouyang
Journal of Engineering for Gas Turbines and Power; https://doi.org/10.1115/1.4052429

Abstract:
A noise reduction method for axial flow fans using a short inlet duct is proposed. The pattern of noise reduction imposed by the short inlet duct on the axial flow cooling fan under variable working conditions was experimentally and numerically examined. A 2-cm inlet duct was found to reduce tonal noise. As the tip Mach number of the fan increased from 0.049 to 0.156, the reduction in the total average sound pressure level at 1 m from the fan increased from 0.8 dB(A) to 4.3 dB(A), and further achieved 4.8 dB(A) when a 1-cm inlet duct was used. The steady CFD showed that the inlet duct has little effect on the aerodynamic performance of the fan. The results of the unsteady calculation showed that the suction vortexes move upstream to weaken the interaction with the rotor blades, which significantly reduces the pulsating pressure on the blades. The SPL at the BPF contributed by the thrust force was calculated to reduce by 36 dB at a 135° observer angle, reflecting the rectification effect of the duct on the non-uniform inlet flow. The POD of the static pressure field on the blades verified that the main spatial mode is more uniformly distributed due to the duct, and energy owing to the rotor-inlet interaction decreases. A speed regulation strategy for the cooling fan with short inlet duct is proposed, which provides guidance for the application of this noise reduction method.
Journal of Offshore Mechanics and Arctic Engineering pp 1-10; https://doi.org/10.1115/1.4052421

Abstract:
Open ocean aquaculture cages became recently a promising alternative to traditional fish cage designs. The offshore environment implies larger loads on the structures and higher risk of fish loss. Floating rigid aquaculture cages with stiff nets are considered as a possible solution to cope with these new challenges. Their design process requires more advanced tools to account for the non-linear fluid-structure interaction. This paper presents a suitable numerical approach for analysing the interaction of offshore aquaculture cages and waves using Computational Fluid Dynamics. Here, a numerical wave tank accounts for the accurate propagation of the waves, and structural dynamics solutions are utilised for the cage system. Two-way coupling is enabled by accounting for the influence of the net on the fluid. The numerical model is validated against measurements for the loads on and the responses of a mobile floating fish farm in waves and current.
Published: 14 September 2021
Journal of Turbomachinery pp 1-35; https://doi.org/10.1115/1.4052419

Abstract:
Modern gas turbines present important temperature distortions in the core-engine flowpath, mainly in the form of hot and cold streaks. As they highly influence turbines performance and lifetime, the precise knowledge of the thermal field evolution through the combustor and the high-pressure turbine is fundamental. The majority of past studies investigated streaks migrations directly examining the thermal field, while a limited amount of experimental work employed approaches based on the detection of tracer gases. The latter approach provides a more detailed evaluation of the evolution and mixing of the different flows. However, the slow time response due to the employment of sampling probes and gas analysers make the investigation extremely time consuming. In this study a commercial oxygen sensor element and its excitation/detection unit were integrated into a newly developed probe to carry out local tracer gas concentration measurements exploiting the fluorescence behaviour. The paper summarizes the probe development and calibration activities, with the characterization of its accuracy for different flow conditions. Finally, two probe applications are described: firstly the probe was used to detect tracer gas concentrations on a jet flow; afterwards it was traversed on the interface plane between a non-reactive, lean combustor simulator and the NGV cascade. The probe has proven to provide accurate and reliable measurements both from a quantitative and qualitative point of view even in highly 3D flow fields typical of gas turbines conditions.
, Xianying Feng, Zhe Su, Yandong Liu, Dechen Wang
Published: 14 September 2021
Journal of Tribology pp 1-16; https://doi.org/10.1115/1.4052422

Abstract:
This paper proposes a novel dual-drive hydrostatic lead-screw system (DDHLS). The design enables a lower feed speed and a better transmission performance than the conventional hydrostatic lead screw (HLS). Considering the nut-misalignment, the lubricating mathematical model of the DDHLS is established based on the perturbation method and solved by the finite difference method. The influences of the nut-radial-displacement, the nut-tilt, and the dual-drivable design on the transmission performance of the DDHLS are researched. The results show the nut-misalignment can regularly reduce or increase the axial load capacity, the axial stiffness coefficient, and the axial damping coefficient. Significantly, the dual-drivable design can improve the axial load capacity and the axial stiffness coefficient while hardly affects the axial damping coefficient.
Journal of Engineering for Gas Turbines and Power; https://doi.org/10.1115/1.4052427

Abstract:
Geometric mistuning models formulated from a component mode synthesis methods often require the calculation of component modes, particularly constraint and fixed interface normal modes, during substructuring. For Integrally Bladed Rotors, these calculations are required for each sector. This paper proposes methods that reuse information garnered from solving the constraint modes of a single sector on the remaining sectors to reduce memory requirements and solution times. A mesh metamorphosis tool is used to ensure finite element models match geometry obtained from a 3D optical scanner. This tool also produces a common mesh pattern from sector-to-sector. This is exploited to produce common permutation matrices and symbolic factorizations of sector stiffness matrices that are proposed for reuse in solving subsequent constraint modes. Furthermore, a drop tolerance is introduced to remove small values during constraint mode calculation to reduce memory requirements. It is proposed to reuse this dropping pattern produced from a single sector on the remaining sectors. Approaches are then extended to a parallel processing scheme to propose effective matrix partitioning methods. Finally, information gathered during the constraint mode calculations are reused during the solution of the fixed interface normal modes to improve solution time. Results show reusing permutation matrices and symbolic factorizations from sector-to-sector improves solution time and introduces no error. Using a drop tolerance is shown to reduce storage requirements of a constraint mode matrix, while reusing the dropping pattern introduces minimal error. Similarly, reusing constraint mode information in calculating normal modes greatly improves the performance.
Published: 13 September 2021
Journal of Turbomachinery pp 1-11; https://doi.org/10.1115/1.4052409

Abstract:
Variable inlet guide vanes (VIGV) are the main control element to adjust the flow rate of industrial centrifugal compressors by customized pre-swirl in the inlet plane of the impeller. The efficient working range of VIGVs is however restricted due to open flow separation occurring at critical stagger angles. In order to overcome the narrow limitations of current blade geometries and to enhance the operating range of the compressor, split blades consisting of a separate front and tail blade segment proved to be particularly promising in previous linear-cascade measurements. Each blade segment is thereby individually staggered. This enables a gradual flow deflection along the chord length. Secondary flow losses, however, were not considered in the previous investigations with linear-cascades. To highlight the potential of the split blade concept under more application-oriented conditions including all relevant flow effects, highly resolved field measurements were conducted in the wake of annular VIGVs. Four different blade configurations, a customary reference case and three variations of the split blade with full, partial and missing sealing in the gap between the segments, were assessed using five-hole probe measurements. By investigating a wide range of stagger angles, the coverage of the full low-loss working range of the VIGV could be ensured. Especially, the fully sealed split blade configuration proved its capacity to extend the efficient operational range significantly.
Published: 13 September 2021
Journal of Turbomachinery pp 1-21; https://doi.org/10.1115/1.4052402

