基于液压胀形实验及增量理论构建管材本构关系

Determination of constitutive relationship of tubular materials based on incremental theory and hydraulic bulge test

为了准确构建管材本构关系,提出一种新的依据管材液压胀形实验数据、运用增量理论构建管材本构关系的方法。通过采用三维应变测量分析系统在线实时测量管材胀形实验中胀形区的三维位移场,并通过计算获得三维应变场、壁厚减薄等,避免了对管材胀形轮廓形状的预先假设。为了验证提出方法的可靠性,将运用增量理论、全量理论及单向拉伸实验确定的管材材料参数分别用于管材液压胀形实验的有限元模拟,并将模拟得到的管材的最大胀形高度、胀形轮廓形状与实验结果进行对比。结果显示,基于增量理论法获得各项结果的偏差均最小,在6.7%范围以内,故基于增量理论的方法能更准确地预测管材材料的本构关系。

In order to determine constitutive relationship of tubular materials accurately, a novel approach was proposed by means of the incremental theory based on the data of tube hydraulic bulge test. The three-dimensional displacement field of the bulging zone was meas- ured on-line and real-time via three-dimensional strain measurement system in the test, and then the strain field and wall thickness thinning were obtained through the calculation. Thus, the pre-assumption of bulged profiles was avoided. Finite element simulations of tube hydraulic bulge with the material parameters which were determined by increment theory, total strain theory and uniaxial tensile test respectively, were performed to obtain the maximum bulge height and bulge profiles, and they were compared with those obtained by the test to verify the reliability of the proposed approach. The results show that the deviations of those results obtained by means of incremental theory are the smallest, which are in a range of less than 6. 7%. That is to say, the approach by means of the incremental theory can pre- dict the constitutive relationship of tubular material more precisely.