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

为了准确测量准高应变率下金属板材的双轴应力应变曲线，研制了一台伺服控制双轴应力试验机。管状试件是通过弯曲板材试件和焊接板材边缘制成的。成功地测量了冷轧IF钢板(SPCE)、铝合金钢板和高强度钢板的变形行为和成形极限应力应变。此外，还成功地建立了能够再现试验材料在双向拉伸下的加工硬化行为的差动加工硬化模型。实验结果与基于Marciniak-Kuczyń方法的应变局部化分析的计算结果定量一致。从而验证了所提出的多轴材料试验方法对于确定准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.