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Saint-Sauveur-en-Rue, France

Budzik M.K.,University of Aarhus | Budzik M.K.,University Bordeaux I2M | Budzik M.K.,French National Center for Scientific Research | Budzik M.K.,Arts et Metiers ParisTech | And 6 more authors.
Applied Physics A: Materials Science and Processing | Year: 2014

The aim of this paper is to investigate the mesoscale behavior and structure of an adhesive near the fracture front of an asymmetric joint consisting of carbon fiber/epoxy resin composites bonded with a relatively soft, epoxy adhesive. A single cantilever beam fracture test at constant separation rate gave steady-state crack propagation, details of which were followed by digital image correlation (DIC). A deformed, triple line region was found between the adhesive, air, and the composite, somewhat resembling a "wetting ridge," as found with a liquid meniscus in contact with a soft solid. Importantly, the partially separated bondline layer took part in (non-unidirectional) load transfer between adherends (and thus energy dissipation), contrary to common assumptions where the separated bondline is assumed no longer to play a structural role. A simple model, based on the Flamant contact mechanics approach, is proposed and compared with both a finite element solution and experimental data extracted from image correlation. The model points out the importance of two length scales: process zone extent and adhesive thickness, both being known to affect global properties of bonded structures. © 2013 Springer-Verlag Berlin Heidelberg. Source


Leleux A.,University Bordeaux I2M | Leleux A.,French National Center for Scientific Research | Leleux A.,Arts et Metiers ParisTech | Micheau P.,Universite de Sherbrooke | And 3 more authors.
Journal of Nondestructive Evaluation | Year: 2013

This article presents a technique for the generation and detection of Lamb waves guided along large plate-like structures made from various types of materials (metal, polymer, fibre-reinforced composite, etc.). A multi-element matrix ultrasonic probe is driven using the well-known phased array principle, for launching and detecting pure Lamb modes in/from specific directions along the plate, which are arbitrary for isotropic materials and limited to specific directions for anisotropic materials, e.g. principal directions or directions for which both phase and group velocities are collinear. The probe is gel-coupled to the tested specimen and allows quick inspection of large area from its fixed position, even of zones with limited access. The technique, which takes into account the frequency dispersive effects, is different than SHM-like (Structural Health Monitoring) inspection, since all transmitting or receiving elements are grouped together in a localized area defined by the active surface of the probe, and not permanently attached to the tested structure. The use of a multi-element probe, for long range Lamb waves-based inspection, is also distinctive from that usually performed, which consists of very local inspection of a material by steering the ultrasonic beam below and nearby the probe. A prototype is presented, as well as measurements of its performances in terms of modal selectivity and directivity. Finally the detection and localisation of a through-thickness hole in a large aluminium plate, of a delamination-like defect in a carbon epoxy composite plate and of an impact damage on a stiffened composite curved plate are shown. © 2013 Springer Science+Business Media New York. Source


Tirand G.,University Bordeaux I2M | Tirand G.,ASTF Aerospace Service Tolerie Fine Groupe ALCEN | Arvieu C.,University Bordeaux I2M | Lacoste E.,University Bordeaux I2M | Quenisset J.-M.,University Bordeaux I2M
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

The need to reach the mechanical performance of age hardened Al-Mg-Si (6000 series) base alloy of structures, the assemblies of which are processed by laser welding, has required the efficiency evaluation of age hardening heat treatment performed after welding. It has been established that post-laser aging treatments are not efficient enough to give laser welded assemblies the expected performance of hardened Al base alloy in term of micro-hardness, ultimate tensile strength, and failure deformation. This lack of efficiency has been attributed to insufficient cooling kinetic during laser welding rather than to composition deviation of the bead due to the use of Si rich filler. The interposition of solution heat treatment between welding and aging treatment has been proposed and has shown its efficiency to give the laser welded zone a sufficient strength, similar to that of Al base alloy. © 2013 The Minerals, Metals & Materials Society and ASM International. Source


Budzik M.K.,University Bordeaux I2M | Budzik M.K.,French National Center for Scientific Research | Budzik M.K.,Arts et Metiers ParisTech | Budzik M.K.,Technical University of Gdansk | And 6 more authors.
Soft Matter | Year: 2012

The effects of variability of intrinsic adhesion within a joint have been studied using a single cantilever beam (SCB) test. Fracture energy was found not to be a simple function of relative areas of 2 surface pre-treatments: a 'weak' zone decreased strength more than expected from simple, additive considerations. By severing the adhesive along the strong-weak transition, fracture energy increased. The prior antagonist effect appears to be directly linked to supplementary stresses generated near the crossover by continuity of the adhesive layer, existent despite differences in adhesion. © 2012 2012 The Royal Society of Chemistry. Source

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