Study On The Technics In Truss Structure Optimization

Introducing optimization concept into structures design procedure,structural performance can be improved,cost can be reduced and the resource can be saved considerable,altogether.It will be of benefitto only our economic interest but also oursociety,which fit our strategy of sustainable development.Therefore,the idea of structural optimization design were paid close attention to in more and more engineering field.Especially in aerospace,in which the structural mass was particularly sensitive,Optimization design achieved economics benefit greatly.However,the variousbarriers have to be removed when we applied structural optimization theory to structural design in different engineering fields.They may be encountered in solving mathematic equation,or in practical engineering considerationsThis paper focused on the mathematical programming method used in structural optimization.The primary theories of various nonlinear mathematicalprogrammingmethods,including simplex method,sequence linear program(SLP),sequence quadratic programming(SQP)and the method of moving asymptotes(MMA),were analyzed and compared.Their performances were checked by several classical numerical examples.The iterative procedures of two methods of moving asymptotesused in structural optimizationwere compared.The method of size optimization and shape optimization of truss structures under constraint of stresses and displacements was studied.Their sensitivities were derived.It was discovered that the optimal truss derived from the optimal truss-like was similarto later extremely.Their members and nodes were coincidence completely.The material volume of truss with fewer members increased little relative to optimal truss-like.Therefore it was suggested to take the optimal truss-like continuum as ground structure of truss to be optimized.It will improvethe optimization efficiency considerable and avoid numerical instabilities widespread in various numerical optimization method.The fully-stressed criterion,whichused in size optimization generally,was applied to size and shape optimizationof truss.Sectional area of members were determined by fully-stressed criterion.Stress constraints were not included explicitly,which decreased the number of design variables and constraints.Their sensitivities were analyzed.This method was verified by numerical examples.