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.

Experimental investigation and finite element simulation of laser beam welding induced residual stresses and distortions in thin sheets of AA 6056-T4

Abstract: Laser beam welding has recently found its application in the fabrication of aircraft structures where fuselage panels, made of thin sheets of AA 6056-T4 (an aluminium alloy), are welded with stiffeners of the same material in a T-joint configuration. The present work simulates laser beam welding induced residual stresses and distortions using industrially employed thermal and mechanical boundary conditions. Various measurements performed on small-scale welded test specimens provide a database of experimental results that serves as a benchmark for qualification of the simulation results. The welding simulation is performed with the commercial finite element software Abaqus and a Fortran programme encoding a conical heat source with Gaussian volumetric distribution of flux. A sequentially coupled temperature–displacement analysis is undertaken to simulate the weld pool geometry, transient temperature and displacement fields. The material is assumed to follow an elasto-plastic law with isotropic hardening behaviour (von Mises plasticity model). A comparison between the experimental and simulation results shows a good agreement. Finally, the residual stress and strain states in a T-joint are predicted.

The plastic yield behaviour of polymethylmethacrylate

Abstract: The yield behaviour of an amorphous glassy polymer has been investigated under a system of combined stress in an attempt to define a criterion for yield. Sheets of polymethylmethacrylate were compressed in plane strain and the compressive yield stress was determined as a function of the tension applied in the plane of the sheet. The compressive yield stress was found to decrease with applied tension more rapidly than would be expected if the shear yield stress of the material were independent of pressure. The results have been analysed in terms of a Coulomb yield criterion where the shear yield stress is expressed as a constant plus a friction term proportional to the pressure on the shear plane. Birefringent shear zones were observed in the deformed region after the load was removed and these zones were inclined at 52.9° to the plane of the sheet. It was found that if the stresses at yield were expressed as nominal stresses then the inclination of the shear planes predicted by the yield stress data coincided with the observed inclination. It also appears that it may be possible to define a fracture criterion in terms of the applied stress system.