Virtual calculation of the B-value allowables of notched composite laminates

Abstract

The design of composite structures relies on the accurate determination of design allowables, which are statistically based material parameters that take into account manufacturing, geometrical and microstructure variability. The accurate determination of these design parameters requires extensive experimental testing, which makes the certification process of a composite material extremely costly and time consuming. To increase the efficiency of the design process, there is the need to develop alternatives to the mostly experimental material characterization process, ideally based on accurate and quick modelling analysis combined with powerful statistical tools.In this work an analytical model to compute the notched strength of composite structures based on three ply-based material properties (elastic modulus, unnotched strength and R-curve) is combined with an uncertainty quantification and management (UQ&M) framework to compute the B-basis design allowables of notched configurations of CFRP laminates. The framework is validated with open-hole tension experimental results for the IM7/8552 material. Given the analytical nature of the developed framework and consequent computational efficiency, the UQ&M methodology is applied to the generation of design charts for notched geometries, whose generation would otherwise be impractical, using experimental test based methods.