Forming limit prediction for two-stage aluminum alloy sheet forming process considering the effect of normal stress

Abstract

Purpose

The purpose of this paper is to analyze theoretically the influence of normal stress on the formability of aluminum alloy sheets in non-linear strain paths.

Design/methodology/approach

Four loading modes of non-linear strain paths are investigated in detail to consider the effect of normal stress on formability of aluminum alloy sheets.

Findings

Results show that the influence of normal stress in the first stage can be ignored. However, the normal stress in the second stage enhances the formability of aluminum alloy sheets obviously. Besides, the normal stress in the second stage is found to have larger effect on forming limit stress than that in the first stage.

Research limitations/implications

Maybe more experiment data should be obtained to support the theoretical findings.

Originality/value

This current study provides a better understanding of normal stress effect on the formability of aluminum alloy sheets in non-linear strain paths. Since the reacting stage of normal stress play important roles in normal stress effect on the formability of aluminum alloy sheets, the insight obtained in this paper will help to judge the instability of aluminum alloy sheets in complex forming processes with normal stress reacting on the sheet or tube.

Citation

Zhang, F., Chen, J. and Chen, J. (2016), "Forming limit prediction for two-stage aluminum alloy sheet forming process considering the effect of normal stress", Engineering Computations, Vol. 33 No. 4, pp. 1192-1204. https://doi.org/10.1108/EC-07-2015-0185