Abstract:
Scale-resolving simulations, such as large eddy simulations, have become affordable tools to investigate the flow in turbomachinery components. The resulting time-resolved flow field is typically analyzed using first- and second-order statistical moments. However, two sources of uncertainty are present when recording statistical moments from scale-resolving simulations: the influence of initial transients and statistical errors due to the finite number of samples. In this paper, both are systematically analyzed for several quantities of engineering interest using time series from a long-time large eddy simulation of the low-pressure turbine cascade T106C. A set of statistical tools to either remove or quantify these sources of uncertainty is assessed. First, the Marginal Standard Error Rule is used to detect the end of the initial transient. The method is validated for integral and local quantities and guidelines on how to handle spatially varying initial transients are formulated. With the initial transient reliably removed, the statistical error is estimated based on standard error relations considering correlations in the time series. The resulting confidence intervals are carefully verified for quantities of engineering interest utilizing cumulative and simple moving averages. Furthermore, the influence of periodic content from large scale vortex shedding on the error estimation is studied. Based on the confidence intervals, the required averaging interval to reduce the statistical uncertainty to a specific level is indicated for each considered quantity.
, Michal Majchrzyk, Katarzyna Kolodziej
Journal of Energy Resources Technology pp 1-13; https://doi.org/10.1115/1.4052413

Abstract:
The paper presents the possibility of energy storage in natural gas transmission networks using 2 strategies. Proof-of-concept calculations were performed under a steady-state assumption, and the more promising option was additionally modeled in a transient approach. The first strategy is based on a dedicated compressor–expander system installed at two ends of a pipeline. An electric driven compressor increases the gas pressure in periods of peak electricity generation, while a gas expander allows energy recovery at a later stage. The compressor expander distance determined by the inlet flow velocity of 5 m/s and a 4–5 h time shift ranges from approx. 75 to 120 km. The system provides a synergy effect, which allows to exceed 100% storage efficiency by reducing transmission losses. Storage efficiency obtained from the simplified model ranges from 70 to 128% for the performed case study. The second option uses existing compressors and pressure let down stations expanding the gas to the distribution pressure. Here, gas pre-heating required prior to the expansion reduces the storage efficiency to about 30-40%. The dedicated machinery option was also evaluated using a transient model, which reports a lower efficiency if applied to the same assumptions. The system redesigned with the transient model is characterized by a longer storage duration (about 12 h) and a promising efficiency of 103.5%. Further research is needed to find the optimum design system parameters and to solve the detected problem of simultaneous compressor-expander operation which introduces idle work to the designed system.
Journal of Manufacturing Science and Engineering pp 1-8; https://doi.org/10.1115/1.4052388

Abstract:
Thermal deviation induced by ambient temperature changes and heat generated during machine operations influences the accuracy of machine tools. A thermal test is essential to evaluate the influence of thermal deviation. ISO 230-3 provides displacement sensor-based thermal tests for machine tools. This paper proposes a machining test that enables a user to visually, by the naked eye, observe the integrated thermal influence on the tool trajectory's displacement in the direction normal to the test piece surface from the length of the machined slots. The proposed test consists of the machining of the five surfaces to observe the thermal influence of the tool position with respect to the test piece in X-, Y- and Z-directions, as well as the position of two rotary axes with respect to the tool position. The advantages of the proposed test include that it requires no measuring instrument to quantitatively evaluate the thermal error in all directions. And since the thermal influence is evaluated by observing the position where the cutting tool leaves the test piece surface, where the cutting force is zero, the influence of the cutting force on the test results can be ignored. Thermal influences of a five-axis machine tool during the warm-up cycle are investigated by experiment to validate the feasibility of the proposed method. Results show that 150 min is needed for sufficient warm-up for the selected machine tool if permissible tolerance for thermal deviation is 2.5 um for all the errors.
Yuhan Ji, Weihai Chen, , Zhongyi Li, , Guilin Yang
Journal of Mechanisms and Robotics pp 1-25; https://doi.org/10.1115/1.4052380

Abstract:
The upper limb rehabilitation exoskeleton with cable-driven parallel structure has the advantages of light weight and large payload, etc. However, due to the non-rigid nature of the actuating cables and the different body shape of the wearer, the geometric parameters of the exoskeleton have a large error. The parameter identification of cable-driven exoskeleton is of great significance. An asynchronous self-identification method for the upper limb 7-DOF (Degree of freedom) cable-driven exoskeleton was proposed and used in a wearable multi-redundant exoskeleton. Asynchronous iteration eliminates the accumulation of joint errors. High identification reliability is achieved by selecting proper identification parameters and optimizing error model.With the method, the geometric parameters of the exoskeleton can be identified by using exoskeleton joint Angle and cable length data. The experiment verifies that the success rate of parameter identification for different wearers is in line with expectations, and the control precision and stability of the prototype are greatly improved after parameter identification.
Shuo Wang, , Xiwang He, Yiming Qiu, Xueguan Song
Published: 13 September 2021
Journal of Mechanical Design pp 1-28; https://doi.org/10.1115/1.4052390

Abstract:
Digital twin has the potential for increasing production, achieving real-time monitor, and realizing predictive maintenance by establishing a real-time high-fidelity mapping between the physical entity and its digital model. However, the high accuracy and instantaneousness requirements of digital twins have hindered their applications in practical engineering. This paper presents a universal framework to fulfill the requirements and to build an accurate and trustworthy digital twin by integrating numerical simulations, sensor data, multi-fidelity surrogate (MFS) models, and visualization techniques. In practical engineering, the number of sensors available to measure quantities of interest is often limited, complementary simulations are necessary to compute these quantities. The simulation results are generally more comprehensive but not as accurate as the sensor data. Therefore, the proposed framework combines the benefits of both simulation results and sensor data by using an MFS model based on moving least squares, named MFS-MLS. The MFS-MLS was developed as an essential part to calibrate the continuous field of the simulation by limited sensor data to obtain accurate results for the digital twin. Then single-fidelity surrogate models are built on the whole domain using the calibrated results of the MFS-MLS as training samples and sensor data as inputs to predict and visualize the quantities of interest in real-time. In addition, the framework was validated by a truss test case, and the results demonstrate that the proposed framework has the potential to be an effective tool to build accurate and trustworthy digital twins.
, , Harrison Kim
Published: 13 September 2021
Journal of Mechanical Design pp 1-11; https://doi.org/10.1115/1.4052389

