World Journal of Mechanics

Journal Information
ISSN / EISSN : 2160-049X / 2160-0503
Published by: Scientific Research Publishing, Inc. (10.4236)
Total articles ≅ 330
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Latest articles in this journal

Ryuhei Yamaguchi, Makoto Ohta
World Journal of Mechanics, Volume 12, pp 17-40;

This review considers unexpected destructive disasters involving fluid power plants, such as nuclear electric power plants and fluid power plants. It specifically addresses the possibility of fluid vibration induced in a pipeline network of such a plant. The authors investigate the flow oscillation induced within a T-junction for laminar steady flow at a Reynolds number less than 103 and clarify that there is a periodic fluid oscillation with a constant Strouhal number independent of several flow conditions. Generally, a nuclear electric power plant is constructed using straight pipes, elbows, and T-junctions. Indeed, a T-Junction is a basic fluid element of a pipeline network. The flow in a fluid power plant is turbulent. There are peculiar flow phenomena that occur at high Reynolds numbers, which are also seen in other flow situations; e.g., Kaman vortices are observed around a circular cylinder in low Reynolds numbers, around structures like bridges and downstream of islands in oceans. Although the flow situation of a T-junction and elbow in a fluid power plant, such as the fluid suddenly changing its flow direction is turbulent flow, the authors mention the possibility of the fluid-induced vibration of a pipeline network.
Hechmi Khlifi, Adnan Bourehla
World Journal of Mechanics, Volume 12, pp 1-16;

The incompressible models for the pressure-strain correlation are unable to correctly predict the turbulence flows evolving with significant compressibility. Huang and Fu use a damping function of the turbulent Mach number to modify two numerical coefficients of the incompressible model for the pressure strain developed by Launder, Reece and Rodi. This model predicts the spreading rate and the shear stress behavior in compressible turbulent mixing well. However, the model does not show the well-known compressibility effects on the compressible homogenous shear flow. In the present work, the model of Huang-Fu is revised, all resulting model coefficients become dependent on the turbulent Mach number, the gradient Mach number and the convective Mach number. The proposed model is tested in different compressible turbulent homogeneous shear flow and mixing layers cases. In general, the predicted results from the proposed model are in an acceptable agreement with DNS and experiment data.
Hiroyuki Furukawa, Takeomi Yamazaki
World Journal of Mechanics, Volume 12, pp 41-50;

In previous studies, the effects of radial clearance on the flow of a rotating disk in a cylindrical vessel have been investigated by using rotating disks of different shapes. As a result, different flow phases were observed in each disk due to the difference in disk dimensions. In this study, we focus on the end-face effect and conduct experiments to visualize the vortex growth process and elucidate the generation mechanism of the vortex structure. From the experiment results, at Re = 4000, 7000, and 9000, four types of vortex flow modes appeared in the vortex development process. However, at Re = 4000, only regular 2-cells and regular 4-cells appeared, and at Re = 9000, only mutated 2-cells and mutated 3-cells appeared. In addition, it was found that only one type appeared depending on the rotational ascent time ts. When Re = 4000, the rotational ascent time ts = 0, 2, 7, and 8 was stable at regular 4-cells, while the others were finally stable in regular 2-cells. This study revealed the influence of the acceleration of the rotating disk on the non-unique flows in the cylindrical casing.
Zhonggang Li
World Journal of Mechanics, Volume 11, pp 53-70;

This article has demonstrated the possibility of deriving an equivalent mathematical velocity expression while setting aside the concepts of displacement and time. The proposed velocity formula, better aligned with reality, allows a better understanding of the equivalence of matter and energy, which are comprised of the same type of basic particles. Why, then, is there a significant difference between matter and energy? This is because the combination of the basic particles is not the same. Basic particles are the basic unit of mass and energy, meaning mass and energy conservations are essentially the conservation of these basic particles. Electrons, photons, neutrons, protons, neutrinos, and other microscopic particles also consist of these basic particles. The basic particles are also the basic foundation of force: a basic particle force is the smallest force in the universe, implying that force is not continuous, but a basic particle force is the smallest unit of force. The total mass of a moving body increases with increasing velocities, and this added mass is composed of the basic particles provided by an external system. These basic particles are the foundation of the universe, and determine that physical concepts are vectors or scalars. Velocity, a vector, is the ratio between the basic particles. The concept of time is essentially academic. Although relativity equations may satisfy mathematical principles, they may represent a mathematical model with no physical meaning, not demonstrating objective physical facts.
Tomoaki Yamazaki, Gaku Tanaka, Ryuhei Yamaguchi, Yodai Okazaki, Hitomi Anzai, Fujimaro Ishida, Makoto Ohta
World Journal of Mechanics, Volume 11, pp 71-82;

