An investigation into the combined effect of strain rate and temperature on the in-plane shear response of IM7/8552

Abstract

Continuous fiber reinforced structures used in lightweight aerospace, defense, and automotive applications may be subjected to impact loads while operating under varying temperature conditions. In order to accurately predict the behavior of these materials under these extreme conditions, a temperature chamber has been developed and implemented on a split Hopkinson Tension Bar. The new setup has been used to realize - for the first time - in-plane shear tests on the aerospace grade material IM7/8552 at a strain rate of approx. 1000 1/s and temperatures ranging from −54 °C to +121 °C. The test results are post-treated using different approaches and compared with results treating decoupled thermal and strain rate conditions available in the literature. The results showed that shear strength of the material decreases linearly with temperature and that corrected strength increases logarithmically with strain rate at all three temperatures in an equivalent manner. The conducted investigations enable to conclude that superposition of strain rate and temperature, as used in many simulation models, appears to be valid for the considered material. Finally Scanning Electron Microscope pictures give insights into the micro-scale failure mechanisms involved at the various testing conditions.