Analysis of the thermomechanical behavior of [0] and [0/90] SCS-6/Timetal 21S composites

Micromechanical modeling is used to determine the stresses and strains due to both mechanical and thermal loads in [0] and [0/90] titanium matrix composites (TMCs) subjected to processing and thermomechanical fatigue (TMF) loading conditions. The concentric cylinder model, due to its simple geometry as well as its capability to capture the three-dimensional aspects of the stress state in a composite, is used to determine the stresses in a unidirectional composite. A representative volume element of the composite is represented by two concentric cylinders with the core cylinder representing the fiber and the outer ring representing the matrix. The fiber is treated as elastic and the matrix is treated as viscoplastic with temperature dependent mechanical properties. The [0/90]s layup is modeled by modifying the concentric cylinder model and adding a parallel element to the [0] model and invoking strain compatibility and stress equilibrium in the loading direction. The modified concentric cylinder model is incorporated into the PC-compatible code FIDEP for an efficient and expedient analysis. Calculations are made for in-phase and out-of-phase TMF conditions for the unidirectional and crossply SCS-6/TIMETAL 21S composite