Structural Safety Assessment of a Pressure Vessel Using Performance Functions Approximations

Structural safety is one of the most important factors of any aerospace product. Until recently, a design was considered to be robust if all the variables that affected its life has been accounted for and brought under control. The meaning of robustness is changing. Designers and engineers have traditionally handled variability with safety factors. In this paper a pressure vessel made of titanium alloy is considered for structural reliability (safety index) study. The safety index is evaluated based on the data collected during manufacturing and operation. Various methods used for safety evaluation have been discussed. Design Of Experiment (DOE) and Two Point Adaptive Nonlinear Approximations (TANA) are used to establish the performance functions. These relations are very useful when exact parametrical relations are not available. Moreover, these linear and nonlinear functional relations are useful in optimization problem formulation. The safety evaluation is also carried out with strength-stress interference method. The linear and nonlinear approximation models are validated and found in good agreement with experimental results