裂纹尖端弹塑性变形的实验测量与有限元计算

COMPARISON OF FINITE ELEMENT CALCULAION AND EXPERIMENTAL STUDY OF ELASTIC-PLASTIC DEFORMATION AT CRACK TIP

用显微网格数字图像处理方法，测量了Ｆｅ－Ｓｉ材料平面应力条件下Ⅰ型单边裂纹尖端附近的应变场，并且用弹塑性有限元程序进行了数值模拟。对实测结果和有限元计算模拟结果进行了对比分析。结果表明：逐级更新拉格朗日坐标体系下的弹塑性有限元计算在裂纹尖端不出现严重钝化和损伤的条件下，可以正确反映裂尖区域的弹塑性变形。在裂纹接近临界扩展时，有限元计算与实测结果之间有较大差别，其原因有待进一步研究。

The strain field around a mode Ⅰ crack tip with plane stress deformation forFe-0.5%Si material specimen was measured by SEM,micro grid method and digital imageprocessing. Finite element method(FEM) for elastic-plastic deformation was used to cal-culate the experimental object. Comparison of experimental and FEM results showed thatFEM based on the updated Lagrangian formulation was in good accordance with experi-mental measurement.But some factors,e.g.,plastic dilatancy,should be included as cracktip was nearly to extend.