Approximations in optimization of damage tolerant structures

Approximations for structural response and design sensitivities significantly reduce the computational cost of structural optimization. To be useful, the approximation must be accurate and computationally efficient. Damage tolerant design puts even more stringent computational demands on optimization procedures and approximations due to the large structural changes inherent in damage. A robust approximation is evaluated and extended to include design sensitivities. It is implemented in an optimization procedure and tested. It is shown that this approximation is accurate and efficient for damage tolerant optimum design of complex structural models. Last, a qualitative measure is developed and tested that estimates the computational savings using these approximations.