Analysis of the Application of a Nanosecond Laser Pulse for Dynamic Hardness Tests Under Ultra-High Strain Rates

Abstract

Experimental and numerical tests of surface plastic deformation generated under different strain rates were performed. Deformations were introduced by both classical Brinell and laser pulse hardness tests. An Nd:YAG laser with a wavelength of 1064 nm and a laser pulse time length of 10 ns was used to generated a shock wave to induce local plastic deformation on the material surface. The laser pulse induces a repeatable plastic deformation of a surface without thermal effects on the surfaces. Based on imprint geometry, the dynamic hardness of materials was evaluated at a strain rate of the order 107 s-1. Numerical analyses carried out included quasi-static and dynamic Brinell hardness tests and laser pulse interactions with materials. The Rusinek-Klepaczko constitutive model applied in the calculations allows the prediction of the mechanical characteristics at a strain range strain range from 10 to 4 s-1 to 107 s-1. Numerical and experimental results from the surface plastic deformations show close agreement.