https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Sun, 14 Jun 2026 10:23:22 GMT 2026-06-14T10:23:22Z http://hdl.handle.net/10985/7363 Réponse à l'impact de plaques composites épaisses préchargées en tension uniaxiale. GUILLAUD, Nicolas; FROUSTEY, Catherine; LATAILLADE, Jean-Luc; VIOT, Philippe; DAU, Frédéric This study concerns Carbon / epoxy composite plates. Three di erent thickness were investigated ([0°=45°=90°=45°]i)S for i = 2, 3 or 4 (5, 10 and 15mm thick). An instrumented falling-weight-impact test machine was used for test in this work. Impact energies were 30 J to 214 J. Tensile preloadings were de ned according to the ultimate tensile strength of the plates (300 to 3000 micro strain). Tests were de ned using Doelhert design of experiments for which parameters were thickness, tensile preloading and impact energy and were performed on a drop tower. Impact behavior were characterized from impact force and displacement measurements. The strain state of back sheet was determined using digital correlation. Damage was characterized using non destructive control technique and deply technique.Post impact tension are carried to characterize the residual strength and to see the dammage evolution. Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10985/7363 2013-01-01T00:00:00Z GUILLAUD, Nicolas FROUSTEY, Catherine LATAILLADE, Jean-Luc VIOT, Philippe DAU, Frédéric This study concerns Carbon / epoxy composite plates. Three di erent thickness were investigated ([0°=45°=90°=45°]i)S for i = 2, 3 or 4 (5, 10 and 15mm thick). An instrumented falling-weight-impact test machine was used for test in this work. Impact energies were 30 J to 214 J. Tensile preloadings were de ned according to the ultimate tensile strength of the plates (300 to 3000 micro strain). Tests were de ned using Doelhert design of experiments for which parameters were thickness, tensile preloading and impact energy and were performed on a drop tower. Impact behavior were characterized from impact force and displacement measurements. The strain state of back sheet was determined using digital correlation. Damage was characterized using non destructive control technique and deply technique.Post impact tension are carried to characterize the residual strength and to see the dammage evolution. http://hdl.handle.net/10985/7385 Damage tolerance of impacted curved panels BALLERE, Ludovic; LATAILLADE, Jean-Luc; CLOUTET, S; GUILLAUMAT, Laurent; VIOT, Philippe The final aim of this study is to evaluate the influence of impact damage on the residual strength of carbon/epoxy vessels stressed by internal pressure. An intermediate stage determined the residual behaviour of pre-impacted curved panels loaded in tension. Curved panels were impacted, reproducing the damage types observed in impacted vessels filled with propellant. Delamination damage was assessed by ultrasonics and optical microscopy used to observe intra-laminar mechanisms. Tension after impact (TAI) tests quantified the residual behaviour. An experimental design was used as an alternative to the complex analytical modelling of dynamic damage mechanisms. With this original technique, empirical relationships were established, linking impact parameters to residual properties. The force to failure was found to vary in a bi-linear manner with impact energy. Below a specific level of impact energy corresponding to failure in 4/7 of the plies, there is no significant reduction in the residual strength. The composite Young’s modulus decreased linearly with impact energy. Tue, 01 Jan 2008 00:00:00 GMT http://hdl.handle.net/10985/7385 2008-01-01T00:00:00Z BALLERE, Ludovic LATAILLADE, Jean-Luc CLOUTET, S GUILLAUMAT, Laurent VIOT, Philippe The final aim of this study is to evaluate the influence of impact damage on the residual strength of carbon/epoxy vessels stressed by internal pressure. An intermediate stage determined the residual behaviour of pre-impacted curved panels loaded in tension. Curved panels were impacted, reproducing the damage types observed in impacted vessels filled with propellant. Delamination damage was assessed by ultrasonics and optical microscopy used to observe intra-laminar mechanisms. Tension after impact (TAI) tests quantified the residual behaviour. An experimental design was used as an alternative to the complex analytical modelling of dynamic damage mechanisms. With this original technique, empirical relationships were established, linking impact parameters to residual properties. The force to failure was found to vary in a bi-linear manner with impact energy. Below a specific level of impact energy corresponding to failure in 4/7 of the plies, there is no significant reduction in the residual strength. The composite Young’s modulus decreased linearly with impact energy. http://hdl.handle.net/10985/7384 Polypropylene foam behaviour under dynamic loadings: Strain rate, density and microstructure effects BOUIX, Rémy; LATAILLADE, Jean-Luc; VIOT, Philippe Expanded polypropylene foams (EPP) can be used to absorb shock energy. The performance of these foams has to be studied as a function of several parameters such as density, microstructure and also the strain rate imposed during dynamic loading. The compressive stress–strain behaviour of these foams has been investigated over a wide range of engineering strain rates from 0.01 to 1500 s 1 in order to demonstrate the effects of foam density and strain rate on the initial collapse stress and the hardening modulus in the post-yield plateau region. A flywheel apparatus has been used for intermediate strain rates of about 200 s 1 and higher strain rate compression tests were performed using a viscoelastic Split Hopkinson Pressure Bar apparatus (SHPB), with nylon bars, at strain rates around 1500 s 1 EPP foams of various densities from 34 to 150 kgm 3 were considered and microstructural aspects were examined using two particular foams. Finally, in order to assess the contribution of the gas trapped in the closed cells of the foams, compression tests in a fluid chamber at quasi-static and dynamic loading velocities were performed. Thu, 01 Jan 2009 00:00:00 GMT http://hdl.handle.net/10985/7384 2009-01-01T00:00:00Z BOUIX, Rémy LATAILLADE, Jean-Luc VIOT, Philippe Expanded polypropylene foams (EPP) can be used to absorb shock energy. The performance of these foams has to be studied as a function of several parameters such as density, microstructure and also the strain rate imposed during dynamic loading. The compressive stress–strain behaviour of these foams has been investigated over a wide range of engineering strain rates from 0.01 to 1500 s 1 in order to demonstrate the effects of foam density and strain rate on the initial collapse stress and the hardening modulus in the post-yield plateau region. A flywheel apparatus has been used for intermediate strain rates of about 200 s 1 and higher strain rate compression tests were performed using a viscoelastic Split Hopkinson Pressure Bar apparatus (SHPB), with nylon bars, at strain rates around 1500 s 1 EPP foams of various densities from 34 to 150 kgm 3 were considered and microstructural aspects were examined using two particular foams. Finally, in order to assess the contribution of the gas trapped in the closed cells of the foams, compression tests in a fluid chamber at quasi-static and dynamic loading velocities were performed. http://hdl.handle.net/10985/8294 Scale effects on the response of composite structures under impact loading BALLERE, Ludovic; LATAILLADE, Jean-Luc; GUILLAUMAT, Laurent; VIOT, Philippe For several years, composite materials have taken a significant part in the realization of structures designed for transport (aeronautical, nautical, automotive. . .). In order to qualify the behavior of such structures, preliminary validation tests have to be done. These specific tests are often very expensive and difficult to set up, especially when the structure dimensions are large (fuselages of aircraft, ship hulls. . .). An alternative way is then to employ small-scale models. The use of these reduced scale structures requires the identification of similitude models allowing the extrapolation of the small-scale model behavior to the real structure. Although largely developed in the case of homogeneous materials, such similitude techniques are not clearly identified for composite materials taking into account the damage evolution during an impact. The purpose of this article is firstly to present existing similitude techniques making it possible to predict the composite structure behaviour from the knowledge of small-scale model response. Secondly, experiments were done on two scale of samples carried out by stratification of unidirectional carbon/epoxy plies. These results were finally compared with the analytical predictions of similitude laws currently used. The aim of this paper is to contribute to similitude laws development applied to composite structures. These laws permit to extrapolate the small-scale model behavior to the real scale one. Existing approaches have been established following two different methods. They are summarized in this paper and applied to impact loadings on two laminated plate scales. In order to complete data collected by ‘‘conventional’’ instrumentation (force transducer, displacement sensor, accelerometer.. .), optical device such as an high-velocity CCD camera, associated with optical techniques for the monitoring of markers, were used. These techniques make possible to compare displacement lines corresponding to each scale. It is shown that existing similitude laws, used for elastic materials, do not allow to simulate the behavior of the real scale when this one is damaged. Tue, 01 Jan 2008 00:00:00 GMT http://hdl.handle.net/10985/8294 2008-01-01T00:00:00Z BALLERE, Ludovic LATAILLADE, Jean-Luc GUILLAUMAT, Laurent VIOT, Philippe For several years, composite materials have taken a significant part in the realization of structures designed for transport (aeronautical, nautical, automotive. . .). In order to qualify the behavior of such structures, preliminary validation tests have to be done. These specific tests are often very expensive and difficult to set up, especially when the structure dimensions are large (fuselages of aircraft, ship hulls. . .). An alternative way is then to employ small-scale models. The use of these reduced scale structures requires the identification of similitude models allowing the extrapolation of the small-scale model behavior to the real structure. Although largely developed in the case of homogeneous materials, such similitude techniques are not clearly identified for composite materials taking into account the damage evolution during an impact. The purpose of this article is firstly to present existing similitude techniques making it possible to predict the composite structure behaviour from the knowledge of small-scale model response. Secondly, experiments were done on two scale of samples carried out by stratification of unidirectional carbon/epoxy plies. These results were finally compared with the analytical predictions of similitude laws currently used. The aim of this paper is to contribute to similitude laws development applied to composite structures. These laws permit to extrapolate the small-scale model behavior to the real scale one. Existing approaches have been established following two different methods. They are summarized in this paper and applied to impact loadings on two laminated plate scales. In order to complete data collected by ‘‘conventional’’ instrumentation (force transducer, displacement sensor, accelerometer.. .), optical device such as an high-velocity CCD camera, associated with optical techniques for the monitoring of markers, were used. These techniques make possible to compare displacement lines corresponding to each scale. It is shown that existing similitude laws, used for elastic materials, do not allow to simulate the behavior of the real scale when this one is damaged. http://hdl.handle.net/10985/7386 The influence of acrylate triblock copolymer embedded in matrix on composite structures’ responses to low-velocity impacts DENNEULIN, Sébastien; LEONARDI, Frédéric; LATAILLADE, Jean-Luc; VIOT, Philippe In passive safety structures the use of composite materials has increased significantly recently due to their low specific mass and high energy absorption capacities. The purpose of this experimental study is to describe the macroscopic behaviors of different Kevlar woven composite materials with different kinds of matrix (pure and with acrylate based block copolymer additives: Nanostrength ) under lowvelocity impact. Tests were performed with a drop weight tower on square plates (100 100 mm2) clamped by means of a circular fixture. Images were recorded during impact by a high-speed video camera fixed underneath the plate. It was found that Kevlar epoxy composite material with Nanostrength M52N has the best resistance to perforation. The second purpose is to study the influence of physicochemical parameters (fibers ratio, percentage of M52N, micro-porosity) on the behavior of the selected composite material. Based on correlation between pictures, displacement, and loading histories, two criteria are defined to quantify the energy absorption capability of the composite material just before the fibers’ failure and after perforation of the plate. A high-fiber weight improves performance regarding criteria and also improves the efficiency of the block copolymer present in the epoxy matrix. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10985/7386 2012-01-01T00:00:00Z DENNEULIN, Sébastien LEONARDI, Frédéric LATAILLADE, Jean-Luc VIOT, Philippe In passive safety structures the use of composite materials has increased significantly recently due to their low specific mass and high energy absorption capacities. The purpose of this experimental study is to describe the macroscopic behaviors of different Kevlar woven composite materials with different kinds of matrix (pure and with acrylate based block copolymer additives: Nanostrength ) under lowvelocity impact. Tests were performed with a drop weight tower on square plates (100 100 mm2) clamped by means of a circular fixture. Images were recorded during impact by a high-speed video camera fixed underneath the plate. It was found that Kevlar epoxy composite material with Nanostrength M52N has the best resistance to perforation. The second purpose is to study the influence of physicochemical parameters (fibers ratio, percentage of M52N, micro-porosity) on the behavior of the selected composite material. Based on correlation between pictures, displacement, and loading histories, two criteria are defined to quantify the energy absorption capability of the composite material just before the fibers’ failure and after perforation of the plate. A high-fiber weight improves performance regarding criteria and also improves the efficiency of the block copolymer present in the epoxy matrix.