Please use this identifier to cite or link to this item: `http://hdl.handle.net/11455/1486`
 標題: 螺栓接合界面之簡易模擬方法和驗證A Simple Modeling Method for Bolted Joints and Its Identification 作者: 簡建宏Chien, Chien-Hung 關鍵字: genetic algorithm;遺傳演算法;bolted joint;stiffness;damping;螺栓連接;勁度;阻尼 出版社: 機械工程學系 摘要: 本文的目的是使有限元素模型能夠正確的模擬螺栓接合界面之剛性與阻尼，因此利用模態實驗來修正有限元素模型以符合實際的動態響應。先由模態實驗去量得自然振動頻率、局部模態及阻尼比，再使用最佳化設計方法去修正有限元素模型，使得修正後之有限元素模型的分析結果接近模態實驗量測的結果。 在修正的過程中，以界面元素做為螺栓接合界面的模擬，以取代傳統的彈簧元素和阻尼器，由於接合界面的勁度在三個正交方向可能不同，所以本文使用三維異向性材料來模擬界面元素，以楊氏係數、剪力模數和結構阻尼係數為設計變數，以模態相似性為限制條件。並且嘗試以遺傳演算法做為求解最佳化的方法，反覆修改界面元素的楊氏係數、剪力模數和結構阻尼係數，以減少分析所得之自然振動頻率、模態阻尼比與量測值的差，使得有限元素模型之動態特性與模態實驗結果接近。 最後，針對不同的螺栓接合鎖緊扭力、接合方式和不同直徑的螺栓，對界面勁度和阻尼的影響做討論。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. URI: http://hdl.handle.net/11455/1486 Appears in Collections: 機械工程學系所