Abstract:
Remanufacturing is a representative product recovery strategy that can improve economic profitability and sustainability by restoring discarded or traded-in used products to a like-new condition. Unlike the production process of new products, remanufacturing requires unique production processes, such as collecting used products and dis(re)assembly. Therefore, several factors need to be considered for the design of remanufactured products. First, when designing a remanufactured product, it is crucial to ensure that the specifications of components meet the customer's requirements because the remanufacturing uses relatively outdated components or modules. In addition, it is necessary to consider the disassembly level and order to facilitate the disassembly process to obtain the desired parts. This study proposes an integrated model to (i) find configuration design suitable for remanufactured products that can maximize customer utility based on End-of-life products, and (ii) establish a harvest plan that determines the optimal disassembly operations and levels. This proposed model can be used as a decisionmaking tool that helps product designers find the appropriate design of remanufactured products while increasing the efficiency of the remanufacturing process.
Published: 13 September 2021
Journal of Mechanical Design pp 1-53; https://doi.org/10.1115/1.4052391

Abstract:
Decomposition is a dominant design strategy because it enables complex problems to be broken up into loosely-coupled modules that are easier to manage and can be designed in parallel. However, contrary to widely held expectations, we show that complexity can increase substantially when natural system modules are fully decoupled from one another to support parallel design. Drawing on detailed empirical evidence from a NASA space robotics field experiment we explain how new information is introduced into the design space through three complexity addition mechanisms of the decomposition process: interface creation, functional allocation, and second order effects. These findings have important implications for how modules are selected early in the design process and how future decomposition approaches should be developed. Although it is well known that complex systems are rarely fully decomposable and that the decoupling process necessitates additional design work, the literature is predominantly focused on reordering, clustering, and/or grouping based approaches to define module boundaries within a fixed system representation. Consequently, these approaches are unable to account for the (often significant) new information that is added to the design space through the decomposition process. We contend that the observed mechanisms of complexity growth need to be better accounted for during the module selection process in order to avoid unexpected downstream costs. With this work we lay a foundation for valuing these complexity-induced impacts to performance, schedule and cost, earlier in the decomposition process.
Zekai Wang, Feng Gao, Chengzheng Cai, ,
Journal of Energy Resources Technology pp 1-12; https://doi.org/10.1115/1.4052414

Abstract:
The thermal stress caused by the ultra-low temperature of liquid nitrogen (LN2) can seriously affect the porosity of the coalbed. In this paper, the effects of various temperature differences on the LN2 damage were studied by changing the initial temperature, so as to explore the effect of LN2 on coal seam with different buried depth. The x-ray diffraction (XRD), scanning electron microscope (SEM), wave velocity, acoustic emission (AE) and uniaxial compression experiments were used in the experiments. The experimental results show that LN2 does do a lot of damage to coal and the LN2 effect increase at first and then decrease with the increase of the initial temperature. When the initial temperature is 293K, before and after liquid nitrogen treatment, the wave velocity damage of the coal sample reaches 0.2207 and the compressive strength decreases by 27.92%. These two values are 0.3697 and 47.37% at the initial temperature of 323K, and 0.2727 and 28.27% at the initial temperature of 353K.. This is because if the temperature exceeds 353 K, it will cause a 3.17% drop in water content, thus reducing the damage caused by LN2, resulting in the overall effect slightly lower than that at 323 K.
Published: 13 September 2021
Journal of Turbomachinery pp 1-14; https://doi.org/10.1115/1.4052405

Abstract:
This paper expands upon a multi-degree-of-freedom, Van der Pol oscillator used to model buffet and Nonsynchronous Vibrations (NSV) in turbines. Two degrees-of-freedom are used, a fluid tracking variable incorporating a Van der Pol oscillator and a classic spring, mass, damper mounted cylinder variable; thus, this model is one of fluid-structure interaction. This model has been previously shown to exhibit the two main aspects of NSV. The first is the lock-in or entrainment phenomenon of the fluid shedding frequency jumping onto the natural frequency of the oscillator, while the second is a stable limit cycle oscillation (LCO) once the transient solution disappears. Improvements are made to the previous model to better understand this aeroelastic phenomenon. First, an error minimizing technique through a system identification method is used to tune the coefficients in the Reduced Order Model (ROM) to improve the accuracy in comparison to experimental data. Secondly, a cubic stiffness term is added to the fluid equation; this term is often seen in the Duffing Oscillator equation, which allows this ROM to capture the experimental behavior more accurately, seen in previous literature. The finalized model captures the experimental cylinder data found in literature much better than the previous model. These improvements also open the door for future models, such as that of a pitching airfoil or a turbomachinery blade, to create a preliminary design tool for studying NSV in turbomachinery.
Journal of Thermal Science and Engineering Applications pp 1-16; https://doi.org/10.1115/1.4052378

Abstract:
With the rising demand of clean and energy efficient air conditioning systems, evaporative air cooling technique is gaining significant attention owing to less energy consumption and environmentally safe technology in comparison with conventional refrigerants based air conditioners. In this study, commercial desiccant dehumidifier is coupled with experimentally developed Direct Evaporative Cooling (DEC) system in order to first dehumidify the air, and then pass it through DEC to achieve human thermal comfort level defined by ASHRAE standards. Under the climatic conditions of Islamabad-Pakistan, multiple experiments were carried out at different temperatures, flow rate and relative humidity of air during November, when air temperature and relative humidity was in the range of 25-30°C and 40%-60%, respectively. In order to analyze the system performance under summer ambient conditions, indoor temperature was increased by 8-10°C and relative humidity by 15%-25% in laboratory. Experimental analysis showed that the system can provide human comfort level for a range of temperature 29-39.7°C and relative humidity of 65-80% at flow rate of 180 m3/hr. In order to achieve thermal comfort at higher humidity level, DEC is coupled with commercial desiccant dehumidifier. However, due to desiccant regeneration by an electric heater in the dehumidifier, the overall power consumption of the whole system rises up to 1.95 kW. Two well-known indices Coefficient of Performance (CoP) and Energy Efficiency Ratio (EER) are used to analyze the system performance.
Abdulazeez Abdulraheem
Journal of Energy Resources Technology pp 1-13; https://doi.org/10.1115/1.4052412

