Similitude Law Evaluation For Composite Structures Using Optical Techniques
Free (open access)
L. Ball`ere, P. Viot, L. Guillaumat & J.-L. Lataillade
The aim of this paper is to contribute to similitude law development applied to composite structures. These laws permit one 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...), an optical device such as a high-speedCCD camera, associated with optical techniques for the monitoring of markers, was used. These techniques make it possible to compare displacement lines corresponding to each scale. It is shown that existing similitude laws, used for elastic materials, do not allow one to simulate the behavior of the real scale when this one is damaged. Keywords: optical measurement, similitude laws, impact, composite materials. 1 Introduction For several years, composite materials have played a significant part in the realization of structures used for transportation (aeronautical, nautical, automotive...). During manufacturing or storing of such structures, they can be damaged locally by tool drops without there being any visible deterioration. That is why designers have to appreciate the criticality of such damages to check that this kind of accident is not harmful for the structure during its life. Nevertheless, tests are often very expensive and difficult to set up, especially when the structures’ dimensions are large (fuselages of aircraft, ship hulls, etc.). An alternative way then is to employ small-scale models. The use of these reduced scale structures calls for the identifi- cation of similitude techniques allowing the behavior extrapolation fromthe model to the real scale.
optical measurement, similitude laws, impact, composite materials.