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.

Dynamic Indentation of an Elastic-Plastic Multi-Layered Medium by a Rigid Cylinder

Abstract: A plane-strain analysis of dynamic indentation of an elastic-plastic multi-layered medium by a rigid cylinder was performed using the finite element method. Conversely to plane-strain static contact analysis, the solutions of a dynamic contact analysis within a subsurface domain adjacent to the contact region are independent of mesh size, provided the mesh dimensions are sufficiently large such that the propagating waves reflected from the artificial boundaries do not reach the domain of interest during the analysis. Simulation results for the normal force, contact pressure distribution, subsurface stresses, and evolution of plasticity in the multi-layered medium are presented in terms of the speed and radius of the rigid indenter. The likelihood of mechanical failure due to excessive plastic deformation and cracking is interpreted in terms of finite element results for the von Mises equivalent stress, first principal stress, and equivalent plastic strain obtained for different values of the indenter speed and radius of curvature.

Stress distribution on a three-unit implant-supported zirconia framework. A 3D finite element analysis and fatigue test.

Abstract: Purpose: The purpose of this study was to investigate, by finite element analysis (FEA) and fatigue analysis, the influence of different loading conditions on the stress distribution in a 3-unit implant-supported Y-TZP fixed partial denture (FPD). Material and methods: A three-dimensional FEM model was developed. The materials used in this study were assumed to be linearly elastic, homogeneous and isotropic. 100 N and 300 N loads over a 0,5 mm2 areas with different angles (0°, 15° and 35°) and locations were applied on the prosthesis and the distribution of equivalent von Mises stress was investigated. A fatigue analysis was carried out too. Results: maximum stresses were found at the connector region of the framework when the intermediate element is loaded (100 N load pattern: 32,9 MPa, 33 MPa and 51,8 MPa; 300 N load pattern: 98,6 MPa, 102,8 MPa and 155,7 MPa, respectively with 0°, 15° and 35° of inclination). Results confirmed the vulnerability of both connector areas even if just one pillar was loaded with an increase in stress when angle of load inclination is larger. The cyclic fatigue evaluation indicates a strong propensity for fatigue behavior, presenting a considerable range of loading conditions. No fracture fatigue occurred with a 100 N force. A 300 N force applied to the pontic produces no fatigue problems because the load is equally shared by whole system. A 300 N force applied to one of the two pillars, or to both implants generates fatigue problems. Conclusion: F.E.M. analysis of a 3-unit implant-supported Y-TZPFPD, give accurate information about loading conditions for clinical success over time. Fatigue analysis results show structural reliability of the Y-TZP as framework material for 3-unit posterior FPDs.

Nylon-6/rubber blends, Part III: Stresses in and around rubber particles and cavities in a nylon matrix

Abstract: The stress field around a rubber particle and a cavitated particle in a nylon/rubber blend has been studied using an analytical and a finite element approach. Attention was paid to the influence of the mechanical properties of the dispersed phase and the applied stress state. The results show that the choice of the bulk modulus of the elastomer is crucial. It appeared that especially with a triaxial stress, the Von Mises stress increased strongly upon cavitation (a more than five-fold increase close to the particle) while the hydrostatic stress only increased slightly. Also, the stresses in particles in the neighbourhood of a cavity have been calculated. Stresses in particles lying in or close to the equatorial plane of the cavity were higher than stresses in the other particles

Evaluation of stress distribution in overdenture-retaining bar with different levels of vertical misfit.

Abstract: Purpose: To evaluate the effects of different levels of vertical misfit between implant and bar framework on distribution of static stresses in an overdenture-retaining bar system using finite element analysis. Material and Methods: A 3D finite element model (11,718 elements and 21,625 nodes) was created and included two titanium implants and a bar framework placed in the medial region of the anterior part of a severely reabsorbed-jaw. All materials were presumed to be linear elastic, homogenous, and isotropic. Mechanical simulation software (NEiNastran 9.0) was used, where displacements were applied on the end of the bar framework to simulate the closure of the vertical misfits (5, 25, 50, 100, 200, and 300 μm) after tightening of the screws. 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 stress to the misfits studied. While in the bar framework, retaining-screw neck, and implant platform, a considerable stress increase proportional to the misfit amplification was observed. Conclusions: The different levels of vertical misfit did not considerably influence the static stress levels in the peri-implant bone tissue; however, the mechanical components of the overdenture-retaining bar system are more sensitive to lack of passive fit.