| Summary: | 碩士 === 國立中興大學 === 機械工程學系 === 90 === The purpose of this thesis is to create a finite element model with stiffness and damping of interfaces modeled correctly. The modal test is performed to identify the stiffness and the damping of interfaces. The modal tests measure the natural frequencies, mode shapes and modal damping ratios. The optimization method is then used to modify the finite element model so that the optimized model can produce results as close to the measured data as possible.
Instead of using spring and damper elements to model the interfaces, interface elements are used. Considering the different stiffnesses in the three orthogonal directions, three dimensional orthotropic material is used. The design variables are the Young''s moduli, shear moduli and structural damping coefficients of the interface elements. The objective is to minimize the differences between measured and analyzed frequencies and modal damping ratios. The modal assurance criterion is used as constraints. The genetic algorithm is used to find the optimum solutions. The results produced by the modified finite element model will be close to the measured data.
The effects of the types of bolted joints, the tightening torques and the diameters of bolts on the design variables have been discussed.
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