Braodband vibration reduction of plate using Topometry and Topology optimization

Abstract

Almost engineering industrial structures such as home appliance and automobile are made of light and thin plates, which is vulnerable to vibration and noise. So, methods for reducing vibration and noise on a light and thin plates have been studied in industry. Because engineering systems are mass-produced, even if there is an effective method to reduce vibration and noise, it can’t be applied unless it is suitable for mass production. Therefore, to reduce vibration and noise, bead pattern, thickness distribution of plate and attaching damping material or other material are applied considering manufacturing for industry. These methods are determined considering the target frequency band in the system because those are different performance by target frequency band. In this research, in order to reduce vibration on the plate in a wide frequency band, two optimization methods were performed sequentially. The 1st method is Topometry optimization of plate to reduce vibration in the low frequency band. Topometry optimization is element-by-element sizing optimization. The design variable is thickness of element. This method optimized thickness distribution of plate. In the frequency response function of single degree of freedom, stiffness and mass are dominant at low frequencies. Topometry optimization of plate can be regarded as designing the reinforcement which increases mass and stiffness. The 2nd method is Topology optimization of damping layer attached on optimized plate. Damping layer has a feature of reducing vibration in high frequency band effectively. Constrained layer damping is used. Shear deformation occur by shear strains on plate attached constrained layer damping. This effect reduce vibration and noise. Topology optimization optimizes material layout using limited materials to increase structural performance. After performing Topometry optimization of plate to reduce vibration at low frequency band, Topology optimization of damping layer attached on optimized plate to reduce vibration at high frequency is performed. In this study, for verification of numerical results and experimental result, vibration was measured by the impact hammering test.