Abstract:
The acoustic data in terms of compressional and shear wave velocity provide important petrophysical information about the rock. The sonic data is a significant input that is commonly used for deriving geomechanical parameters. Understanding the geomechanical properties of reservoir rock is essential during the drilling, development, production, and stimulation of an oil or gas reservoir. Among them, Young's modulus and Poisson's ratio are the most important elastic parameters. These properties are usually estimated from bulk density, compressional and shear wave velocity log data. Sonic data acquisition is usually achieved through dipole sonic imager log or laboratory testing on core samples which is costly and time-consuming. Acquiring sonic data from wireline logs is not feasible approach all the time; as the wireline log, specially shear-wave log, may not be recorded for every well. However, drilling data is available in a real-time for every well using real-time drilling sensors. The main objective of this paper is to predict sonic slowness logs in real-time based on the drilling data using artificial neural network (ANN). The data used in this study were recorded during the drilling of 12 ¼” hole sections from two wells. Many formations of different lithology were penetrated while drilling these sections of over 3000 ft vertical interval. The drilling and sonic datasets were recorded and preprocessed before using them for the ANN model. 2900 data points from the first well were used for building and testing the model. The input parameters included weight on bit (WOB), torque (T), standpipe pressure (SPP), pipe speed (PS), rate of penetration (ROP), and mud flow rate (Q). Another dataset of 2000 data points from the second well that was drilled in the same field was used to validate the model. The predictions were compared with sonic logs that were obtained after the drilling operation and the results appear to be highly promising for future applications. The sonic slowness ANN models showed a high accuracy for the model building (training and testing). Validation of these models was carried out using an unseen dataset. The results using the validation dataset for the compressional slowness model yielded a coefficient of determination (R2) of 0.983 and average absolute percentage error (AAPE) of less than 1.25%. For the shear slowness model, R2 was higher than 0.994 and AAPE less than 1.175%. The study offers empirical correlations that can be utilized to estimate the sonic slowness logs by engineers without the need to employ ANN software. The new shear slowness correlation was compared with other widely used correlations and the results showed high accuracy.
, Zhen-Yu Zhou, Zhong-Yu Piao, Zhanpeng Mao
Journal of Manufacturing Science and Engineering pp 1-22; https://doi.org/10.1115/1.4052392

Abstract:
With the urgent demand of high-end equipment for high quality surfaces, the technique of ultrasonic vibration-assisted burnishing is introduced to strengthen the surface properties. To explore the influence of the ultrasonic vibration on the dynamic response of a burnishing system, the burnishing friction force generated from a multi-ball surface burnishing system was characterized by chaos theory. The system had four assisted forms: no ultrasonic vibration, one-dimensional (1D) ultrasonic in x-axis, 1D ultrasonic in z-axis, and 2D ultrasonic in xz-axis. The results showed that any burnishing system had chaotic nature. Under the 2D ultrasonic vibration-assisted burnishing, the burnishing friction force was reconstructed to be a chaotic attractor with high convergence degree. Moreover, the burnishing system has notable complexity and stability. The burnished Al7075 alloy sample has an excellent surface with a higher smoothness and hardness. The burnishing with 2D ultrasonic vibration in xz-axis is a technique to enhance surface properties.
Published: 13 September 2021
Journal of Applied Mechanics pp 1-15; https://doi.org/10.1115/1.4052375

Abstract:
Viscoelastic material behavior in polymer systems largely arises from dynamic topological rearrangement at the network level. In this paper, we present a physically motivated microsphere formulation for modeling the mechanics of transient polymer networks. By following the directional statistics of chain alignment and local chain stretch, the Transient Microsphere Model (TMM) is fully anisotropic and micro-mechanically based. Network evolution is tracked throughout deformation using a Fokker-Planck equation which incorporates the effects of bond creation and deletion at rates that are sensitive to the chain-level environment. Using published data, we demonstrate the model to capture various material responses observed in physical polymers.
Journal of Energy Resources Technology pp 1-22; https://doi.org/10.1115/1.4052415

Abstract:
Today, enhance oil recovery (EOR) methods are attracting more attention to increase the petroleum production rate. Some EOR methods such as low salinity water flooding (LSW) can increase the amount of fine migration and sand production in sandstone reservoirs which causes a reduction in permeability and inflict damages on to the reservoir and the production equipment. One of the methods to control fine migration is using nanotechnology. Nanoparticles (NPs) can reduce fine migration by various mechanisms such as reducing the zeta potential of fine particles' surfaces. In this paper, three NPs including SiO2, MgO, and Al2O3 's effects on controlling fine migration and sand production were investigated in two scenarios of pre-flush and co-injection by using sandpack as a porous media sample. When NPs are injected into the porous media sample, the outflow turbidity and zeta potential of particles decreases. Experiments showed that SiO2 has the best effect on controlling fine migration in comparison with other NPs and it could reduce fine migration 69% in pre-flush and 75% in co-injection. Also, MgO and Al2O3 decreased fine migration 65% and 33% in the pre-flush scenario and 49%,13% in the co-injection scenario, respectively.
Nannan Chen, , Jingjing Li, ,
Journal of Manufacturing Science and Engineering pp 1-12; https://doi.org/10.1115/1.4052387

Abstract:
Dissimilar materials of copper (Cu) to aluminum (Al) with nickel-phosphorus (Ni-P) coatings were joined using resistance spot welding. The Ni-P coatings were electroless plated on the Al surfaces to eliminate the formation of brittle Cu-Al intermetallic compounds (IMCs) at the faying interface of Cu to Al. Three welding schedules with various heat input were employed to produce different interfacial microstructure. The evolution of interfaces in terms of phase constitution, elemental distribution and defects (gaps and voids) was characterized and the formation mechanisms were elucidated. During the welding, the bonding between Cu and Ni-P form through solid-state diffusion, while the faster diffusion rate of Cu relative to Ni and P atoms promotes the generation of sub-micro voids. As the heat input increases, gaps at the Cu/Ni-P interface diminishes accompanied by increase of sub-micro voids. A moderate schedule helps to remove the gaps and inhibit the voids formation. An Al3Ni layer and nanovoids were found around the interface of Ni-P/Al. The increased heat input decreases the grain size of Al3Ni at the interface by eutectic remelting and increases the nanovoids by enhanced nanoscale Kirkendall effect.
Journal of Manufacturing Science and Engineering pp 1-26; https://doi.org/10.1115/1.4052386

Abstract:
A super-layer deposition method is developed for 3D macroscopic finite element modeling of heat transfer at part scale during the powder bed fusion (PBF) process. The proposed super-layer strategy consists of the deposition of batches of several layers. The main consideration is to deal with the effective heating times and with the inter-layer dwell time in a reasonable way. The material is deposited at once for each super-layer thanks to level-set and mesh adaptation methods, while the energy input is prescribed, either by respecting the layer-by-layer thermal cycle, or in a single thermal load. The level set method is used twice: first to track the interface between gas and the successive super-layers of powder bed and; second to track the interface between the part in construction and the non-exposed powder. To preserve simulation accuracy, adaptive remeshing is used to maintain a fine mesh near the evolving construction front during the process. Simulation results obtained by means of this super-layer method are presented and discussed by comparison with those obtained by layer-by-layer strategy, considered here as a reference. It is shown that, when respecting certain conditions, temperature evolutions and distributions approaching the reference ones can be obtained with significant savings on computation time. Assessment is first performed on simple part, then on a more complex configuration.
Journal of Energy Resources Technology pp 1-13; https://doi.org/10.1115/1.4052410

