Originally, the use of laser-induced shock waves on metals to achieve property or functional benefits was referred to as laser shock processing, a broader, more inclusive term. As it happened, laser peening was the first commercial aspect of laser shock processing. However, laser-induced shock waves have found uses in other industrial applications outside of surface enhancement technologies.
One application is for metal shaping or forming. By selectively laser shocking areas on the surface of metal sheets or plates, or smaller items such as airfoils, the associated compressive residual stresses cause the material to flex in a controllable manner. In this way a particular shape can be imparted to a component, or a distorted component might be brought back into the desired shape. Thus, this process is capable of bringing manufactured parts back into design tolerance limits and form shaping thin section parts.
Another variation is to use the shock wave for spallation testing of materials. This application is based on the behavior of shockwaves to reflect from the rear free surface of a work piece as a tensile wave. Depending on the material properties and the shock wave characteristics, the reflected tensile wave may be strong enough to form microcracks or voids near the back surface, or actually "blow-off" or spall material from the back surface. This approach has some value for testing ballistic materials.
Use of laser shocks to measure the bond strength of coatings on metals has been developed over a period of years in France called LASAT for Laser Adhesion Test. This application is also based on the behavior of shockwaves to reflect from the rear free surface of a work piece as a tensile wave. If the back surface is coated with an adherent coating, the tensile wave can be tailored to fracture the bond upon reflection from the surface. By controlling the characteristics of the shock wave, the bond strength of the coating can be measured, or alternatively, determined in a comparative sense.
Careful tailoring of the shockwave shape and intensity has also enabled the inspection of bonded composite structures via laser shocking. The technology, termed Laser Bond Inspection initiates a shockwave that reflects off the backside of a bonded structure and returns as a tensile wave. As the tensile wave passes back through the adhesive bond, depending on the strength of the bond and the peak tensile stress of the stress wave, the tensile wave will either pass through the bond or rupture it. By controlling the pressure of the tensile wave this procedure is capable of reliably locally testing adhesion strength between bonded joints. This technology is most often found in application to bonded fiber composite material structures but has also been shown to be successful in evaluating bonds between metal-composite material. Fundamental issues are also studied to characterize and quantify the effect of shock wave produced by laser inside these complex materials.