Structural Failure Analysis Based on the Uncertainty of Mechanical Properties

The objective of this study was quantified of uncertainty design parameters and included their effects explicitly in structural analysis for evaluated reliability indexes. On the other hand، structural reliability methods are of little use if they cannot be used in conjunction with the best available software for current structural analysis. Hence، it becomes very important to couple structural reliability algorithms with finite element analysis of structural problems. So in this research such coupling can be performed. It is used an algorithm for evaluation of first and second order approximation of reliability indexes based on the finite element programs. In this algorithm the limit state function and relative’s gradient of uncertainty parameters computed using finite element model. So structural model directly analyzed without any approximation such as response surface methodology. Based on the probability of fracture mechanics، strain energy release rate is evaluated for isotropic and composite material to demonstrate the application of the algorithm. In the paper also، the Young’s modulus probability distribution is determined for 26 steel samples with over the 35 service life years.