Thermal Effects on the Pin-Bearing Behavior of IM7/PETI5 Composite Joints

Abstract

Thermal effects on the pin-bearing behavior of an IM7/PETI5 composite laminate are studied comprehensively within this paper. Pin-bearing tests of several lay-ups at the operating temperatures of −129, 21, and 177°C are conducted to generate data on the effect of temperature changes on the pin-bearing behavior of the IM7/PETI5 material. A unique computational study investigating the factors influencing pin-bearing strength is performed for the [90,0]8s lay-up. A detailed three-dimensional finite element model is developed including the modeling of resin layers between plies in the laminate with a pin hole. Using a previously established technique, the pin-bearing problem was modeled assuming a rigid frictionless pin and restraining only radial displacements at the hole boundary. An original three-dimensional solution, where thermal residual stresses were combined with the state of stress due to pin-bearing loads was evaluated. The presence of thermal residual stresses were observed to intensify the interlaminar stresses predicted at the hole boundary in the pin-bearing problem. Furthermore, the research shows that changes in material properties drives pin-bearing strength degradation with increasing temperature. The thermal residual cure stresses then somewhat affect the extent that the pin-bearing strength changes with temperature. In general, thermal residual stresses were determined to be significant in affecting pin-bearing strength.