Consistent Identification of CFRP Viscoelastic Models from Creep to Dynamic Loadings

Rate-dependent models require creep or mechanical tests at various strain rates in order to be identified and validated. Different geometries coexist for creep and static tests (normative geometry) and for dynamic tests. Therefore, due to geometrical sample considerations, experimental results could be inconsistent for identification or validation procedures, inducing, for example, differences on the shear modulus only due to the change of geometry. The objective of this work is to present an improved sample geometry that allows to obtain consistent mechanical tests results at various strain rates highlighting the rate dependencies of laminates. In particular, a complete mechanical validation of the sample geometry for dynamic tests is successfully performed in order to avoid inconsistency. Results of static and dynamic tests on the validated geometry are analysed, and the rate dependency of the elastic properties of the UD T700GC/M21 mesoscopic ply is highlighted on a wide strain rate range (10-3 to 102s-1). Finally, the identification of a non-linear viscoelastic model is performed on dynamic and creep tests results in order to obtain a representative model for dynamic, static and creep loadings, and to demonstrate the importance of introducing the improved geometry for the dynamic tests.