Modeling&Analysis And Applied Research Of Flexure Hinge With Constrained Layer Damping

A positioning platform with nanometer accuracy is the core module of nano-scale manufacturing system. In order to ensure the high efficiency and output during the manufacturing process, the platform based on the flexible hinge must have high speed, accuracy and stability, whose dynamics characteristics are one of the key issues. With the help of novel high-performance drivers, high-accuracy displacement sensors and stable controlling algorithm, the positioning system has higher speed and better accuracy. However, piezoelectric ceramic drivers with high force and response speed in the compliant mechanism are vulnerable to the signal excitation, which is easier to bring impact to the positioning platform. The positioning system has very small structural damping value, thus subjecting it to long-time residual vibration if impact vibration is introduced. In this thesis, a novel passive damping structure is introduced to increase the structural damping value of positioning platform based on flexible mechanism without any external power input.As the motion joint of compliant mechanism, flexure hinge is the key functional component and the weak link to influence the structural dynamic characteristics in the mechanism. To improve the dynamics performance, a passive damping structure was integrated into the flexure hinge and studies on the damping flexible hinge were conducted on the cell and system level, respectively. First, the theoretical model was established and the corresponding experiments about flexure hinge were conducted on the cell level, including the analysis and design of damping structure, the model building and optimization of dynamics system and loss factor, the experiments based on the leaf-type damping flexure hinge with constrained layer and shear-type flexure hinge with U-shape and their loss factor analysis using dynamic mechanical analysis. On the system level, the damping flexure hinge was applied on a typical one-dimensional compliant mechanism to study the vibration-reduced effect and dynamic response process.The results showed that the time and amplitude of free vibration response was greatly reduced for the flexure hinge integrating with damping material and constraint layer, allowing the flexure hinge to arrive at the target position with less time. By establishing the dynamic mechanical system model of damping flexure hinge, the influence factors could be analyzed, which could be taken into account to optimize the loss factor and obtain the expression in the certain frequency range when the loss factor model was derived. Furthermore, the dynamic mechanical analysis was conducted to reveal the appearance of peak value in the resonance frequency range for the loss factor. Last but not the least, the application on flexible mechanism has indicated that the response was improved especially in the high-frequency range under the phase step and sine signal stimulation and the vibration of the platform was effectively reduced during the positioning process.