Refine Search

New Search

Results: 4

(searched for: doi:10.1016/j.tws.2019.106284)
Save to Scifeed
Page of 1
Articles per Page
by
Show export options
  Select all
Published: 16 November 2021
by MDPI
Abstract:
A method for image analysis was implemented to determine the edge pixels of two biopolymer-based thermoplastic filaments during their hot melt isothermal sintering at 120 °C. Successive inverted ellipses are adjusted to the contour of the sintered filaments and lead to the identification of the parameters of the corresponding lemniscates of Booth. The different steps of the morphological image analysis are detailed, from 8-bit coded acquired images (1 frame/s), to the final fitting of the optimized mathematical functions describing the evolution of the filaments envelope. The complete sequence is composed of an initial pure viscous sintering step during the first minute, followed by viscoelastic swelling combined with melt spreading for a longer time, and then the stabilization of the sintered filaments shape for over 2 min at high temperatures. Using a master curve obtained from Hopper’s abacus, the characteristic viscous sintering time is assessed at tvs = 78 s, confirming the one previously found based on the measurement of the bonding neck length alone. Then, the full description of the evolution of the thermoplastic filaments envelope is assessable by image analysis during sintering trials as a result of its digital modeling as successive lemniscates of Booth, reflecting geometry changes in the molten state.
Jian Zhang, Mingqiang Dai, , Wenxian Tang, Xilu Zhao
International Journal of Pressure Vessels and Piping, Volume 193; https://doi.org/10.1016/j.ijpvp.2021.104435

The publisher has not yet granted permission to display this abstract.
Stepan V. Cheremnykh, Sergei A. Sokolov
Vestnik MGSU, Volume 16, pp 577-586; https://doi.org/10.22227/1997-0935.2021.5.577-586

Abstract:
Introduction. It is necessary to improve methods of analysis of the limit states, occurring when a thin-walled shell is in the elastoplastic domain, to use these cylindrical shells as elements of heavily loaded products of construction and machine building industries. Materials and methods. The problem of stability of a circular thin-walled cylindrical shell, made of steel 45 GOST 1050-2013, that takes the load induced by pure compression and axial torsion, has been studied. Besides, experimental and theoretical components of the problem have been analyzed. Experimental facility SN-EVM was applied to perform an experiment test and analyze its findings in terms of different versions of the theory of plasticity used to solve shell stability problems beyond the elastic limit. The co-authors emphasize the unavailability of any definition of the criterion of stability loss under combined loading based on experimental dependences that were identified earlier. The results of the experiment were compared with the results of the theoretical study. The analysis of the shell stability in the case of complex subcritical loading are based on the A.A. Ilyushin theory of stability, in which plasticity functions are taken according to V.G. Zubchaninov’s approximations. Results. The problem was solved using the software programme, developed by the co-authors. The software solves the bifurcation problem of a cylindrical shell with regard for the complex nature of deformations at the moment of stability loss in the case of exposure to complex subcritical loading, commensurable processes and the trajectory that has the form of circular arcs. It has been shown that the proposed method of analysis and approximations describe the real stress-strain state of shells that feature low flexibility in respect of a complex pattern of deformation and characterize a stable state of the material beyond the elastic limit. Conclusions. The theoretical strength and deformability analysis of a cylindrical shell and its experimental studies demonstrate sufficient convergence which proves their reliability. This conclusion will allow to improve the process of design of structural elements made of materials that have complex mechanical properties.
Page of 1
Articles per Page
by
Show export options
  Select all
Back to Top Top