Energy Finite Element Analysis Methods for Mid-Frequency NVH Applications

At low frequencies, the finite element method reliably predicts the dynamic response of structures. At high frequencies where modal density is high, statistical energy analysis (SEA) is a useful tool to determine the global dynamic behavior of the structures. SEA gives only the space frequency band averaged energy for each subsystem. In the mid-frequency range where both short and long waves are present, neither low nor high frequency approximation to the dynamic response is valid. In this frequency range, there is a need to utilize another technique to capture the dynamic response of the structure. In this study, the energy finite element analysis (EFEA) method is evaluated as a possible technique to close the mid-frequency analysis gap related to NVH analyses. EFEA gives spatial variations of energy density and power in each subsystem, and models localized damping treatment and localized power input. In this study, two benchmark problems are used to evaluate both the benefits and limitations of EFEA for the mid-frequency NVH analysis using the commercial EFEA code called Comet-EFEA.¹The benchmark problems are the sound transmission loss through a panel, and energy transmission between two beams with different cross-sectional areas. EFEA results for the two problems are compared with the corresponding results obtained by experimentation, conventional finite element analysis, and SEA to establish the applicability and limitations of EFEA for the mid-frequency NVH analysis of automotive components. EFEA provides excellent insight into energy transfer and dissipation through the structure but is limited by the ratio of the geometric dimensions to the wavelengths of interest.