Abstract:
Volume and salt concentrations in Marcellus flowback water depend on geology, drilling and completions, stimulation and flowback operations. Recent studies include evaluations of geochemical origins based on the compostition concentrations, flowback sampling analysis and numerical studies. However, an in-depth understanding of chemical compositions as well as the changes of compositions is still needed. In this paper, we will first review the literature related to flowback water in Marcellus shale gas wells to fully understand the chemistry, geochemistry, and physics governing a fracture treatment, shut-in, and flowback. We will then gather all public and in-house flowback data, named as 3-week or 3-month flowback in this work, to build a data set of flowback water compositions. After data screening, we will then analyze this database using four different methods: geographical changes over time, linear regression, clustering and multi-variable analysis. New understandings such as the magnitude and prevailing trends of concentrations for target constituents as well as the correlations among flowback compositions, the differentiation between early and late time flowback water were obtained and explained on the basis of geochemistry and physics. This helps production companies and other stakeholders to better manage and reuse waste water for energy production.
, Xu Zhang, Di Peng, Yingzheng Liu, Wenwu Zhou, Wen-Bin Chen, , Fei Zeng
Published: 13 September 2021
Journal of Turbomachinery pp 1-24; https://doi.org/10.1115/1.4052406

Abstract:
The viewing angle for optical aerothermal measurements on turbine surfaces is often limited by the turbine structure, requiring the optical system to have a large depth of field (DoF). Although the DoF can be increased by decreasing the lens aperture, this approach is impractical as a large aperture is essential to maintain an acceptable signal-to-noise ratio (SNR). To solve these problems in the optical aerothermal measurements of film-cooled gas turbine blades, an approach combining the focal sweep method and three-dimensional (3D) reconstruction is proposed. The focal sweep method is used to obtain all-in-focus images at an inclined viewing angle, following which the two-dimensional image is restored through 3D reconstruction. Thus, 3D point clouds with both a large DoF and high SNR can be produced. The developed method was validated via flat-plate film cooling experiments using pressure-sensitive paint at three blowing ratios of 0.4, 0.8, and 1.2, as well as three viewing angles. The measured adiabatic effectiveness contours demonstrate that the proposed method can produce all-in-focus measurements at highly inclined viewing angles, albeit at the price of 6% maximum difference compared to the normal view. Furthermore, the proposed method was applied to the turbine blade film cooling experiment at a highly inclined viewing angle, and successfully reconstructed the 3D effectiveness point cloud at the curved turbine blade surface.
Bangxiang Chen, , , , Weiliang Xu
Journal of Mechanisms and Robotics pp 1-28; https://doi.org/10.1115/1.4052379

Abstract:
Assessing the food texture via mastication is important for advancing knowledge of food properties so as to develop favorable and healthy food products. Oral processing of food by robots can enable an in vitro assessment of food texture by simulating human mastication objectively. In this study, a chewing robot is developed to mimic the rhythmic motion of the molars to enable controllable chewing kinematics and a biomimetic oral environment. The robotic chewing is realized using a 3 degree-of-freedom (DOF) linkage mechanism, which recreates the molar grinding movement based on molar trajectories and chewing cycle durations previously reported in the literature. Moreover, a soft pneumatically actuated cavity is developed to provide a space to contain and reposition the food between occlusions. In order to regulate the robotic chewing having variable molar trajectories and chewing durations, the mathematical relationship of the linkage's actuators and molar movements is investigated for the purpose of motion analysis and control. Accordingly, the design of the robot in terms of linkage, oral cavity and mechatronics system is performed. The built robot is validated by tracing a planned variable molar trajectory while chewing peanuts. The performance of robot chewing is validated by demonstrating the ability of the robot to chew the peanuts similar to that by human through comparison of peanut particle size distributions (PSDs) and particle median size diameters.
Nandana Menon, , Amrita Basak
Published: 13 September 2021
Journal of Turbomachinery pp 1-19; https://doi.org/10.1115/1.4052404

Abstract:
Nickel-base superalloys are extensively used in the production of gas turbine hot-section components as they offer exceptional creep strength and superior fatigue resistance at high temperatures. Such improved properties are due to the presence of precipitate-strengthening phases such as Ni3Ti or Ni3Al (gγ phases) in the normally face-centered cubic (FCC) structure of the solidified nickel. Although this second phase is the main reason for the improvements in properties, the presence of such phases also results in increased processing difficulties as these alloys are prone to crack formation. In this work, specimens of IN738LC are fabricated on a Coherent Creator laser powder bed fusion (L-PBF) additive manufacturing (AM) equipment. Optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-Ray diffraction (XRD) are carried out to characterize the deposit region. Metallurgical continuity is achieved in the entire deposit region and the specimens do not show any warpage. However, the specimens show voids (e.g., pores and cracks) in the deposit region. The results show that the percentage void area decreases along the build height direction. The deposited IN738LC shows polycrystalline grains in the entire deposit region as confirmed by XRD and EBSD. The grain size also shows variations along the build direction. In summary, the results open opportunities for academic researchers and small scale businesses in fabricating high-gγ nickel-base superalloys on a desktop laser powder bed fusion AM equipment
Journal of Energy Resources Technology pp 1-16; https://doi.org/10.1115/1.4052411

Abstract:
The present investigation attempts to explore the prospects of the engine operational stability of a methanol induced partially premixed dual fuel operation under split injection strategy operating on a conventional single cylinder diesel engine coupled with a dedicated CRDI. The operation of such LTC regimes often deals with the stability concerns which are primarily characterized as the harshness of the operations and the non-repeatability of the combustion cycles. These two markers of operational stability have been mapped in this study through a comprehensive set of metrics of maximum pressure rise rate (ROPRmax) and Coefficient of Variation of Indicated Mean Effective Pressure (COVIMEP), Peak Pressure (COVPP) and Crank Angle of 50% mass fraction burn (COVCA50). The parametric investigation has been carried out at three different injection timings and pilot mass percentages at predefined methanol injection durations. The results have shown tremendous reductions in the non-repeatability of the combustion cycles and the harshness of the engine operation under split injection strategy, indicated by the lower scores of the stability indicators in comparison to the baseline single injection operation. Subsequently, the lowest scores of the maximum pressure rise rate and the Coefficient of Variation of indicated mean effective pressure, peak pressure and CA50 for the entire scope of investigation were registered as 0.62bar/CA, 0.75%, 0.48% and 1%, which were apparently observed as 65.5%, 86.36%, 94% and 53% lower than the corresponding scores registered in the baseline single injection operation.
Published: 13 September 2021
Journal of Turbomachinery pp 1-33; https://doi.org/10.1115/1.4052407

