応力三軸度がアルミニウム合金薄板の破断ひずみに与える影響

抄録

The major issue of the aeronautical field is to deal with a constant weight reduction, while keeping the same or increasing the safety. Impact of accidental fragments on aircraft bodies have to be considered for the design of aircraft. The use of numerical simulation to predict the behavior of structures has seen an exponential expansion since the last years. It has become an essential tool to reduce developing time and cost, especially, material parameters are very important for high accuracy of computer simulations. Fracture strain is important to simulate fracture behavior and locus. It is now established that the stress triaxiality clearly affects fracture strain of ductile materials, but details and important factors were still unknown. The effects of stress triaxiality on fracture strain of aluminum alloys have been studied. However, the amount of data related to aluminum alloys is still low. The effects of stress triaxiality, Lode angle parameter and strain rate are not fully clarified. Hence, effects of stress triaxiality on fracture strain of aluminum alloy 2024-T3 were measured using plate-type specimens. Fracture strain was accurately measured using 2D-digital image correlation (DIC) method. Numerical simulations under the same conditions were carried out using finite element code LS-DYNA. Fracture strain decreases as stress triaxiality increases. Numerical simulations were good agreement with the experimental results.