Modified MK model combined with ductile fracture criterion and its application in warm hydroforming  

基于韧性断裂准则的修正MK模型及其在充液热成形中的应用（英文）

作　　者：杨希英[1] 郎利辉[1] 刘康宁[1] 郭禅[1] 

机构地区：[1]北京航空航天大学机械工程及自动化学院,北京100191

出　　处：《Transactions of Nonferrous Metals Society of China》2015年第10期3389-3398,共10页中国有色金属学报（英文版）

基　　金：Project(51175024)supported by the National Natural Science Foundation of China

摘　　要：A modified MK model combined with ductile fracture criterion（DFC-MK model） is proposed to compute the forming limit diagrams（FLDs） of 5A06-O aluminum alloy sheet at different temperatures.The material constant（C） of ductile fracture criterion and initial thickness imperfection parameter（f0） at various temperatures are determined by using a new computing method based on wide sheet bending test.The FLDs at 20 and 200 °C are calculated through the DFC-MK model.The DFC-MK model,which includes the influence of through-thickness normal stress,is written into the subroutine VUMAT embedded in Abaqus/ Explicit.The cylindrical cup hydroforming tests are carried out to verify the model.The results show that compared with experimental observations,the predicted FLDs based on DFC-MK model are more accurate than the conventional MK model;the errors between the simulations and experiments in warm hydroforming are 8.23% at 20 °C and 9.24% at 200 °C,which verify the effectiveness of the proposed model.将MK模型与韧性断裂准则相结合,提出预测不同温度下5A06-O铝合金板材成形极限的新模型。基于宽板弯曲试验,应用新的修正MK模型确定材料常数(C)和初始厚度不均度(f0)。通过提出的新模型计算得到20和200°C下的成形极限图。将板材厚度法向应力对成形极限的影响计入新模型,并嵌入Abaqus/Explicit中,进行筒形件充液成形并加以验证。结果表明:与传统MK模型对比可知,新模型预测的成形极限图与实验值更加接近;在20和200°C下,充液热成形模拟与实验之间的误差分别为8.23%和9.24%,验证了模型的有效性。

关 键 词：MK model ductile fracture criteria warm hydroforming through-thickness normal stress 

分 类 号：TG146.21[一般工业技术—材料科学与工程]