von Mises yield criterion

About: von Mises yield criterion is a research topic. Over the lifetime, 4374 publications have been published within this topic receiving 82642 citations. The topic is also known as: Von Mises stress.

Nonlinear model of skin mechanical behaviour analysis with finite element method.

Abstract: Background/aims: A problem commonly encountered in plastic and reconstructive surgery is the prediction of the stress put on the skin when various types of skin flaps are used. Methods/results: We developed a mathematical model based on the finite element method, in order to determine the stress field, by simulating the mechanical behaviour of human skin during wound closure. We chose to take into account the low compressive strength by modifying the mechanical parameters of the model at each step of the calculation. The model has been developed and tested on a diamond-shaped incision and applied on a Limberg incision. Conclusion: The results presented are the Von Mises stress in the area of skin around the scar and, when possible, the resultant closure force. They show the relevance of the method.

Explicit dual stress-strain and strain-stress relations of incompressible isotropic hyperelastic solids via deviatoric Hencky strain and Cauchy stress

Abstract: It is demonstrated that of all finite strain measures there is one and only one able to realize fully uncoupled separation of the volumetric and the isochoric deformation in a natural, additive manner. This unique measure is Hencky’s logarithmic strain, and its remarkable property is utilized to establish dual stress-strain and strain-stress relations for isotropic, incompressible hyperelastic solids. It is indicated that the deviatoric Hencky strain and the deviatoric Cauchy stress are derivable straightforwardly from two dual elastic potentials with respect to each other. Further, the three basic invariants of Hencky’s strain naturally reduce to two in the case of incompressibility, and these two invariants may be used to express the isotropic elastic potential. This results in simple, explicit dual representations for the foregoing dual stress-strain and strain-stress relations. In particular, it is shown that the Cauchy-Green deformation tensor can be explicitly derived from a complementary potential as function of the basic invariants of the deviatoric Cauchy stress, which automatically satisfies the hyperelasticity condition, the isotropy condition, and the incompressibility condition.

Influence of Material of Overdenture-Retaining Bar with Vertical Misfit on Three-Dimensional Stress Distribution

Abstract: Purpose: This study evaluated the effects of different bar materials on stress distribution in an overdenture-retaining bar system with a vertical misfit between implant and bar framework. Materials and Methods: A three-dimentional finite element model was created including two titanium implants and a bar framework placed in the anterior part of a severely reabsorbed jaw. The model set was exported to mechanical simulation software, where displacement was applied to simulate the screw torque limited by 100-μm vertical misfit. Four bar materials (gold alloy, silver-palladium alloy, commercially pure titanium, cobalt-chromium alloy) were simulated in the analysis. Data were qualitatively evaluated using Von Mises stress given by the software. Results: The models showed stress concentration in cortical bone corresponding to the cervical part of the implant, and in cancellous bone corresponding to the apical part of the implant; however, in these regions few changes were observed in the levels of stress on the different bar materials analyzed. In the bar framework, screw, and implant, considerable increase in stress was observed when the elastic modulus of the bar material was increased. Conclusions: The different materials of the overdenture-retaining bar did not present considerable influence on the stress levels in the periimplant bone tissue, while the mechanical components of the system were more sensitive to the material stiffness.