Study of damage phenomena induced by edge effects into materials under laser driven shocks

Abstract

Spallation of materials induced by laser driven shock waves is generally produced under uniaxial (one-dimensional (1D)) deformation by irradiating a spot of diameter much greater than the sample thickness. Here, two-dimensional (2D) effects are introduced in shock wave propagation by drastically reducing the loaded spot. Experiments performed on aluminium samples detect the effect of lateral wave propagation, both on recovered samples and on time-resolved VISAR measurements. Damage zones are localized completely differently from that under uniaxial condition, according to the presence of 2D effects, and the signature of these 2D effects can be read on VISAR signals. Numerical simulations provide a full understanding of wave propagation and resulting damage in 1D or 2D configuration. Comparisons with experimental VISAR signals show the possibility of validating more accurately the dynamic damage criteria, including the 2D effects.

Study of the response of CFRP composite laminates to a laser-induced shock

“…Since the spot diameter is 4.2 times larger than the samples thickness, the waves propagation is considered normal to the plies and the shock front is not altered by the edge effects [32]. A delamination threshold has been probed for an incident intensity of [0.9-1.03] GW cm…”

“…This shows that the tensile strength of the interply is lower than the ply one, especially as the interply is subjected to a slightly lower tensile stress. The delamination is spread over a smaller area than the laser spot due to the lateral attenuation of the stress waves [32]. The damage is not continuous within the interply layer and the plies remain stacked, this could be considered as a first stage of damage.…”

Laser Shock Adhesion Test (LASAT) of Electron Beam Physical Vapor Deposited Thermal Barrier Coatings (EB-PVD TBCs)

“…Two-dimensional stress waves are given in Fig.5. The edge effects of shock wave, lateral and non-straight propagation are exhibited and were already described by Boustie et al [9][10]. Upon high shock, a principal shock wave (A region), one-dimensional, is induced on the normal direction of the surface.…”

Cold-Spraying Coupled to Nano-Pulsed Nd-YaG Laser Surface Pre-treatment

“…LASAT was used to measure the adhesion of the coatings and has been described in detail in previous articles (Ref [37][38][39][40][41][42][43][44][45][46]. Basically, LASAT consists in irradiating the rear surface of a substrate with a laser to generate a shock wave.…”