A powerful tool for design optimisation of large structures

Engineers have to choose among many competitive solutions when designing complex structures in order to find the designs that merit further development and analysis. This task is often in contrast with the constraints on time and computational resources. For this reason, optimisation techniques are very useful if they allow engineers to obtain a large set of designs at low computational cost. Amongst the different optimisation methods, Sequential Linear Programming (SLP) is very popular because of its simplicity and because linear solvers are easily available. Despite of their theoretical simplicity, “well coded” SLP algorithms may outperform more sophisticated optimisation methods. A practical problem in engineering design is the optimisation of truss structures. This paper presents the experiences done in design optimisation of large scale truss structures with SLP based algorithms. Sizing and configuration problems of structures under multiple loading conditions with up to 200 design variables and 3500 constraints are considered. The relative performance and merits of some SLP based algorithms are compared and the efficiency of an advanced SLP based algorithm called LESLP is tested. Results of optmisations are also compared with Sequential Quadratic Programming that is considered a very well theroretically founded optimisation method. The aim of the present paper is to show that LESLP is a very powerful design tool in designing large scale truss structures.