Accession Number : ADA112224

Title :   Panel Optimization with Integrated Software (POIS). Volume II. User Instructions-ECHO and RRSYS.

Descriptive Note : Final rept. Jun 76-Oct 80,

Corporate Author : LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CA PALO ALTO RESEARCH LAB

Personal Author(s) : Stern,P ; Almroth,B O ; Stehlin,P

PDF Url : ADA112224

Report Date : Mar 1981

Pagination or Media Count : 135

Abstract : Optimization of structural panels with respect to bifurcation buckling constraints tends to lead to imperfection sensitive panels. The panels may not represent least weight configurations if the influence of always present geometrical imperfections are taken into account. A software package, POIS (Panel Optimization with Integrated Software) was developed in response to this problem. Here user instructions are presented for Computer Program ECHO and RRSYS which are part of the POIS system. ECHO is a collection of computer programs for least weight design of stiffened structural panels subjected to multiple combinations of inplane loads. ECHO includes program modules for optimization of perfect panels and nonlinear static stress analysis of panels with random imperfections. The optimization problem is carried out as a constrained function minimization problem in which buckling loads, stress, and strain may be constraints. RRSYS is a program system for the nonlinear analysis of elastic structures by means of the Rayleigh-Ritz method. RRSYS is designed to analyze such diverse structural phenomena as collapse, linear and nonlinear bifurcation, vibrations and transient dynamic response. (Author)

Descriptors :   *Composite structures, *Panels, *Mathematical models, *Computer aided design, *Airframes, User needs, Instructions, Computer programs, Optimization, Buckling, Stresses, Strain(Mechanics), Stability, Stiffened cylinders, Sensitivity, Defects(Materials), Nonlinear analysis, Integrated systems

Subject Categories : Aircraft
      Laminates and Composite Materials
      Numerical Mathematics
      Computer Programming and Software

Distribution Statement : APPROVED FOR PUBLIC RELEASE