基于GTN模型的20钢孔洞扩张比数值模拟

SIMULATION OF VOID GROWTH RATIO OF 20 STEEL BASED ON GTN MODEL

孔洞扩张比VG可以作为描述钢材损伤时微孔洞演化情况的细观损伤变量,GTN模型可用于金属塑性材料的细观损伤有限元模拟。应用GTN模型模拟20钢圆棒型缺口试件拉伸过程的不同阶段,得到细观损伤参量应力三轴度Rσ、等效塑性应变εp、孔洞体积百分数f及孔洞扩张比VG在试件中心截面的变化规律。结果表明:在整个拉伸过程中,上述参数的数值随着载荷的增加而增大,且εp对VG的影响较大。当试件断裂时,试件缺口截面中心位置的细观损伤参量值大于缺口根部的值,此时20钢的临界孔洞扩张比VGC为3.134。

Void growth ratio VGc can be used as a parameter of meso-damage to describe the evolution of voids, GTN model can be used to simulate meso-damage of plastic material. The paper simulates the evolution of meso-damage parameters of 20 steel in different tensile stage using GTN model. The resuhs show that with the loads increasing, stress triaxiality Rσ, equivalent plastic stain εp, void volume fraction f and void growth ratio VG tend to increase, and εp plays a significant impact on VG. When the specimen fracture, the meso-mechanical damage parameters at the center of the section with notch of specimen are bigger than what at notch root and the corresponding value of VGc of 20 steel is 3.134.