Shock adhesion test for composite bonded assembly using a high pulsed power generator

In a context of the rising use of composite assemblies in aeronautic or defense fields, the assessment of their strength is a key issue. The method developed in this study attempts to provide solutions. A shock adhesion test based on short compressive loads, obtained by a high pulsed power generator, is proposed as a proof test to ensure the quality of composite bonded assemblies. A calibrated load induces a local tensile stress able to damage the bond interface. The high pulsed power source is the GEnerateur de Pression Isentropique device (Isentropic Pressure Generator), used to generate the required stresses, with a 450 ns pulse duration to test assemblies above the mm thickness range. The understanding of the mechanisms of wave propagation and tensile stress generation within these multilayer assemblies are scientific challenges. The ability of the technique to induce a tensile stress able to disbond the laminates and the assemblies is demonstrated. This paper details the response of carbon epoxy laminates and their bonded assemblies to a shock loading near the damage threshold

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

Laser-induced shock yields to a local tensile stress within a sample. This high strain rate stress can be used to verify the bond strength between two layers. This method has been applied to Carbon Fibre Reinforced Polymer (CFRP) composite laminates, involved in aeronautic or defense industry. Experiments have been carried out on high power laser facility in the nanosecond regime. A velocimetry interferometer has been used to record the material velocity at the back surface of the samples. This study provides a comprehensive approach of the response of CFRP laminates of different thicknesses to a shock load normal to the fibres direction. The stress waves generation and propagation within the laminate and the induced delamination are key issues of this work. The main result is the ability of the technique to evaluate the out-of-plane strength of these laminate

Advancements in Design and Analysis of Protective Structures 2019

This ADAP 2019 Annual Issue follows and extends the ADAP Special Volume of 2018 and aims at providing a further insight into current trends and recent advancements in design and analysis, experimental testing, and modelling of protective structures

INCAS BULLETIN, Volume 15, Issue 3/ 2023, pp. 31 – 46 (P) ISSN 2066-8201, (E) ISSN 2247-4528 Off-axis response and shear characterization of unidirectional ply-level hybrid carbon-fiber-reinforced polymer materials

Composite materials, among them Carbon Fiber Reinforced Polymers (CFRP), have become a key material in structural applications for lightweight structures such as spacecraft and aircraft. CFRP can be found under various quality grades and their mechanical performances increase with their cost and quality grade. In order to limit the costs of the material without degrading technical performances, hybridization could be of interest. However, assessing the conservation of quality standards of hybridized CFRP is crucial. This paper investigates the off-axis mechanical response of ply-level hybrid carbon composites, with varying thickness and material quality. Two types of carbon fiber prepregs were combined in the same laminate using symmetric and asymmetric stacking sequences. Monotonic quasi-static off-axis tests were performed to evaluate the non-linear stress-strain behavior of the laminates, with Digital Image Correlation used to measure strain. The apparent elastic modulus and the in-plane shear modulus were evaluated from the tensile tests at three off-axis angles. The results indicate that the hybrid laminates exhibit higher failure stress levels compared to simple laminates, with an intermediate failure strain. Overall, this study provides insights into the off-axis mechanical behavior of ply-level hybrid carbon fiber composites, with potential applications in the design of composite structures

Effects of the shock duration on the response of CFRP composite laminates

Shock loads induce a local tensile stress within a sample. The location and amplitude of this high strain rate stress can be monitored respectively by the duration and intensity of the shock. The process is applied to carbon fibre reinforced polymer (CFRP) composites, involved in aeronautic or defense industry. This paper describes the response of CFRP laminates of different thicknesses to a shock load normal to the fibres direction. The effects of the shock duration on the wave propagation are key issues of this work. Experiments have been performed on high power laser facilities and on a high power pulsed generator to get a wide range of pulse duration from fs to µs. Numerical simulation provides a comprehensive approach of the wave propagation and tensile stress generation within these complex materials. The main result concerns the relation between the load duration, the tensile stress and the induced delamination within 1, 4 and 8 ply composite laminate

Étude expérimentale de l’endommagement de composites sous choc LASER

Dans un contexte de mise en œuvre croissante des composites dans les secteurs aéronautiques et de la défense, la compréhension de leur comportement sous choc et de l’endommagement induit est un point crucial développé dans cette étude. Des LASER impulsionnels intenses sont mis en œuvre pour la génération d’impacts localisés et calibrés sur ces matériaux complexes, supportés par de nombreux diagnostics en temps réel et post-choc pour l’étude et la quantification de l’endommagement dynamique

LAser Shock Adhesion Test (LASAT), an innovation dedicated to industry

NonWOSAvailable online for free at http://www.ila.org.in/kiran/kiran_19_2.pdfInternational audienc

State-of-the-art laser adhesion test (LASAT)

This paper proposes a state-of-the-art laser adhesion test. It consists of testing material interfaces with laser-driven shock wave. Since the first demonstration in the 1980s by Vossen, many studies and developments have been done. This paper presents recent experiments and developments on the basic physics involved. Results show the ability of the technique to perform a quantitative adhesion test for a wide range of materials and configurations. Edge effect principle and ultra-short shock wave give perspectives for new applications for multi-layer combination of material. Fundamental principles are evidenced through experiments on bulk ductile materials before demonstrating their application to coated systems

The Use of Laser-Doppler Interferometry Based on a Fabry-Perot Etalon for Shock Adhesion Test Applied to Adhesively Bonded Materials

Peer reviewed: YesNRC publication: Ye

Adhesive Bond Testing By Laser Induced Shock Waves

Peer reviewed: YesNRC publication: Ye