Topology optimization of periodic microstructures for enhanced loss factor using acoustic-structure interaction
JungHwan Kook(Technical University of Denmark)
Nederland | International Journal of Solids and Structures
2016-08-28 | 바로가기
Cited by 19
■ View full text
International Journal of Solids and Structures
Received 28 August 2016, Revised 24 April 2017, Accepted 1 June 2017, Available online 7 June 2017.
Junghwan Kook, Jakob S.Jensen
Department of Mechanical Engineering, Technical University of Denmark
In this work we present a topology optimization method for the design of 2D composite materials with a distribution of a solid constituent and a lossy acoustic medium for obtaining high loss factors. The method is based on a mixed displacement-pressure finite element (FE) formulation combined with the Bloch-wave condition. We solve the resulting FE eigenvalue problem on a repetitive unit cell with periodic boundary conditions and use a complex k(ω) eigenvalue formulation to compute the loss factor. We consider the optimization problem of maximizing the loss factor in a target frequency range with an additional constraint on the stiffness. In the provided example we demonstrate the effect of combined local resonators and acoustic resonances of similar frequency for creating an enhanced overall loss factor of the material.
In this paper we have presented a gradient-based topology optimization method for the design of 2D periodic structures with a lossy acoustic medium for maximizing the loss/attenuation of propagating waves. The work encompassed the derivation of a computational model based on a mixed displacement and pressure finite element discretization of a periodic unit cell and a complex eigenvalue problem with a prescribed frequency. Maximization of the loss in a target frequency range was considered as the objective function for the optimization in order to obtain the largest possible wave attenuation by combining the effects of favorable distribution of solid material and an acoustic medium with dissipation. In the design example we found that the optimized design has a locally resonating internal structure combined with acoustic modes with frequencies close to those of the resonators. It was shown that the acoustic-structure interaction in the optimized microstructure caused an increased overall loss factor and that the presence of the lossy acoustic medium had strong effect on the wave decay of the periodic structure. We conclude that the proposed loss optimization presented here works well for creating a favorable distribution of a lossy acoustic medium and a stiff constituent in order to enhance the damping properties of the composite material.
* 관련 자료