Study of anisotropic character induced by microscale laser shock peening on a single crystal aluminum

The beam spot size used in microscale laser shock peening is of the same order as grain size in many materials. Therefore, the deformation is induced in only a few grains so that it is necessary to treat the material as being anisotropic and heterogeneous. In order to investigate the corresponding anisotropic features, different experimental techniques and three-dimensional finite element simulations are employed to characterize and analyze anisotropic responses for single crystal aluminum under single pulse shock peening at individual locations. X-ray microdiffraction techniques based on a synchrotron light source affords micron scale spatial resolution and is used to measure the residual stress spatial distribution along different crystalline directions on the shocked surface. Crystal lattice rotation due to plastic deformation is also measured with electron backscatter diffraction. The result is experimentally quantified and compared with the simulation result obtained from finite element analysis. The influence of crystalline orientation is investigated using single crystal plasticity in finite element analysis. The results of the finite element simulations of a single shock peened indentation are compared with the finite element results for a shocked line of plain strain deformation assumption. The prediction of overall characters of the anisotropic characters associated with microscale laser shock peening will lay the ground work for the practical application of microscale laser shock peening. (c) 2007 American Institute of Physics.