Influence Of Laser Shock Processing On Properties Of Cu Composite And Finite Element Simulation

In this paper, laser shock processing was used to shock SiCp/Cu composite and. weld crack restored by electro-spark overlaying which volume fraction of SiCp particle reinforcement is 2.5%, studying the influence of laser shock processing on properties of surface micro-hardness, residual stress, tensile strength of Cu composite.Single point of impact on the test specimen surface, studies show that: laser shock processing could increase the residual compressive stress of surface of Cu composite, residual compressive stress comes up to -64MPa after a single impact, and comes up to -100MPa. after the second impact; Micro-hardness of impact coverage increased by 12.5% compared with the free surface after a single impact, and increased about 12.5% compared with the first shock surface after the double impact, compared with the single impact micro-hardness increased the same width after the twice impact.The impact cover the whole surface of the test specimen, studies show that: tensile strength of material increased by 9.4% and 13.7% after one and twice impact on the one-side surface, but the rupture elongation decreased a little, Watch the SEM morphology of tensile fracture surface of SiCp/Cu composite, where exist dimples and SiCp showed that the tension failure is ductile fracture, and it was proved that crackle emerge from the interface between matrix and particle reinforcement. So the state of matrix of SiCp/Cu is important to the tensile strength of material.Laser shock processing on SiCp/Cu composite weld crack restored by electro-spark overlaying could reduced the tensile residual stress of weld area to some extent, even it could generate compressive residual stress after twice shock, reduce or eliminate the bad influence on weld crack from tensile residual stress, improve the quality of weld crack.Laser shock processing could improve micro-hardness of weld crack and round area, especially for the micro-hardness of fusion zone, and the distribution of micro-hardness of weld crack will be more gently and uniform.Tensile strength of test specimen restored by electro-spark overlaying is lower than original test specimen, but it will better than original test specimen when shocked by laser for one and twice, which show that laser shock processing could improve tensile strength.With the help of the commercial software ANSYS / LS-DYNA, establish a laser shock SiCp/Cu composite unit cell finite element analysis model, model the process of laser shock processing. Simulation results show that: residual compressive stress widely exist on the matrix model, and matrix was yielded and enhancement; laser threshold power density is 6GW/cm~2, With the raise of laser power density, compressive residual stress in matrix model will increase when the laser power density less than the threshold; but when it exceed the threshold, compressive residual stress will reduce with the raise of laser power density, when laser power density comes up to laser threshold power density, the SEQV on contact interface still less than breaking strength of interface; after twice shock, compressive residual stress on model improved obviously, the value increased equals the value increased by the first shock.