The Research On Cold-formed Residual Stress

The cold-formed residual stress is a self-balance force, which is produced by plastic deformation in the production of components and manufacturing process before suffering external force. The residual stress adds the stress of external load and impacts on the performance of the structure.This paper uses the electro-chemical corrosion method, and makes some improvement with other researchers'study. Then forms steady ideas from the research of making cutting tools, corrosion liquid, the choosing of protecting material and the craftwork. Respectively measures the straight section of the curved side of 10 equilateral angles with thickness of 3.0mm, 3.5mm, 4.5mm, 5.0mm, obtains the values of vertical residual stress in the cross. According to the characteristics of sheet metal forming, the forming process is divided into bending and molding, uses the theoretical analysis of elastic-plastic to analyze process of bending moment, uses rebound moment effect of the arc beam to analyze the rebound process, residual stress has been formed in the stress superposition of the two processes, theoretical analysis shows that the factors which impact on the longitudinal residual stress are relative bending radius and thickness, the former shows more remarkable impact than the latter; According to simulation with ANSYS and comparison with simulation and test values, the results of simulation and test coincide, and the accuracy of the simulation method is verified; uses this method to simulate six types of angle ,whose thickness are 2mm, 3mm, 4mm, 5mm, 6mm, 8mm and there are five types relative bending radius(2,3,4,5,6) of each thickness, acquires the maximum residual stress of inside and outside vertical surface; analyzes the difference between simulation and theory analysis, acquires the approximate formula, concerning relative bending radius and thickness, to calculate the maximum residual stress of the equilateral angle inside and outside vertical surface.