Strength difference in compression and tension and pressure dependence of yielding in elasto-plasticity

✍ Scribed by Rolf Mahnken

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 327 KB
• Volume: 190
• Category: Article
• ISSN: 0045-7825
• DOI: 10.1016/s0045-7825(00)00364-9

✦ Synopsis

A characteristic of most metallic materials is nonlinear work-hardening for the ¯ow stress, equal in tension and compression at ®rst loading. On the contrary, triaxial experimental tests for high-strength steels by Spitzig et al. [W.A. Spitzig, R.J. Sober, O. Richmond, Pressure dependence of yielding and associated volume expansion in tempered martensite, Acta Metall. 23 (1975) 885±893] and others also show a pronounced strength-dierential eect between compression and tension (S-D eect), and furthermore a sensitivity of the ¯ow stress to the hydrostatic pressure. These macroscopic phenomena are related to volume expansion of the material by the authors in [W.A. Spitzig, R.J. Sober, O. Richmond, Pressure dependence of yielding and associated volume expansion in tempered martensite, Acta Metall. 23 (1975) 885±893] as a consequence of plastic deformation. For simulation of the above observations in this work a yield function dependent on the three basic invariants of a reduced stress tensor and a process vector is proposed. Additionally the yield function is generalized towards the incorporation of a damaging void growth eect due to hydrostatic stresses. Concerning numerical aspects, the resulting local problem with 15 unknowns is reduced to an equivalent three-dimensional problem, and for the ®niteelement equilibrium iteration the algorithmic tangent operator is derived. Two examples illustrate the capability of the proposed model.