Résumé
The use of fiber reinforced composites has increased in naval construction due to their favorable physical properties in particular their specific modulus, ease of fabrication and excellent mechanical behavior in the marine environment. As such, sandwich materials, composed of two laminated facings and a polymer foam core, are the first-choice materials for the design of light and rigid superstructures for the vessels. The purpose is to study and model the mechanical behavior of sandwich materials made of recycled and bio-based materials (biopolymers reinforced by low environmental impact fibers) in the nautical construction, since they can offer equivalent specific mechanical properties compared with traditional composites, while having better environmental credentials. In order to establish a homogenized behavior of a sandwich material, the work is divided into two parts: the characterization of the foam and then of the bio-based composite. The first part consists of studying the mechanical behavior of a reference foam of polyvinyl chloride (PVC) and those of recycled polyethylene terephthalate (PETr) substitute foams. The evaluation of the behavior of a foam-model is complicated as a result of the anisotropy induced by the process and the structural heterogeneity at the scale of laboratory tests. Compression and shear tests, instrumented by a Digital Image Correlation method, were conducted on different shapes and dimensions of PVC and PETr foams in order to identify the mechanical parameters and thus, lead to measurements of apparent properties. Following the compression tests, PVC and PETr foams are found to be transversely isotropic. Using these experimental results, the elastic mechanical behavior of PVC and PETr foams is identified based on a finite element model updating method, using Abaqus and Matlab, by minimizing the difference between the simulated modulus, and the experimental apparent elastic one.