Mechanical characterization of steel/CFRP double strap joints at elevated temperatures

This paper examines the mechanical performance of steel/CFRP adhesively-bonded double strap joints at elevated temperatures around the glass transition temperature (T-g, 42 degrees C) of the adhesive. A series of joints with different bond lengths were tested to failure at temperatures between 20 degrees C and 60 degrees C. It was found that the joint failure mode changed from adherend failure to debonding failure as the temperature approached T-g. In addition, the ultimate load and joint stiffness decreased significantly at temperatures near to and greater than T-g, while the effective bond length increased with temperature. Based on the ultimate load prediction model developed by Hart-Smith for double lap joints and kinetic modelling of the mechanical degradation of the adhesive, a mechanism-based model is proposed to describe the change of effective bond length, stiffness and strength degradation for steel/CFRP double strap joints at elevated temperatures. The modelling results were validated by the corresponding experimental measurements. (C) 2011 Elsevier Ltd All rights reserved.