A Numerical Investigation of Thermal-related Matrix Shrinkage Crack and Delamination in Composite T-Piece Specimens Using a Modified Interface Cohesive Model

Abstract

This article numerically investigated the curing temperature effect on matrix shrinkage crack and the effect of matrix shrinkage cracking on delamination in composite T-piece specimens using a modified interface cohesive model with thermal effects accounted. Thermal relative coefficient was introduced to produce the relative thermal displacement in the formulation of interface cohesive elements. The thermal shrinkage crack in the deltoid region of T-piece was simulated. Effect of this thermal initial cracking on the prediction of dominated delamination [Chen, J., Ravey, E., Hallett, S., Wisnom, M. and Grassi, M. (2009). Prediction of Delamination in Braided Composite T-Piece Specimen, Composites Science and Technology, 69(14): 2363–2367; Chen, J. (2011) Simulation of Multi-directional Crack in Braided Composite T-Piece Specimens Using Cohesive Models, Fatigue & Fracture of Engineering Materials & Structures, 34(2): 123–130.] of T-piece under T-pull loading case was also studied. The investigation indicated that some improper restraints to T-piece specimens during the curing process will induce so called thermal shrinkage cracks in the deltoid region of T-piece. This sort of thermal related matrix shrinkage crack has limited effect on the capacity of T-piece to resist T-pull loading. Radius laminates are the main load carrier in the T-pull loading case. This modeling investigation supplied considerable information for the design and manufacture of T-piece related composite components under pulling condition. Further investigation considering loading cases such as bending and combination with bending and T-pull is suggested in the future work to explore general effects of thermal related matrix shrinkage cracking on delaminating.