Prediction And Control Of Fracture In Multi-point Press Forming Of Aluminum Alloy Integral Panel

Aluminum alloy integral panel has a series of advantages, such as high efficiency, light weight, high strength, and so on. As a kind of structural support, the integral panel is more and more widely used in aircraft fuselage, wing, rocket tank, space station and so on. Due to the special structure of the aluminum alloy integral panel, it is easily to generate crack defects in forming process.Multi-point press forming is a flexible processing method with high forming efficiency. This paper mainly study the punch size, forming times and variable forming path on crack in multi-point press forming of aluminum alloy integral panel. Specific content as follows:1. Through the uniaxial tensile test and plane tensile test of aluminum alloy material 7B04-T7451 calculated the anisotropy of the material yield stress ratio parameters and other parameters, established the material model of 7B04-T7451. The tensile test and plane tensile test process was simulated, the strain of tensile specimens were measured and the material parameters in the ductile fracture criterion were obtained.2. Press bending forming experiment and simulations of aluminum alloy integral panel were conducted.Using python to write ductile fracture criterion programs and finding suitable ductile fracture criterions. The experiments of Aluminum Alloy integral panel multi-point press forming were conducted and the microstructure of cracks were observed. The experimental process was simulated, the stress and strain data of the simulation results were calculated by the script programs, and the distribution of the integral value of the ductile fracture criterion was obtained.3. The relationship between the punch size and the stress and strain distribution of the aluminum alloy integral panel was studied, the relationship between the punch size and crack location was also studied. Studied the forming methods on the distribution of stress and strain of the aluminum alloy integral panel. The relationship between the forming method and the location of the crack was studied.4. The effect of deformation on crack generating and stiffener buckling of aluminum alloy integral panel were studied.The influence of the forming times on crack generating was studied, and the results show that reasonable forming times can significantly reduce the probability of crack generation. The effect of deformation path on crack generating was studied, and the results show that the reasonable deformation path can significantly reduce the risk of the crack generation. Multi-steps forming and continuous variable path forming can effectively reduce or restrain crack generating of aluminum alloy integral panel in multi-point press forming.