Potential gas turbine engine applications will expose polymer matrix composites to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these conditions. Specifically, the strain rate sensitivities and nonlinearities which are present in the material response must be simulated. The Bodner-Partom constitutive equations, originally designed to analyze the viscoplastic deformation of metals, have been modified to simulate the nonlinear deformation of polymers. The effects of hydrostatic stresses, which are significant in polymers, are accounted for in a rigorous manner. The polymer constitutive equations are implemented into a mechanics of materials based micromechanics method, in which the composite unit cell is divided into a number of slices. Micromechanics equations are developed for each slice, and laminate theory is applied to determine the elastic properties, effective stresses and effective inelastic strains for the composite ply. The micromechanics equations also compute the effective transverse shear properties and stresses for the composite ply, which are important for impact applications. Laminate theory can be applied again to obtain the effective properties and response of multilayered laminates.The ultimate strength of the composite plies are predicted using the Hashin and effective strain failure criteria. The methodology is implemented within a stand-alone computer code, but is also implemented such that it can be utilized within a transient dynamic finite element code.
|Original language||English (US)|
|State||Published - Mar 16 2005|