Identification de lois de comportement élastique et viscoélastique par mesure de champs

Abstract

Rigorous determination of elastic and viscoelastic mechanical characteristics is necessary for reducing the safety factors used for technical applications of panels. Usual investigations to identify elastic and viscoelastic materials rely on statically determined tests as bending, tension, compression or shear. In these tests, the stress is known at the location of measurement points, and determined only by the boundary conditions. Price of simplicity is that one can only find one component of the viscoelastic stiffness matrix. New methods, based on inverse problem solving, allow the determination of several components by one test only. In these tests, the stresses field depends on the boundary conditions, but also on the constitutive equations. Through this dependance, it is possible to increase the number of measurements and access these components. It is necessary to optimise the tests in order to activate these components. These methods will be described. In order to verify the pertinence of this approach, preliminary results were obtained by simulated elastic identifications. The results quality depends on the optimization of tests. Finally, several tests are made, using plywood panels, to validate this new approach.