闭孔泡沫铝的多轴唯象受压本构参数

基于显微计算机断层扫描影像信息, 逆向重建闭孔泡沫铝试件的三维细观有限元模型, 定量研究闭孔泡沫铝在多轴压缩载荷作用下的大变形力学行为. 讨论了泡沫金属唯象弹塑性本构参数的确定方法, 根据计算结果确定了3 个有代表性的泡沫材料本构模型的本构参数, 并验证了这些本构模型在描述多轴压缩应力状态下的精度. 研究表明, 对于单轴压缩, 3 个本构模型的屈服面均有很好的精度;对于静水压缩, 有限元软件"ABAQUS"的可压缩泡沫本构模型屈服面会发生严重偏离, 陈-卢本构模型"屈服面" 略微低估静水压缩的屈服应力, 而体积强化本构模型的屈服面有很好的精度.

MULTIAXIAL PHENOMENOLOGICAL COMPRESSIBLE CONSTITUTIVE PARAMETERS FOR CLOSED-CELL ALUMINUM FOAMS

A three-dimensional (3D) finite element model for real closed-cell aluminum foam specimen was constructed by employing the microfocus X-ray CT system, 3D reconstruction program and the commercially mesh generation program. By changing the boundary conditions of the 3D finite element models for real closed-cell aluminum foam specimen, eleven various stress states including uniaxial (sides coupling), hydrostatic and proportional compression loading were applied for analysis. The yield surface parameters of three compressible elasto-plastic constitutive models were obtained from numerical results. In testing hydrostatic compression, the crushable foam model with isotropic hardening in ABAQUS showed very serious deviation, especially at large strain levels. Chen-!-Lu constitutive models lightly underestimated the hydrostatic yield stress. The present volumetric hardening model was seem to give accurate predictions for both uniaxial and hydrostatic compressions.