Initiation, growth, and rupture of cerebral aneurysms are caused by hemodynamic factors. It is extensively accepted that the cerebral aneurysm wall is assumed to be rigid using computational fluid dynamics (CFD). Furthermore, fluid-structure interactions have been recently applied for simulation of an elastic cerebral aneurysm model. Herein, we examined cerebral aneurysm hemodynamics in a realistic moving boundary deformation model based on 4-dimensional computed tomographic angiography (4D-CTA) obtained by high time-resolution using numerical simulation. The aneurysm of the realistic moving deformation model based on 4D-CTA at each phase was constructed. The effect of small wall deformation on hemodynamic characteristics might be interested. So, four hemodynamic factors (wall shear stress, wall shear stress divergence, oscillatory shear index and residual residence time) were determined from the numerical simulation, and their behaviors were assessed in the basilar bifurcation aneurysm.
Wenhua Lv, Mao Pang, Shunping Li, Miaolong Cao
World Journal of Mechanics, Volume 11, pp 34-51;

In order to solve the problems of rolling forming accuracy and fillet thinning of alloy steel rim, a three-dimensional model of three pass rolling process was established, and the influence of different process parameters on forming quality was analyzed by using the finite element software, and the optimal process parameter combination was obtained. On this basis, the simulation results of wheel rim stress and strain for each pass rolling are analyzed, and the particle tracking technology is introduced to analyze the variation rule of stress in each incremental step. Finally, the simulation and experimental results show that the simulation thickness is basically consistent with the actual thickness, which improves the accuracy of rim rolling forming, and further verifies the correctness of rolling process simulation.
Naiyanut Jantepa, Surasak Suranuntchai
World Journal of Mechanics, Volume 11, pp 17-33;

Plastic flow behavior of the SNCM8 steel was investigated by performing hot compression tests within the temperature range of 850˚C to 1200˚C and strain rates of 0.01 s−1 to 10 s−1. Constitutive modeling based on dynamic recrystallization was established, in which Cingara equation was applied to represent work hardening up to peak stress and Avrami equation to describe dynamic softening beyond peak stress up to steady state. It was found that stress-strain responses predicted by the combined model fairly agreed with experimentally resulted curves for the particular conditions. The correlation coefficient (R) of 0.9485 and average absolute relative error (AARE) of 2.3614% was calculated for the modeled flow curves.
Xiaochen He, Jingyi Shao, Jianhao Feng
World Journal of Mechanics, Volume 11, pp 111-120;

The introduction of residual stress during the processing of materials has an important impact on the properties of the materials, so it is important to accurately measure the residual stress of the material. This paper established a finite element model of spherical indentation under the action of non-equivalent biaxial residual stress. Then we extracted the full-field accumulation state near the indentation under different stress states from the simulation results and summarized the pile height distribution near the indentation under different stress states. From the simulation, we found that the maximum pile-up height near the indentation point presented a regular trend.
Rogers Omboga Amenya, Johanna Kibet Sigey, Geoffrey Moriaso Ole Maloiy, David Mwangi Theuri
World Journal of Mechanics, Volume 11, pp 165-175;

The study investigated the effect of the angular position of the head on the blood flow in the jugular vein of giraffes. The vein considered is elastic and collapsible such that its cross-sectional area is not uniform. Transmural pressure causes the blood to move along the vein. Mathematical equations describing the flow were developed, and the vein was considered to be inclined at an angle φ to the horizontal. A finite-difference scheme was used to solve the equations of motion for the flow. The results are presented via relevant tables and plots. Our findings show that a change in the position of the head causes variation in the external pressure, which in turn causes variation in the cross-sectional area of the vein. Moreover, a drop (or increase) in the inertial pressure of the blood may cause the vein to collapse (or distend), which again triggers a change in the pressure.
Redouane Lombarkia, Augustin Gakwaya, Denis Nandlall, Marie-Laure Dano, Julie Lévesque, Ameur BenKhelifa, Philippe Vachon-Joannette, Philippe Gagnon
World Journal of Mechanics, Volume 11, pp 121-145;

Despite years of governmental and academic institutions’ researches, no experimental standards are established for evaluating crush Specific Energy Absorption SEA for plain weave fabric woven carbon-fiber-reinforced composites used in modern aircraft structures as elements of the boxes to mitigate damage during crush events. At the laboratory scale, this paper proposes a comparative study of energy absorption capability of flat plate coupons made by CFRP plain weave fabric composites. A new fixture design and setup were created with hydraulic pressure and drop tower machines to carry out tests of flat plate composite specimens under quasi-static and low velocity on-axis crash loading. For investigating parameters sensibility of triggers and layups, numerical and experimental results of four trigger types and three stacking sequences were compared. A confrontation between experimental and pre-developed UL-Crush numerical material model results confirms that coupons with 0˚ oriented central plies and saw teeth or corrugated triggers dissipates higher energy during crush, compared to coupons with 90˚ or 45˚ oriented central plies and chamfer 45˚ or steeple triggers. An efficient and simplified experimental methodology was developed to measure and investigate different parameters influencing SEA of composites under crush load. Comparison between experimental and UL-Crush material model confirms the performance of such simulation tool.
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