Abstract:
Modern gas turbines lean combustors are used to limit NOx pollutant emissions; on the other hand, their adoption presents other challenges, especially concerning the combustor-turbine interaction. Turbine inlet conditions are generally characterized by severe temperature distortions and swirl degree, which is responsible for very high turbulence intensities. Past studies have focused on the description of the effects of these phenomena on the behavior of the high pressure turbine. Nevertheless, very limited experimental results are available when it comes to evaluate the heat transfer coefficient (HTC) on the nozzle guide vane surface, since relevant temperature distortions present a severe challenge for the commonly adopted measurement techniques. The work presented in this paper was carried out on a non-reactive, annular, three-sector rig, made by a combustor simulator and a NGV cascade. It can reproduce a swirling flow, with temperature distortions at the combustor-turbine interface plane. This test apparatus was exploited to develop an experimental approach to retrieve heat transfer coefficient and adiabatic wall temperature distributions simultaneously, to overcome the known limitations imposed by temperature gradients on state-of-the-art methods for HTC calculation from transient tests. A non-cooled mockup of a NGV doublet, manufactured using low thermal diffusivity plastic material, was used for the tests, carried out using IR thermography with a transient approach. In the authors' knowledge, this presents the first experimental attempt of measuring a nozzle guide vane heat transfer coefficient in the presence of relevant temperature distortions and swirl.
, , Bikramjit Basu
Journal of Biomechanical Engineering; https://doi.org/10.1115/1.4052373

Abstract:
The wear of acetabular liner is one of the key factors determining the longevity and osseointegration of Total Hip Replacement (THR) implants. The long-term experimental measurements of wear in THR components are time and cost-intensive. A finite element (FE) model of a 32 mm Ceramic on Polymer system consisting of ZTA (Zirconia-toughened Alumina) femoral head and UHMWPE (Ultrahigh molecular weight polyethylene) liner was developed to predict the dynamic wear response of the liner. Archard-Lancaster equation, consisting of surface contact pressure, wear rate, and sliding distance, was employed to predict the wear in the liner. The contact pressure and wear at the articulating surface were found to decrease over time. A new computational method involving 3D point clouds from the FE analyzed results were used to construct wear maps. The model was able to predict the linear wear with relative errors ranging from 9% to 36% over 2 million cycles when compared to the published results. The increasing error percentage occurring primarily from the use of a constant wear rate was reduced to a maximum of 17% by introducing a correction factor. Volumetric wear rate was predicted with a maximum relative error of 7% with the implementation of the correction factor. When the model was implemented to study liners of diameters ranging from 28 mm to 36 mm, the linear wear was seen to decrease with an increase in femoral head diameter, which is in agreement with the clinical data.
Journal of Pressure Vessel Technology; https://doi.org/10.1115/1.4052397

Abstract:
Creep deformation behavior, creep strength property and microstructural evolution during creep exposure were investigated on Super 304H steel for boiler tube. In the high stress and lower temperature regime, creep rupture strength of Super 304H steel is higher than that of SUS304H steel. The slope of stress vs. time to rupture curve of Super 304H steel, however, becomes steeper with increase in creep exposure time and temperature, and the creep rupture strength of Super 304H steel becomes closer to that of SUS304H steel after the tens of thousands of hours at 700°C and above. In the short-term, at 600°C, creep rupture ductility increases with increase in creep rupture life. However, it tends to decrease after showing the maximum value and the creep rupture ductility decreases with increase in temperature. The complex shape of creep rate vs. time curves, with two minima in creep rate, was observed at 600°C. Several type precipitates of niobium carbonitride (Nb(C,N)), Z phase (NbCrN), and copper were observed in Super 304H steel, as well as M23C6 carbide and sigma phase observed in SUS304H steel. The change in slope of stress vs. time to rupture curve is caused by disappearance of precipitation strengthening effect during creep exposure. Accuracy of creep rupture life evaluation was improved by stress range splitting method which takes into accounts of the change in slope of stress vs. time to rupture curves was demonstrated.
, Hyunguk Kwon, Drue Seksinsky, Daniel G Doleiden, Jacqueline O'Connor, Yuan Xuan, ,
Journal of Engineering for Gas Turbines and Power; https://doi.org/10.1115/1.4052384

Abstract:
Pilot flames are commonly used to extend combustor operability limits and suppress combustion oscillations in low-emissions gas turbines. Combustion oscillations, a coupling between heat release rate oscillations and combustor acoustics, can arise at the operability limits of low-emissions combustors where the flame is more susceptible to perturbations. In this study, we consider the impact of a central jet pilot on the stability of a swirl-stabilized flame in a variable-length, single-nozzle combustor. Previously, the pilot flame was found to suppress the instability for a range of equivalence ratios and combustor lengths. We hypothesize that combustion oscillation suppression by the pilot occurs because the pilot provides hot gases to the vortex breakdown region of the flow that recirculate and improve the static, and hence dynamic, stability of the main flame. This hypothesis is based on a series of experimental results that show that pilot efficacy is a strong function of pilot equivalence ratio but not pilot flow rate, which would indicate that the temperature of the pilot gases as well as the combustion intensity of the pilot flame play more of a role in oscillation stabilization than the length of the pilot flame relative to the main flame. To understand these results, we use large-eddy simulation to provide a detailed analysis of the flow in the region of the pilot flame and the transport of radical species in the region between the main flame and pilot flame.
Journal of Pressure Vessel Technology; https://doi.org/10.1115/1.4052399

Abstract:
Fluidelastic instability (FEI) is well known to be a critical flow-induced vibration concern for the integrity of the tubes in nuclear steam generators. Traditionally, this has been assumed to occur in the direction transverse to the direction of flow but the tube failures at San Onofre Nuclear Generating Station (SONGS) in Los Angeles proved that this assumption is not generally valid. A simple tube-in-channel theoretical model was previously developed to predict streamwise as well as transverse FEI in a parallel triangular tube array. This predicted that this array geometry was particularly sensitive to streamwise FEI for high mass-damping parameters and small pitch ratios, the conditions in which the SONGS failures occurred. The advantage of this simple modelling approach is that no new empirical data are required for parametric studies of the effects of tube pattern and pitch ratio on FEI. The tube-in-channel model has been extended to in-line square, normal triangular and rotated square tube arrays and the stability of these geometric patterns are analyzed for the effects of varying pitch ratio and the mass-damping parameter. The results are compared with the available experimental data and conclusions are drawn regarding the relative vulnerability of these different tube array geometries to streamwise FEI.
Victor Coppo Leite, Elia Merzari
Published: 10 September 2021
Journal of Fluids Engineering; https://doi.org/10.1115/1.4052416

