CALIBRATION OF ANISOTROPIC YIELD CRITERIA USING UNIAXIAL TENSION TESTS AND BENDING TESTS

A method for calibration of anisotropic yield criteria based on yield stresses obtained in tensile and bending tests is developed. It is thu s possible to calibrate anisotropic criteria by means of simple tests without using the R-ratios in combination with the associated flow rul e. Explicit formulas are derived for the calibration of Hill's yield c riterion, while a numerical procedure is developed for calibration of the Barlat and Lian yield criterion. Results from tensile and bending tests on the aluminium alloy AA 7108 in temper T76 are presented. Test s in three material directions are carried out in order to characteris e the plastic anisotropy of the alloy. In the tensile tests the stress -strain curves and the R-ratios are determined, whereas the bending te sts establish the moment-curvature curves. (C) 1998 Elsevier Science S .A. All rights reserved.