Hybridized optimization algorithms for design of trusses with multiple natural frequency constraints. (January 2015) - Kaveh, A.
Abstract: In this paper, two optimization algorithms are applied for finding the optimal mass of truss structures with natural frequency constraints. The Particle Swarm Optimization with an Aging Leader and Challengers (ALC-PSO) algorithm is the first technique which applies the aging mechanism to particle swarm optimization (PSO) algorithm. The second method is HALC-PSO that transplants harmony search-based mechanism to ALC-PSO as a variable constraint handling approach. In these methods, the leader of the swarm ages and has a limited lifespan which is adaptively tuned according to the leader's leading power. If a leader shows a strong ability to lead the swarm toward better positions, its lifespan is increased, otherwise the leader gets aged quickly and when its lifespan is exhausted, a new particle emerges to challenge and claim the leadership. Therefore, premature convergence can be prevented in these methods. Five well-known truss mass optimization examples on Layout and size with frequency constraints are presented to demonstrate the viability of the algorithms. This type of problem is highly non-linear and non-convex dynamic optimization problems since mass reduction conflicts with the frequency constraints, especially when they are lower bounded. Numerical results show the robustness and high performance of the ALC-PSO and HALC-PSO algorithms for structural optimization problems with frequency constraints. It is found that the best results are obtained using HALC-PSO algorithm in most of the cases.