Document Type
Thesis
Date of Award
1-31-1986
Degree Name
Master of Science in Mechanical Engineering - (M.S.)
Department
Mechanical Engineering
First Advisor
Michael Pappas
Second Advisor
Bernard Koplik
Third Advisor
Harry Herman
Abstract
This thesis describes the optimal design of bar type planar truss structures subject to stress and buckling constraints. All of the structures considered are modeled using the direct stiffness finite element approach. A mathematical programming method incorporating a feasible directions routine is utilized to develop least weight designs for these conditions. The existing structural optimization programme CADOS which has successfully solved stress and deflection problems for this class of structures is adapted herein to treat local stability constraints based on Euler bucking criteria.In addition the optimization routine is modified to more effectively treat, infeasible starting designs. These modifications were tested on 3, 5 and 10 bar indeterminate structures. The solution to the 3 bar problem converged to a global optimum of 1399.5 lbs. ]n the 5 bar trial, a global optimum of 2295.4 lbs and a local optimum of 3958.6 lbs was identified. A similar result was obtained for the 10 bar case where the solution converged to a global optimum of 8034.5 lbs or a local optimum of 8300.4 lbs. depending on the starting design chosen. The results demonstrate the effectiveness of the boundary restoration scheme developed herein and in addition confirm the reliability of the basic algorithm in the optimum design of structures of this type. The method is therefore considered to have considerable potential in the optimization of large scale structural systems.
Recommended Citation
Looby, Thomas G., "Optimum design of structures subject to buckling constraints" (1986). Theses. 3430.
https://digitalcommons.njit.edu/theses/3430
