Date of Award

12-1990

Document Type

Thesis

Degree Name

Master of Science in Astronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Howard Gans, PhD

Abstract

This study identified techniques and software available for the optimization of doubly curved shells and applied them in the context of a large nozzle shape. An optimality criteria scheme that can reduce solution time was evaluated and compared to the Method of Feasible Directions. MSC/NASTRAN and ASTROS were used to perform finite element analysis and optimization, and the results were compared to the theory. The programs give virtually identical results, and if plates and shells are carefully modeled, then stresses, displacements and modes are accurate to within ten percent. A Mindlin-type axisymmetric finite element was implemented in ASTROS that preserved accuracy and reduced the size of the stiffness matrix by a factor of four. Nozzle optimization was performed using static pressure and thermal loads, constrained by the Von Mises stress criteria. Software errors were documented in ASTROS, and four characteristic stress regions identified for the optimized nozzle.

AFIT Designator

AFIT-GA-ENY-90D-4

DTIC Accession Number

ADA230682

Comments

The author's Vita page is omitted.

Download

Share

COinS