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

作者：Yang Xi ying; Lang Li hui^*; Liu Kang ning; Guo Chan

来源：Transactions of Nonferrous Metals Society of China, 2015, 25(10): 3389-3398.

DOI：10.1016/S1003-6326(15)63974-7

• MK model
• ductile fracture criteria
• warm hydroforming
• through-thickness normal stress

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 (f(0)) at various temperatures are determined by using a new computing method based on wide sheet bending test. The FLDs at 20 and 200 degrees 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 degrees C and 9.24% at 200 degrees C, which verify the effectiveness of the proposed model.

• 出版日期2015-10
• 单位北京航空航天大学