Optimal study on sectional geometry of rubber layers and cavities based on the vibro-acoustic coupling model with a sine-auxiliary function

Abstract

The sectional geometry of sealing strips in an automotive door is generally in shape with a round bulb. It can be simplified to an idealized dual-membrane model to study the vibro-acoustic coupling characteristics. In the present study, a simple sealing model is adopted to investigate the sound insulation of the door seal. Among that, two flexible rectangular thin structures represent rubber layers and one cube represents the air cavity. The cavity mode with two coupling interfaces in the same direction is expressed as a Fourier cosine series with added simple sine-auxiliary function. The coupling frequencies obtained by the method of this paper are verified by literature results. This approach can enrich the vibro-acoustic coupling analysis of combined dual-membrane models. Then, two optimization setups using a modified simulated annealing algorithm are presented. Rubber layer height, layer thickness, the distance between layers are defined as design variables for optimal study on the radiated sound power of the two vibro-acoustic coupling models, in which the radiated sound power is numerically evaluated based on wavelet method. Optimized parameters of the sectional geometry make a corresponding annulus-shape model with significantly improved sound transmission loss. The effects study of sectional geometric parameters on radiated sound power exhibits that combined values of the height and thickness change coupling frequencies while increasing the distance between layers can lower the radiated power. The coupling characteristics explain the enhanced energy transmission in a particular frequency neighborhood. This work will open new avenues for the design of the cross-section shape of automotive bulb seals regarding sound insulation.