Laser shock adhesion test numerical optimization for composite bonding assessment
TypeArticles dans des revues avec comité de lecture
The present work presents the latest development of laser shock adhesion test (LASAT) technology, targeting the weak bond detection in bonded aeronautic structures. This problematic is still holding back a wider use of bonding, which could however be a significant breakthrough in the way of assembling parts. By mechanically loading the bondline thanks to laser-induced shock waves, LASAT acts as proof test to reveal the presence of local weaknesses. In the present paper, focus is made on the optimization of the laser shock parameters regarding the assembly to test. Objective is to avoid loading too much the composite, thus avoiding damage, to increase the test performances. Numerical modelling is used, following a specific methodology, to understand the phenomena and identify the key parameters. The basic laser shock configuration was first investigated. Due to the stress distribution, this setting allows one to test a bond whose strength is equal or below 40% of composite inter-laminar strength. The effects of the laser focal spot on the stress distribution are also quantified. A 4 mm diameter shows good performances for the assembly to test. For the first time, three different optimizations are proposed: tunable pulse duration, double pulses on the front face and symmetrical laser shocks. They are first theoretically described. Numerical results then support these configurations’ performances. The double pulse solution makes it possible to test a bond strength equal or inferior to 80% of composite inter-laminar strength, when symmetrical pulses enable to reach 100% thanks to a sharp stress distribution. These results are validated by experimental evidence that is also presented. Finally, the present work offers helpful information for the development and deployment of LASAT for aeronautic bonded structures.
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Development of a laser shock adhesion test for the assessment of weak adhesive bonded CFRP structures EHRHART, Bastien; ECAULT, Romain; TOUCHARD, Fabienne; BOUSTIE, Michel; BERTHE, Laurent; BOCKENHEIMER, Clemens; VALESKE, Bernd (ELSEVIER, 2014)Adhesive bondin,g bas a great poœnlial far future ligbtweight bigb-loaded structures in the a.eronautic industiy. A preœquisite for sucb an application is dtat the bond quality of the adhesive joint can be assessed in a ...
Experimental and numerical investigations of shock and shear wave propagation induced by femtosecond laser irradiation in epoxy resins ECAULT, Romain; BERTHE, Laurent; TOUCHARD, Fabienne; BOUSTIE, Michel; LESCOUTE, Emilien; SOLLIER, Arnaud; VOILLAUME, Hubert (IOP Publishing Ltd, 2015)In this work, original shock experiments are presented. Laser-induced shock and shear wave propagations have been observed in an epoxy resin, in the case of femtosecond laser irradiation. A specific time-resolved shadowgraphy ...
Numerical modeling of laser-induced shock experiments for the development of the adhesion test for bonded composite materials ECAULT, Romain; TOUCHARD, Fabienne; BOUSTIE, Michel; BERTHE, Laurent; DOMINGUEZ, Nicolas (Elsevier, 2016)In this work, laser shock experiments on composite material are modeled. Focus is made on the development of a reliable numerical model to be used for the laser shock wave adhesion test of bonded composites. Technique ...
Observation of the shock wave propagation induced by a high-power laser irradiation into an epoxy material ESCAULT, Romain; BERTHE, Laurent; BOUSTIE, Michel; TOUCHARD, Fabienne; LESCOUTE, Emilien; SOLLIER, Arnaud; MERCIER, Patrick; BERNIER, Jacky (IOP PUBLISHING, 2014)The propagation of laser-induced shock waves in a transparent epoxy sample is investigated by optical shadowgraphy. The shock waves are generated by a focused laser (3 ns pulse duration—1.2 to 3.4TWcm−2) producing pressure ...
ESCAULT, Romain; BOUSTIE, Michel; TOUCHARD, Fabienne; PONS, Frédéric; BERTHE, Laurent; CHOCINSKI-ARNAULT, Laurence; EHRHART, Bastien; BOCKENHEIMER, Clemens (Elsevier, 2013)A laser shock wave technique has been used to study the damage tolerance of T800/M21 CFRP (Carbon Fiber Reinforced Polymer) composite material with different lay_ups. Different levels of damage have been created according ...