Structural Reliability Evaluation and Optimization of a Pressure Vessel Using Nonlinear Performance Functions

Abstract

Structural safety is one of the most important factors of any aerospace product. Until recently, a design is considered to be robust if all the variables that affect its life has been accounted for and brought under control. The meaning of robustness is changing. Designer and engineers have traditionally handled variability with safety factors. In this chapter, in the first phase, a pressure vessel made of titanium alloy is considered for safety index (structural reliability) study. The safety index is evaluated based on the data collected during manufacturing and operation. Various methods like mean value and moment methods are used for safety evaluation and same have been discussed. In the second phase of this chapter, an attempt has been made to carry out multi-objective design analysis taking into account the effect of variation of design parameters. Multiple objective of interests include structural weight, load-induced stress, deflection and structural reliability. The design problem is formulated under nonlinear constrained optimization and has been solved. Nonlinear regression relations are used for various performance functions. Nonlinear regression model is validated and found to be in good agreement with experimental results. Finally, optimum design parameters are suggested for design operating conditions.