Abstract:
In the present study, we examine in detail the effect of spatially dependent viscosity on wall-bounded flow. For this purpose, Direct Numerical Simulations (DNS) are performed considering a channel flow with a viscosity change along the streamwise direction. The DNS were performed using Nek5000, a computational fluid dynamic code developed at Argonne National Laboratory. The channel is divided in three different regions: in the first one, the flow is at a constant Reynolds number of Re = 5000; in the second region, the Reynolds number is imposed to linearly increase as viscosity decreases through a ramp; finally, in the third region the flow is again at a constant Reynolds number, this time at Re = 10000. Since the temperature field is not evaluated, the proposed set up is a simplification of a heated channel. Nevertheless, the outcomes of this study may be valuable for future works considering variable-viscosity effects, especially for cooling and heating applications. Four test cases with different ramp inclinations were analyzed. The results from the present study were compared with a correlation available in the literature for the friction Reynolds number as a function of the Reynolds number. We observe that in all cases the ramp does not cause an immediate change in the characteristics of turbulent structures and a delay is in fact observed in both wall shear and friction. Finally, in order to characterize and understand these effects, streaks from the viscous region and turbulence statistics for the turbulent kinetic energy budget terms are analyzed.
Ji-Hoon Kang, ,
Journal of Pressure Vessel Technology; https://doi.org/10.1115/1.4052398

Abstract:
Accurate estimation of elastic-plastic fracture mechanics (EPFM) parameters for a crack in nuclear pipes was considered as an important factor for leak-before-break (LBB) design and evaluation. Yet few EPFM studies have been made to predict the crack opening displacement (COD) and J-integral of dissimilar metal welded pipes, which consist of two-layered materials (TLMs), due to the difficulty of complicate analysis encompassing both through-wall crack and internal surface crack in radial and circumferential directions. In this study, a series of finite element (FE) analyses to determine the typical EPFM parameters were carried out considering idealized complex-cracked pipes with TLMs. The analyses were elaborated through applying three loading conditions of axial tension, bending moment and internal pressure. Both J-integral and COD values were calculated by assuming two kinds of equivalent materials based on weighted average concepts as well as two different materials. The proposed equivalent schemes can be utilized in not only improvement to existing solutions but also more accurate detailed LBB assessment of complex cracked nuclear piping with TLMs.
Journal of Biomechanical Engineering; https://doi.org/10.1115/1.4052374

Abstract:
Acoustic droplet vaporization (ADV) has proven to enhance high intensity focused ultrasound (HIFU) thermal ablation of tumor. It has also been demonstrated that triggering droplets before HIFU exposure could be a potential way to control both the size and the shape of the thermal lesion. In this paper, a numerical model is proposed to predict the thermal lesion created in ADV enhanced HIFU treatment. Bubble oscillation was coupled into a viscoelastic medium in the model to more closely represent real applications in tissues. Several physical processes caused by continuous wave ultrasound and elevated temperature during the HIFU exposure were considered, including rectified diffusion, gas solubility variation with temperature in the medium, boiling, etc. Four droplet concentrations spanning two orders of magnitude were calculated. The bubble cloud formed from triggering of the droplets by the pulse wave ultrasound, along with the evolution of the shape and location of the bubble cloud and thermal lesion during the following continuous wave exposure were obtained. The increase of bubble void fraction caused by continuous wave exposure were found to be consistent with the experimental observation. With the increase of droplet concentration, the predicted bubble cloud shapes vary from tadpole to triangular and double triangular, while the thermal lesions move toward the transducer. The results show that the assumptions used in this model increased the accuracy of the results. This model may be used for parametrical study of ADV enhanced HIFU treatment and be further used for treatment planning and optimization in the future.
Journal of Nuclear Engineering and Radiation Science; https://doi.org/10.1115/1.4052376

Abstract:
The Eddy Current Flowmeter (ECFM) sensor plays an important part in the instrumentation of the future Sodium Fast Reactors (SFR), which will allows when located above the core to detect plugging (partial or total) of a sub assembly and when located on the primary pump to measure core pressure drop and core flowrate. This document describes the pre-design phase of a mock-up for ECFM tests and qualifications under sodium conditions for the detection of a partial or full plugging of a fuel sub-assembly. These tests will be the first of their kind, as the ECFM had never been qualified at nominal conditions of a reactor core outlet (sodium temperature, velocity and output flow).
Published: 10 September 2021
Journal of Heat Transfer, Volume 143; https://doi.org/10.1115/1.4051764

Abstract:
This paper considers the three-phase lag (TPL) bioheat model to study the phase change phenomena in skin tissue during cryosurgery. The considered TPL model is based on the model of thermo-elasticity, i.e., the combination of the rate of thermal conductivity and new phase lag (τv) due to thermal displacement. An effective heat capacity-based numerical algorithm is established to solve the nonlinear governing equation for biological tissue freezing. Space and time derivatives appearing in the mathematical model are approximated using the radial basis function (RBF) and finite difference method (FDM), respectively. The impact of three nonclassical models, single-phase lag (SPL), dual-phase lag (DPL), and TPL, on the freezing process is studied. The effects of phase lags involved in the models on freezing are also part of this study.
Connor Huxman,
Published: 10 September 2021
Journal of Medical Devices, Volume 15; https://doi.org/10.1115/1.4052011

Abstract:
Currently available motion-preserving orthopedic implants offer many advantages but have several limitations to their use, including short device lifetime, high part count, loss of natural kinematics, and wear-induced osteolysis and implant loosening. Compliant mechanisms have been used to address some of these problems as they offer several potential advantages - namely, wear reduction, reduced part count, and the ability to achieve complex, patient-specific motion profiles. This article provides a systematic review of compliant mechanisms as orthopedic implants. Based on the PRISMA guidelines for an efficient review, this work identified fourteen implantable orthopedic devices that seek to restore anatomical motion by utilizing mechanical compliance. From reviewing these implants and their results, advantages and consequences for each are summarized. Trends were also identified in how these devices are capable of mitigating common challenges found in orthopedic design. Design considerations for the development of future compliant orthopedic implants are proposed and discussed.
Published: 10 September 2021
Journal of Medical Devices, Volume 15; https://doi.org/10.1115/1.4052012

