The usage of fibre-reinforced composites in automotive body structures is still a rarity. The main goal in body structure development is to design lightweight structures as cost-efficient as possible. This research contributes to the approach of maximal material usage by considering the strength increase of a carbon-epoxy laminate with increasing strain rate. The objective was to substantiate the well-known material characteristic's strain rate dependency from a coupon level to realistic body structure component – experimentally and numerically. Hence, a special compression fixture was developed to obtain all necessary characteristic values of the investigated T700S DT120 prepreg system. The rectangular coupon specimens were loaded with quasi-static to intermediate strain rates (2×10^-4 to 70s^-1). A second compression fixture was developed to axial load omega cross-sectional specimens with strain rates from 2×10^-4 to 5s^-1. The experimental tests showed a significant increase of +23% and +21% in compression strength for rectangular coupon specimens and omega cross-sectional components, respectively. Furthermore, the numerical simulation showed the same increase in strength of +21% for omega cross-sectional components. This work has proven the necessity of considering the strain rate dependency of a composite material to accurately predict the maximum load capacity of a structure during a dynamic load event like a crash.

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This study deals with a newly developed fixture to obtain strain rate-dependent properties of carbon fiber reinforced plastics (CFRP) under flexural loading. While the quasi-static method is mostly state of the art and covered in standards, the dynamic testing of CFRP is very demanding in terms of testing procedure, test rig and occurring failure mechanisms . @en