New Solution for Material Damage Characterization of CFRP Laminate with Filament Winding Structure Using a Hexagonal-Shaped Mandrel

We are in the context of the analysis of carbon fiber reinforced plastics (CFRP) high-pressure vessel (COPV - Composite Overwrapped Pressure Vessel) manufactured by filament winding (FW). Classically, the parameters of material models are identified based on flat laminate coupons with specific predetermined fiber orientations, and based on standards like the ones of ASTM relevant for flat coupons. CFRP manufactured by FW has a unique and complex laminate structure, which presents curvatures and ply interlacements. In practice, it is important to use coupons produced with the final manufacturing process for the parameter identification of the material models; if classical coupons produced by e.g. ply lamination are used, the effect of FW structure cannot be accounted for, and cannot be introduced in the material models. It is therefore essential to develop an approach to create representative flat coupons based on the FW process.

In this study, a new hexagonal-shaped mandrel including flat faces in the cylindrical and dome regions is devised and a procedure for defining and testing representative flat coupons with a FW structure is proposed. The hexagonal-shaped mandrel is called “soccer-ball mandrel”. The FW structure obtained on the flat regions by this method matches well with that on the curved region of actual vessel. In addition, the parameters of a material damage model are identified based on physical tests conducted on flat coupons extracted from the flat faces of the soccer-ball COPV and computation results reproduce he experimental ones well.