Laser-induced shockwaves for damage assessment and characterization at high strain rates in the fiber direction of unidirectional composites

Abstract

Composite materials are of paramount interest in the aerospace industry. To evaluate their survivability when subjected to high-strain rate loading, laser-generated shockwaves are employed. Back-face velocities are analyzed for the characterization of shockwave propagation in the fiber direction of unidirectional carbon-fiber composites, and back-face microscopic inspection is used for damage observation. Challenges such as reflective surface requirements and limited sample thickness were addressed by gold-coating the back face and using thin bonded composite stripes. Experimental investigations revealed a linear relationship between back-face velocity and density of power and provided in-plane characteristics at high-strain rate regimes: microscopic inspections unveiled flexural cracks and microcracks in the matrix; speed of sound evaluation provided comparable values to ultrasonic measurements on similar composites.