A simple approach to the description of multiaxial cyclic stress-strain relationship

The multiaxial cyclic stress-strain relationship under both proportional an d nonproportional loading was studied according to the characteristic of th e stress-strain on the critical plane and the research results of multiaxia l critical plane principle. The multiaxial cyclic stress-strain model under proportional loading is first derived based on the uniaxial cyclic stress- strain relationship. The normal strain excursion between adjacent turning p oints of the maximum strain and the maximum shear strain amplitude on the c ritical plane are then combined as an equivalent strain amplitude by von Mi ses criterion to replace the equivalent strain amplitude of the proportiona l loading, which takes account of the effect of additional hardening due to nonproportional loading. As this result shows, a simple multiaxial cyclic stress-strain relationship is obtained for nonproportional loading. The exp eriments under the tension-torsion proportional and nonproportional cyclic loading were conducted to verify the multiaxial cyclic stress-strain model proposed in this paper. Thr: prediction has a good correction with the expe rimental results. (C) 2000 Elsevier Science Ltd. All rights reserved.