Physical approach to adhesion testing using laser-driven shock waves

Abstract

This paper deals with an adhesion test of coatings using laser-driven shock waves. Physical aspects concerning laser–matter interaction, shock wave propagation and interface fracture strength are described. This comprehensive approach using two numerical codes (HUGO and SHYLAC) allows the determination of mechanisms responsible for coating debonding and a quantitative evaluation of fracture strength. From this description, a coating test protocol is also designed. To diagnose coating debonding, it is based on the analysis of experimental rear free surface velocity profiles measured by velocity interferometer system for any reflectors (VISAR). Ni electrolytic coating (70–90 µm) deposited on a Cu substrate (120–190 µm) is used for the experimental validation of the test. The fracture strength is 1.49 ± 0.01 GPa for a laser pulse duration of 10 ns at 1.064 µm.

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

“…It concerns thin coatings [3][4][5], and bonded assemblies [6,7]. The potential disbond is detected using the non-intrusive measurement of the free surface velocity [8,9] or ultrasonic C-scan [10].…”

A New Diagnosing Method of the Internal Structure of the Titanium Fan of a Jet Engine with Laser Ultrasonics

“…High power pulsed laser interaction with matter yields to very high amplitude pressure loading with a very short duration, and produces a strong short shock wave into the solid substance [15][16][17]. When a laser pulse of short duration and high density of power is focused on the surface of a solid target, the laser energy absorption of the target surface generates plasma, whose expansion induces a shock wave.…”

Use of the Hugoniot elastic limit in laser shockwave experiments to relate velocity measurements

“…The intensity of the stress wave in the body of the plate is related to the material velocity behind it by p s u U 0 (13) where Us is the velocity of the stress wave and up is the induced particle velocity. At the free surface of the plate where the material velocity may be measured, the interaction of the positive incident wave and negative reflected wave has the effect of cancelling the surface stress (stress at a free surface is always 0), and doubling the material velocity.…”

“…In the Laser Shockwave Technique (LST), initially developed for determining adhesion of thin films and coatings to substrates [8][9][10][11][12][13][14][15][16][17], a high-energy pulsed laser generates a compressive shock wave at the upper surface of a test sample. The compressive shock traverses the specimen.…”