Use of Infinite Elements Technique for Computing Radiated Noise for a Transmission Oil Pan 2011-01-0149

It has been found during the transmission level test that oil pan is a major contributor of noise to the overall noise emanating from transmission. Oil pan being thin and having substantial surface area becomes a significant noise source. Keeping this in view it is very important to study the acoustic behavior of the oil pan. Several computational techniques are available to study the noise characteristics of such structures. Indirect techniques that compute normalized velocity distributions on the surface from frequency response analysis give a quick assessment of sound power of the structure but can't give the Sound Pressure Level (SPL) at microphone locations. Technique such as Boundary Element Method (BEM) can calculate the SPL but are computationally intensive as the size of the model increases. Infinite Element techniques overcome these shortcomings from the way they are formulated.

In the present study infinite element technique has been applied to study the cover noise of an oil pan bolted to a transmission. ABAQUS code has been used for this purpose. Finite elements are used to model the oil pan structure and the volume of the acoustic domain up to some distance from the pan. Infinite Element (IE) are created on the surface of FE volume domain and SPL as final solution are obtained at desired distance by interpolation function. The resulting SPL obtained from infinite elements are compared with those obtained from BEM (SYSNOISE). The SPL show a close match and the computational time obtained from Infinite Element technique is lesser compared to BEM.