Experimental and numerical investigation of the strain rate-dependent compression behaviour of a carbon-epoxy structure

• Published in: Composite structures 2018-04, Vol.189, p.256-262
• Main Authors: Schmack, T., Filipe, T., Deinzer, G., Kassapoglou, C., Walther, F.
• Format: Article
• Language: English
• Subjects: Carbon fibre; Compression strength; Epoxy; Finite Element Analysis; Prepreg; Strain rate
• ISSN: 0263-8223; 1879-1085
• DOI: 10.1016/j.compstruct.2017.11.025

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.