A composite damage module and a user interface module will be developed and integrated into a commercial finite element code for 1) predicting the extent of damage and the mode of failure in composite structures resulting from service-induced mechanical and nonmechanical loads and 2) for estimating the life of composite structures with and without pre-existing damage.The development of the composite damage module will be based on the progressive damage model that was developed originally at Stanford University. The proposed module consists of a material simulator and a damage estimator. The material simulator calculates the effective mechanical properties of composites as a function of damage state in terms of fiber failure, matrix cracking, or delamination. The damage estimator predicts the state of damage for a given state of applied stresses or strains in composites which can be calculated by a commercial finite element code. The proposed interface module will provide a linkage between the commercial code and the composite damage module. As a result, the material properties of damaged composites and the corresponding damage state estimated from the module could be updated in the code incrementally during finite element calculations. Accordingly, damage accumulation and residual strength of large complex composite structures under service loads could be analyzed using the integrated finite element code.
Potential Commercial Applications:The proposed composite damage module combined with a commercial finite element code could enable users to predict service load-induced damage and to assess the impact of such damage on the residual stiffness and strength of composite structures with complex configurations such as motor cases, launchers, pressure vessels, fuselage, etc. By using the integrated code, expensive component testing in design could be reduced and more accurate structural integrity evaluation could be performed in maintenance. Accordingly, considerable expense could be saved in both government and private sectors.
