Uncertainty analysis of structural strength of stiffened panels

A prototype computational methodology for reliability assessment of continuum structures using finite element analysis with instability failure modes is described in this paper. Examples were used to illustrate and test the methodology. Geometric and material uncertainties are considered in the finite element model. A Computer program was developed to implement this methodology by integrating uncertainty formulations to create a finite element input file, and to conduct the reliability assessment on a machine level. A commercial finite element package was used as a basis for the strength assessment in the presented procedure. A parametric study for a stiffened panel strength was also carried out. The finite element model for the stiffened panel is based on the 8-node doubly curved shell element, which can provide the non-linear behavior prediction of the stiffened panel. The mesh is designed to ensure the convergence of eigenvalue estimates. Failure modes are predicted on the basis of elastic non-linear analysis using the finite element model. Reliability assessment is performed using Monte Carlo simulation with variance reduction techniques that consisted of the conditional expectation method. Conditional expectation estimates the failure probability in each simulation cycle, then the average failure probability and its statistical error are computed. The developed method is expected to have significant impact on the reliability assessment of structural components and systems. This impact can extend beyond structural reliability into the generalized field of engineering mechanics.