| In recent years, in order to reduce energy consumption and environmental pollution effectively, light weight has become the main trend of modern structural design. Especially represented by high-strength aluminum alloy material, the application of the lightweight and high strength materials in advanced manufacturing field, such as automotive, aerospace etc, is increasing. Warm deep drawing of high-strength aluminum alloy sheet not only meets the demands on the environmental protection and the lighter trend of products, but also can remarkably improve the qualification of the products. The techniques of warm forming of high-strength aluminum alloy have been paid more and more attentions in recent years. However, the process of warm deep drawing of high-strength aluminum alloy sheet involving many processing parameters is a nonlinear producer of multi-fields coupled. Process design adopting try-and-error methods already have been unable to meet modern production requirements, in terms of time and economy. So quantitative design of process based on numerical simulation is the right development trend in the near future. At present, most investigations about the mechanical property, microstructure and heat treatment process of high-strength aluminum alloy are focused. Few efforts are made on experimental and theoretical investigation of warm forming of high-strength aluminum alloy sheet. So at the background of lightweight, the research of warm deep drawing of high-strength alloy sheet has a great meaning for grasping the forming disciplines and making a scientific and rational deep drawing process.7075-T6 high-strength aluminum alloy, whose comprehensive property is better, is one of the highest strength aluminum alloys using in our country. In this thesis, 7075-T6 high-strength aluminum alloy sheet is the main investigated subject. In generally adopting the combination research method of experiment and numerical simulation, the investigations are divided into two parts: basic experiment and forming theory. In this thesis, the mechanical behavior of warm deformation of 7075-T6 high-strength aluminum alloy sheet is analyzed through the uniaxial tension tests in three different strain rates at 50℃~280℃. The constitutive model and yield function are constructed based on the experiment data. The FLD of 7075-T6 high-strength aluminum alloy sheet at the warm conditions is obtained through the forming limit experiment. Using the material parameters and the forming limit experiment condition as the boundary condition, the finite element model is constructed by ABAQUS. The simulated FLD is got by the calculation with the finite element model. A ductile fracture criterion of 7075-T6 high-strength aluminum alloy sheet considering temperature effect is put forward. The material parameters and the critical values are calculated by the combination method of experiment and FE simulation.The research of this thesis is helpful to extend the application field of forming technology of high-strength aluminum alloy sheet, and develop the warm forming theory. It can promote the application of warm forming technology of high-strength aluminum alloy sheet. |
