Identification of the four orthotropic plate stiffnesses using a single open-hole tensile test
Résumé
Identification of in-plane orthotropic elastic properties of composite materials usually requires various specimens and tests, such as tensile tests performed in different directions. However, since more 15 years optical full-field measurement methods supply a huge amount of data from one single test and make it possible to identify properties from quite a limited number of specimens and tests. In particular, interesting studies have been carried out to design new specific testing approach introducing controlled heterogeneity to activate every stiffness components [1]. However, the idea to use a classical test, well-known and performed by the mechanical community, remains quite attractive. The open hole specimen, widely used under various mechanical solicitations, appears as a good candidate. Moreover the feasibility to identify orthotropic parameters of one specimen under tension has been shown [2]. The link between the experimental data and the numerical identification process is still complicated and a particular study, focusing on the utilization of the metrological content of experimental data, is necessary. The present contribution introduces a model which includes both optical and signal processing considerations. A complete study proving the 'identifiability' of the orthotropic elastic properties results in the evaluation of the required quality of experimental data. Finally, a first set of results is presented for a new type of NCF-based composite materials.