Enhancement of Damping Performance of CLD Treatment Using Segmentation Method 2017-01-1882
The reduction of vibration and noise is a major requirement for performance of any vibratory system. Due to legislative pressures in terms of external pass by noise limit of vehicles and customer requirements for better noise and ride comfort in vehicle, NVH attribute has become an important parameter. Major sources for vehicle pass-by noise consist of powertrain, tire and wind. Damping treatment is important to reduce vibration and noise radiation. The passive constrained layer dampening (CLD) treatment can be used to reduce structure-borne noise of vibrating structure using viscoelastic damping material. The performance of the passive constrained layer damping treatment can further be enhanced by new segmentation technique. The concept of segmented CLD is based on edge effect.
The efficiency of segmenting a constrained layer damping treatment relies on the fact that a high shear region is created in the viscoelastic layer. The shear deformation in the viscoelastic material is not significant in regions where the bending moment is maximal. Segmenting induces shear in the damping layer and thereby increases damping ability. A cut in the damping treatment gives an additional shear deformation at that position. Hence a cut has to be located at the maximum displacement. The position of maximum displacement for all the first four bending modes is identified by bending mode shape. The bending mode shapes are obtained by MATLAB program. The damping performance is further increase by using multiple cuts in CLD beam. The optimized positions of multiple cuts are obtained by Genetic Algorithm (GA) optimization technique. The damping performance of CLD beam is measured in terms of vibration response (dB) and composite loss factor (η).This paper focused on comparison of damping performance of full CLD treatment and segmented CLD treatment. The experimental investigation is performed by using Accelerometer, Impact hammer and FFT analyser ( B&K make ). The new innovative segmented CLD treatment is found to be very much effective.