Static and Fatigue Strength of an Adhesive Bonded CFRP Butt-Strap Joint. The Effects of Stacking Sequence and Temperature

摘要

The objective of the program was to investigate both the effect of temperature as well as the effect of the orientation of plies directly adjacent to the adhesive layer on the mechanical properties of an adhesive bonded composite joint. Therefore, static and constant amplitude fatigue tests were performed on bonded double butt-strap joints at 70 C, RT and -50 C. Two joint configurations were tested which only varied in the stacking sequence of the bonded adhesive. In addition, analytical and numerical solution techniques were used to calculate the stress distributions in the configurations tested. The results of the tests indicated that temperature had a pronounced effect on the mechanical properties of the joint. The static strength was found to increase with decreasing test temperature. The fatigue performance of the joint was best at RT. Both an increase to 70 C and a decrease to 50 C had a detrimental effect on the fatigue resistance. The largest reductions occurred at 50 C. The stacking sequence in the straps had hardly any effect on the static strength of the joint. However, some effect was observed on the fatigue resistance, in particular when tested at RT. The highest fatigue lives were found for specimens having straps with 0 outer plies.