Reliability-Based Modeling and Analysis of Advanced Composites
Final rept. 1 Aug 97-30 Jun 98
HOLLAND (PAUL) AND ASSOCIATES INC BRENTWOOD TN
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The objective of the Phase I effort was to incorporate high performance composite design methodologies with mechanistic failure models to predict the reliability of composite structures. The methodology was demonstrated on a helicopter rotor hub tapered test specimen. The specimen is subjected to a static axial load and an oscillatory angular displacement. The observed failure mechanism is an initial tension crack followed by internal delamination. The research effort developed a non-linear structural model of the rotor hub using the finite element program ANSYS in which the internal plies and the delamination were explicitly modeled. The output from structural model was fed into the Virtual Crack Closure Technique VCCT module to predict the strain energy that is required to cause delamination onset. The response surface analysis was used to develop a limit state equation relating the primitive input design variables to strain energy release rate. A Reliability Analysis framework using first order reliability method FORM was developed and integrated with the structural analysis modules. The FORM analysis estimated the probability of delamination onset as a function of cyclic lives and the relative importance of the primitive variables. Advanced mean value methods were also added to the reliability framework.
- Laminates and Composite Materials