Exploring isospectral spring-mass systems with firefly algorithm

Abstract

This paper investigates in-line spring-mass systems (An), fixed at one end and free at the other, with n-degrees of freedom (d.f.). The objective is to find feasible in-line systems (Bn) that are isospectral to a given system. The spring-mass systems, An and Bn, are represented by Jacobi matrices. An error function is developed with the help of the Jacobi matrices An and Bn. The problem of finding the isospectral systems is posed as an optimization problem with the aim of minimizing the error function. The approach for creating isospectral systems uses the fact that the trace of two isospectral Jacobi matrices An and Bn should be identical. A modification is made to the diagonal elements of the given Jacobi matrix (An), to create the isospectral systems. The optimization problem is solved using the firefly algorithm augmented by a local search procedure. Numerical results are obtained and resulting isospectral systems are shown for 4 d.f. and 10 d.f. systems. © 2011 The Royal Society.