Abstract:The effects of interfacial adhesion strength between skin sheet and core polymer on the formability of AA5052/ polyethylene/AA5052 sandwich sheets was investigated. A numerical simulation model considering the interface conditions between skin sheet and core materials was developed for simulating the forming process of sandwich sheet. Comparisons between the experimental results and calculations verify the proposed model. Then, the rigid punch tests and the NAKAZIMA forming tests were carried out for sandwich sheets with three kinds of interface conditions (separation, adhesion and stick). The influences of interfacial adhesion strength on the damage behavior of skin sheet and the forming limit diagrams (FLD) of sandwich sheets were investigated. The results show that the interface stress can suppress the increasing of void volume fraction and then postpone the fracture of skin sheet. The FLD of sandwich sheet with stick interfacial condition is higher than those of sandwich sheets with adhesion and separation interfacial conditions. It can be concluded that the FLD of sandwich sheet shifts to higher value with the increasing of interfacial adhesion strength.

Key words: sandwich sheets; formability; interfacial adhesion strength; aluminum; polyethylene; numerical method, damage model