Study Of The Relationship Between Residual Stress And Pile-up By Impact Indentation

In this paper, we study a method measuring residual stress by using micro-damage impacting. This method intend to study the inner relationship between the indentation around impact position, or called pileup and residual stress, expecting to get the magnitude of the residual stress, and judging direction from the size of the residual stress.First of all, with the use of finite element model on impact indentation established by Abaqus software, we carried out simulation to the specimen with different residual stresses. Through a large amount of calculation, we get the basic relations between residual stress and the amount of indentation surrounding pileup, which provided an important reference for the subsequent experimental study.In order to carry out impact experiments on specimen, we designed and manufactured experiment platform with the function of preloading, which can be ancillary used with impact indentation instrument. Two different methods of non-contact measuring to the deformation of compaction indentation were adopted in this paper. The first one is a kind of laser displacement sensor based on triangle method, measuring the indentation surface deformation by point scanning with the combination of sensor and 2-d platform. In order to further confirm the accuracy of the measurement result in last step, we also adopted nano-precision confocal microscope to full impact indentation deformation measurement, and the result of the two different methods get good consistency.Through the series experiment and finite simulation we find that, there have internal relations between pileup and residual stress' size and direction under different uniaxial residual stress, which is the tensile residual stress decreases the size of pileup, while the compression residual stress increases the size of pileup.