Reduction of dynamic response of a bar using constrained layer damping composite structure

The bar structure has been widely used in products and equipment. The tool holders of cutting machines and the support bars in processing are prone to vibration under the unstable excitation. Firstly, a universal and general-purpose constrained layer damping composite bar is proposed to reduce dynamic response for the bar structure. The composite bar can reduce vibration through adding the damping ratio and compensates stiffness. The constrained layer damping structure of the composite bar are consisted of constrained layer, damping layer and substrate. Secondly, the modal characteristics of the composite bar are analysed. According to the modal characteristics calculation and the optimization principles of reduction vibration, the geometric parameters of the composite bar are determined. And 42CrMo steel, four viscoelastic materials and the hard metal are chosen as the materials of substrate, damping layer and constrained layer, respectively. Finally, the modal tests for the composite bars with various materials are performed. The constrained layer damping composite structure is optimized by the test result. The optimal constrained layer damping composite bar can increase the damping ratio by 400% and can reduce the vibration obviously.