Numerical and Experimental Study on the Acoustic Performance of Ni-based Superalloy Open Cell Foam

Abstract

Open cell metal foams can be used as efficient sound absorbers. Ni-based Inconel 625 superalloy foam has high temperature and corrosion resistance properties comparing to traditional aluminum foam, thus has potential working as sound absorbers in high temperature and harsh environment for aerospace or marine industry. This work studies the acoustic performance of open-celled Inconel 625 foams manufactured by a newly developed template replication process. The foam porosity and cell size can be controlled by the process, which are important factors to the sound absorption performance. The foam microstructure were analysed using X-ray microtomographic and SEM technology, showing typical open cell structures with a representative tetrakaidecahedron unit cell shape. Analytical formula were developed to predict the foam absorption coefficient based on geometrical parameters obtained from geometrical and microstructural analysis. Using the simple impedance tube setting, good agreement between numerical simulation and experimental results was obtained. IN625 foam with sound absorption coefficient as high as 80% have been successfully fabricated and its sound absorption performance has been successfully simulated in this work. This simulation work propose a simple yet efficient way to bridge the sound absorption performance of metallic foams with their microstructural and geometrical properties, which can be utilized as a design tool to consider the metal foam performance in noise control applications.