NESTEM: A Computational Tool to Perform Probabilistic Structural Analysis of Components Subjected to Uncertain Mechanical and Thermal Loading

Abstract

This paper presents an overview of a newly developed code, NESTEM that analyzes structural components subjected to varying thermal and mechanical loads. This program is an enhanced version of NESSUS and has all the capabilities of NESSUS. In addition, it allows one to perform heat transfer analysis. The basic heat transfer variables can be included as random variables along with the mechanical random variables to quantify risk using probabilistic methods and to perform sensitivity analysis. The analysis capabilities of NESTEM have been demonstrated by analyzing a cylindrical combustor liner. This analysis includes evaluating stresses and their variations at critical points on the liner using material properties, pressure loading and basic heat transfer variables as the random variables. The heat transfer variables are convection temperatures, film coefficients, radiation temperatures, emissivity, absorptivity and conductivity. Cumulative distribution functions and sensitivity factors, for stress responses, for mechanical and thermal random variables are calculated. These results can be used to quickly identify the most critical design variables, in order to optimize the design, to make it cost effective.

Probabilistic study of fluid structure interaction

“…NESTEM [14] is an enhanced version of NESSUS (Numerical Evaluation of Stochastic Structures Under Stress) developed by NASA Glenn Research Center. NESTEM maintains all the capabilities of NESSUS, including structural analysis using a finite element approach and adds three significant features, namely, heat transfer analysis, geometry generation and ceramic material property generation.…”