韧性断裂机理的理论探讨与基于铝合金薄板韧性断裂准则的修正

对韧性材料的断裂机理进行理论研究.当裂纹尖端附近两个相邻的材料微单元体的破坏面共面或共线时,裂纹可以通过破坏面扩展并传递到相邻的单元;当两个单元体的破坏面与两单元体中心线成一定角度时,两单元体之间将产生相对滑动或旋转,使得两破坏面之间重新共面或共线,从而使得裂纹可以扩展,形成一个连续的裂纹开裂面.基于铝合金6063薄板修正韧性材料的断裂准则,并用简单的平面应力状态下的平板拉伸试验和平面应变状态下的缺口拉伸试验,结合有限元ABAQUS计算求得韧性断裂准则中的材料常数.

Theoretical inquiry into ductile fracture mechanism and modification of ductile fracture criterion based on aluminum alloy sheet

The ductile fracture mechanism of ductile materials was theoretically investigated.If the fracture surface between two adjacent cells close to the crack tip was co-planar or co-linear,the cracks would propagate and transfer to the adjoining cell through the fracture surface.If the fracture surface was located at an angle to the midline of the adjoining cells,the two cells would slip or rotate relatively,making the fracture surface co-planar or co-linear newly.Therefore,the crack could propagate,forming a continuous fracture surface.At the same time,the fracture criterion of ductile materials was modified based on 6063 aluminum alloy sheet.The materials constants of ductile fracture criterion were obtained by using planar tensile in the tests condition of plane stress and the notch tensile tests in the condition of plane strain combined with FEM ABAQUS calculation.