Measurement of dynamic characteristics of metal sheet under laser shock

Abstract

A new approach is developed to measure the dynamic characteristics of metal sheet under laser shock, including deformation velocity, strain, and strain rate. The detecting laser beam is partially shaded by the target deformation induced by the laser action. A photodiode transforms the received beam intensity real time into an electrical signal which could record the process of the target deformation. The functional relation between the electrical signal and the deformation of the metal sheet is derived. The deformation curve of a thin aluminum and the velocity curve of its deformation are also obtained during the experiment. The results indicate that the average velocity of the elastic deformation of the target can reach 2.999×10 3 m/s in the central area. This new method provides an approach in the study of the effect of strain rate on deformation.OCIS codes: 320. 7100, 350.4600, 140.3580, 120.1880, 120.7250. doi: 10.3788/COL201210.043201. Laser shock forming (LSF) of metal sheets is a new and competitive laser-based manufacturing technology [1] . When a high-power, short-pulse laser acts on a metal surface, plasma with high temperature and pressure is produced in a very short time because of laser energy absorption. Under the restraint layer, the plasma expands and explodes, resulting in a strong shock wave that propagates in the metal. The foregoing is a dynamic response process with high strain rate, so it changes the microstructure and mechanical properties of the metal [2−4]

Measurement of the average strain rate of thin aluminum deformation under laser shock

“…10, the functional relationship between the voltage U on the oscilloscope and the deformation d 1 of the metal sheet at the center of the target is shown as the following equation: 10, the functional relationship between the voltage U on the oscilloscope and the deformation d 1 of the metal sheet at the center of the target is shown as the following equation: …”

Study of Laser Peening on TiAl Alloy Properties with Different Parameters

“…Laser peening can tremendously eliminate the harmful tensile stress of work-piece introduced by machining, heat treatment, welding [1] , and improve the surface strength, corrosion resistance and fatigue life of the metal work-piece [2] . Laser peening also can precisely control the distribution and the depth of residual stress field [3] , the degree of reinforcement [4] , and fatigue performance [5] .…”