Influence of Lode Angle Dependency on the Critical State for Rotational Plasticity

Coombs, W.M.; Crouch, R.S.; Augarde, C.E.

Abstract

The critical state in soils represents the condition whereby unbounded distortions occur with no change in volume. Many constitutive models incorporate this idealised asymptotic state as a fundamental feature. It has been shown experimentally that both the critical state and yield surfaces in soils exhibit a Lode Angle Dependency (LAD). A separate feature in soils is the directional bias of the material stiffness. This has been introduced into hardening plasticity models by allowing the yield surface to rotate. Extending the classical Modified Cam-Clay (MCC) model, Dafalias proposed a rotated and distorted ellipse that maintains a constant critical state stress ratio for any degree of rotation of the yield surface. He also presented the multi-axial generalised version of the yield function in which anisotropy is properly accounted for by a second order tensor. A means of satisfactorily introducing LAD, together with rotational hardening has yet to be found. This paper explores the consequences of using simple approaches to overcome this omission.

Citation

Coombs, W., Crouch, R., & Augarde, C. (2009). Influence of Lode Angle Dependency on the Critical State for Rotational Plasticity. In E. Oñate, D. R. J. Owen, & B. Suárez (Eds.), X International Conference on Computational Plasticity (COMPLAS X)

• Conference Name: Computational Plasticity X: Fundamentals and Applications (COMPLAS X)
• Conference Location: Barcelona, Spain
• Publication Date: 2009-09
• Deposit Date: Sep 13, 2011
• Book Title: X International Conference on Computational Plasticity (COMPLAS X)
• Keywords: Computational plasticity; Constitutive modeling; Critical state; Rotational hardening; Anisotropy.
• Public URL: https://durham-repository.worktribe.com/output/1157778