Development of a multiaxial stress testing system with quasi-high strain rate for light weight materials for next generation transportation vehicles

为了精确测量准高应变率下板料的双轴应力-应变曲线，研制了伺服控制双轴应力试验机。管状试样是通过弯曲板材试样，焊接板材边缘制成的。成功地测量了冷轧中频钢板（SPCE）、铝合金板和高强度钢板的变形行为和成形极限应力和应变。此外，还成功地建立了一个能够再现试验材料在双轴拉伸下的加工硬化行为的差分加工硬化模型。实验结果与基于Marciniak-Kuczyński方法的应变局部化分析计算结果在定量上一致。由此，验证了所提出的多轴材料试验方法对于确定精确的板材本构模型是有用的。

A servo-controlled biaxial stress testing machine was developed for the accurate measurement of the biaxial stress-strain curves of sheet metals under quasi-high strain rates. Tubular specimens were fabricated by bending sheet samples and welding the sheet edges. The deformation behavior and forming limit stresses and strains of a cold rolled IF steel sheet (SPCE), an aluminum alloy sheet and a high strength steel sheet were successfully measured. Moreover, a differential work hardening model that is capable of reproducing the work hardening behavior of the test materials under biaxial tension has been successfully developed. The experimental results quantitatively agreed with those calculated using a strain localization analysis based on the Marciniak-Kuczyński approach. Thus, it has been verified that the proposed multiaxial material testing method is useful for determining accurate constitutive models for sheet metals.