Shape design of Noise Barriers using evolutionary optimization and boundary elements

Abstract

Evolutionary algorithms have been widely used for Shape Design Optimization. It is a problem handled in many fields of science and engineering, e.g., aeronautics or solid mechanics. In this work we propose the application of this methodology based on evolutionary algorithms, to the shape design of a noise barrier. Noise Barriers are widely used for environmental protection in the boundaries of high traffic roads near population nucleus in order to reduce the noise impact. A bidimensional problem of sound propagation in the frequency domain is handled. This problem is constituted by an emitting source of fixed position, which pulses in a frequency range, and a receptor. Between the source and the receptor a generic shape obstacle (noise barrier) is situated. The shape of this barrier is modified to minimize the measured sound level in the receptor. The sound level is calculated using the Boundary Element Method (BEM), being known: the source and receptor position, the barrier shape, and the sound frequency. The objective function to maximize is the difference between the sound level in the receptor with and without barrier, respectively (insertion loss IL). In the performed analysis, a maximum limit to the effective height of the barrier is imposed. First, an inverse problem using the IL barrier curve as reference is successfully performed. Finally, improved performance barriers are obtained, showing the potential of the exposed technique. © 2006 Civil-Comp Press.