The purpose of GENOPT (GENeral OPTimization) is to enable an engineer to create a user-friendly system of programs for analyzing and/or optimizing anything. The application of GENOPT is not limited to the field of structural mechanics. GENOPT is designed to handle problems with small databases, not large finite element models, although it might well be used to provide a user-friendly "shell" within which any analysis could be done. GENOPT is ideal for generating programs for optimizing objects the behavior (stress, buckling, vibration, etc.) of which can be expressed by relatively simple tables or formulas such as those that appear in handbooks, or for optimizing objects the behavior of which has been previously encoded in existing subroutines. The optimizer used in GENOPT, created by Vanderplaats, is called ADS.

When engineers embark on the task of designing an object that must survive certain environments during service, they often develop or use computer programs that analyze given, fixed configurations. If, under the various applied loads, a configuration appears to be inadequate, the engineer changes certain dimensions, materials, or other parameters, and the analysis is repeated. The design evolves by means of this "manual" iterative process, which may require the expenditure of much labor and the passage of many days. Should a certain configuration prove satisfactory, that is, should the analysis program or programs show that this configuration survives all the environments with adequate margins of safety, the engineer is sorely tempted to terminate the iteration process and accept the design even though, while feasible, it may not be optimum.

The step from simple analysis to automated optimization seems to be a difficult one for many engineers and their managers. In every field there are many proven computer programs that analyze things with given configurations and given environments. Therefore, workers in a field are willing to accept the results of computerized analyses and to use these results as a basis for decisions on what to do next. However, these engineers and managers often seem less willing at present to allow the computer to make decisions about how the dimensions and other properties of the configuration are to be changed in order to minimize cost, minimize weight, or meet some other objective. Entering the field of automated optimization seems scary and appears to require mathematical expertise not available in time to meet the goals of a design project.

The main purpose of GENOPT is to make this step into the world of automated optimization easy. If the engineer has formulas from handbooks such as Roark's (1954), design curves, and/or algorithms for predicting the behavior of given configurations, GENOPT, working with these analysis tools, will generate a program system that can find the "best" design in a user-friendly way.

The user of GENOPT does not need to know much about optimization as a mathematical discipline. The optimizer used in GENOPT is called ADS, created by Vanderplaats (Vanderplaats and Sugimoto, 1986; Vanderplaats, 1987). ADS is "hardwired" in the "0-5-7" mode, which is the reliable "modified-method-of-feasible-directions" branch of this widely used optimization software.

Image of section view of a truss

Graphic from AIAA 52nd Structures, Structural Dynamics, and Materials Conference, 2011, AIAA Paper 2011-1811.

For the past 15 years Dr. David Bushnell has been doing research on the optimization of shells of revolution and prismatic panels and shells in which GENOPT has been used in combination with BIGBOSOR4 and HUGEBOSOR4. In these applications, cited in several papers below, GENOPT has successfully been used to solve optimizations in which there exist fairly large data bases. Hence, GENOPT works well when the analysis is more complicated than the "simple tables or formulas such as those that appear in handbooks..." mentioned near the end of the first paragraph above.

For a gallery of the kind of problem that can be solved by GENOPT, see the slide show that is primarily composed of pictures taken from the long, illustrated abstracts of papers about GENOPT and results generated from executions of GENOPT.

Abstracts and Papers