一种估计管材硬化模型参数的方法

管材力学性能参数的准确性是影响管材塑性成形有限元数值模拟质量的关键因素之一。单向拉伸试验的试件取自滚弯和焊接等制管工序之前的平板坯料 ,所测应力—应变关系无法真实描述管材的塑性变形行为。单向拉伸试验也不能精确反映管材在实际塑性成形中所处的复杂应力状态。基于各向同性硬化假设 ,本文提出了一种轴压胀形、单向压缩试验和数据拟合技术相结合的估计管材硬化模型参数的方法。有限元数值模拟结果显示 ,由这种方法所估计出的管材硬化模型参数是相当准确的。

Estimation of the Hardening Characteristics of Tubular Material

One of the critical sets of parameters for successful finite element simulation of tube plastic deformation is the material properties. However, very little mechanical data exists for the tubular materials commomly used in the plastic forming industry.The uniaxial tension test properties, which are obtained using specimens taken from a flat sheet metal prior to roll forming and welding, inevitably change during the tube manufacturing process. In addition, uniaxial tension test fails to accurately reflect the complex stress state of tube plastic forming. Based on the isotropic hardening assumption, this paper presents a method for estimating the hardening characteristics of tubular material. The method integrates tube hydroforming process, uniaxial compression test and least squares fitting technique. Finite element simulation run with the experimental data demonstrates that the evaluated hardening constants of Krupkowsky's Law are very accurate.