Abstract:
Fatigue is a major challenge encountered in cardiovascular implant design. While the properly heat-treated Nitinol can exhibit up to 6–7% recoverable strains allowing for minimally invasive transcatheter delivery of cardiovascular implants, the cyclic in vivo loading can cause premature fracture of the implant if the fatigue strain is too high. Strain-based criteria have been adopted for the development of Nitinol fatigue resistance. Lacking experimental tools to characterize the local material fatigue strain, fatigue testing of Nitinol specimens has largely relied on the finite element analysis to compute the cyclic strain amplitude and mean strain based on experimentally derived constitutive parameters using phenomenological strain energy theory. Without a consistent computational standard, previous works have resulted in controversy and inconsistency in the impact of mean strain on the fatigue resistance of Nitinol in terms of strain amplitude limit at high cycle fatigue regime. In this paper, digital image correlation (DIC) technique is used to experimentally determine local material strains of Nitinol fatigue specimens using monotonic and cyclic loading conditions. These local strains are compared with strains computed from finite element analysis. It was found that strains from DIC and FEA are comparable in the single-phase states (pure austenitic or martensitic), whereas the measured strains can show significant difference from simulation computed strain during the transformation stage where both austenite and martensite phase co-exist. These observations have significant implications to nitinol fatigue testing and implant reliability assessment.
Published: 10 September 2021
Journal of Heat Transfer, Volume 143; https://doi.org/10.1115/1.4052198

Abstract:
Mechanistic models developed to predict partial nucleate boiling are not adequate for fully developed nucleate boiling due to differences in the prevailing heat transfer governing mechanisms. In place of the mechanistic model, several empirical correlations and semimechanistic models have been proposed over the years for the prediction of fully developed nucleate boiling as presented in this study but they are unsuitable for use in computational fluid dynamics (CFD) code. Recently, the simulation of fully developed nucleate boiling has become much more practical because of advancement in a computational method that involves the coupling of the interface capturing method (for slug bubbles) with the Eulerian multifluid model (for dispersed spherical bubbles). Nonetheless, there is a need for a mechanistic closure law for the fully developed nucleate boiling phenomenon that would complement this advancement in CFD. Toward this end, a mechanistic wall heat flux partitioning model for fully developed nucleate boiling is proposed in this study. This model is predicated on the hypothesis that a high heat flux nucleate boiling is distinguished by the existence of a liquid macrolayer between the heated wall and the slug or elongated bubbles, and that the macrolayer is interspersed with numerous high frequency nucleate small bubbles. With this hypothesis, the heat flux generated on the heated wall is partitioned into two parts: conduction heat transfer across the macrolayer liquid film thickness and evaporation heat flux of the microlayer of the nucleating small bubbles. The proposed model is validated against experimental data.
, Chunxiao Jiao, , Na Ta, Zhushi Rao
Journal of Computational and Nonlinear Dynamics, Volume 16; https://doi.org/10.1115/1.4051995

Abstract:
The double-cylinder turbines' (DCT) propulsion system is widely applied to large-scale ships, while the instability mechanism of the system lacks theoretical and scientific research. Based on gear transmission principle and finite width journal bearings theory, the lateral-torsional-axial model of the system considering multiple nonlinear and time-varying factors is established. The effects of the unsymmetrical load parameters on the stability of the coupled system have been explored and quantified. Results indicate that the phenomenon of instability gradually occurs with the increase of excitation frequency, the decrease of load ratio between the two inputs or the decrease of input load value, and the vibration of the gear pair on the low load side is more severe. Furthermore, the vibration amplitude is related not only to the load parameters but also to the distance between the gear pair and the load input disk. Finally, the influence of the oil whip on the system stability is crucial, especially when the system is in an unstable state. This study puts forward the stability boundary of the DCT propulsion system and provides a theoretical reference for the optimization and adjustment of the load parameters.
Hong Ying Li, Xi Bo Wang, Shu Meng Zhang, Jian Li
Journal of Computational and Nonlinear Dynamics, Volume 16; https://doi.org/10.1115/1.4051462

Abstract:
Nonlinear vibrations of axially moving plates partially immersed in fluid are investigated in this paper. The system has time dependency in velocity and tension in axial direction. The Galerkin method is used to solve the nonlinear vibration differential equation. The method of multiple scales and Runge–Kutta method are applied to solve the nonlinear vibration response of the system. Additionally, the stability conditions of trivial and nontrivial solutions are analyzed using the Routh–Hurwitz criterion. The effects of mean velocity, amplitude of pulsating velocity, mean tension, amplitude of pulsating tension, and pulsating frequency on the complex dynamics of the system are obtained. The study results reveal rich dynamic behaviors of fluid–structure coupling system.
Journal of Biomechanical Engineering; https://doi.org/10.1115/1.4052369

Abstract:
This paper describes the design of a simple and low cost compliant low profile prosthetic foot based on a cantilevered beam of uniform strength. The prosthetic foot is developed such that the maximum stress experienced by the beam is distributed approximately evenly across the length of the beam. Due to this stress distribution, the prosthetic foot exhibits compliant behavior not achievable through standard design approaches (e.g. designs based on simple cantilevered beams). Additionally, due to its simplicity and use of flat structural members, the foot can be manufactured at low cost. An analytical model of the compliant behavior of the beam is developed that facilitates rapid design changes to vary foot size and stiffness. A characteristic prototype was designed and constructed to be used in both a benchtop quasistatic loading test as well as a dynamic walking test for validation. The model predicted the rotational stiffness of the prototype with 5% error. Furthermore, the prototype foot was tested alongside two commercially available prosthetic feet (a low profile foot and an energy storage and release foot) in level walking experiments with a single study participant. The prototype foot displayed the lowest stiffness of the three feet (6.0, 7.1, and 10.4 Nm/deg for the prototype foot, the commercial low profile foot, and the energy storage and release foot, respectively). This foot design approach and accompanying model may allow for compliant feet to be developed for individuals with long residual limbs.
Journal of Biomechanical Engineering; https://doi.org/10.1115/1.4052371

Abstract:
Current clinical practice is often unable to identify the causes of conductive hearing loss in the middle ear with sufficient certainty without exploratory surgery. Besides the large uncertainties due to interindividual variances, only partially understood cause-effect principles are a major reason for the hesitant use of objective methods such as wideband tympanometry in diagnosis, despite their high sensitivity to pathological changes. For a better understanding of objective metrics of the middle ear, this study presents a model that can be used to reproduce characteristic changes in metrics of the middle ear by altering local physical model parameters linked to the anatomical causes of a pathology. A finite-element model is therefore fitted with an adaptive parameter identification algorithm to results of a temporal bone study with stepwise and systematically prepared pathologies. The fitted model is able to reproduce well the measured quantities reflectance, impedance, umbo and stapes transfer function for normal ears and ears with otosclerosis, malleus fixation and disarticulation. In addition to a good representation of the characteristic influences of the pathologies in the measured quantities, a clear assignment of identified model parameters and pathologies consistent with previous studies is achieved. The identification results highlight the importance of the local stiffness and damping values in the middle ear for correct mapping of pathological characteristics, and address the challenges of limited measurement data and wide parameter ranges from literature. The great sensitivity of the model with respect to pathologies indicates a high potential for application in model-based diagnosis.
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