A Study on the Structural Parameters of Joint Interface

Abstract

The correctness of simulating results from the finite element analysis software is closely related to the way to define the joint interface between structures. In this study, aim to get the closely result of experiment and simulation, we do modal testing and simulation and compare the results of the experiment and simulation for the single structure. After confirming the results of the simulation and experiment are similar, doing modal testing of the combined structure and repeat the experiment after changing the conditions of joint interface. We can get the equivalent stiffness and damping matrices of joint interface by using the method of parameter identification. Finally, substitutes the matrices into the contact condition of finite element analysis model to do the analysis. During the calculation of the parameter identification formula, it's been found that is not necessary to measure whole structure to get the parameters of joint interface but only measure specific position of the structure. After the experimental of measure, the parameters of joint interface can be get through the appropriate formula. According to the results of the experiment and simulation in this study, there have larger error between simulation and experiment if we simplify joint interface directly during the finite element analysis. We should consider the contact way of the joint interface being the basis to choose appropriate contact condition in the finite element analysis, so that we can get the closely result of experiment and simulation. We can also know that if the form of design structure is satisfy the design requirement or not by the experiment and simulation of changing the contact condition.

結構與結構間的接合界面如何設定，與有限元素分析軟體的模擬結果是否正確密切相關。本研究先透過針對單一結構進行模態實驗與模擬，並比對試件的實驗與模擬結果；確認實驗與模擬結果相符後，再進行組合結構的模態實驗，改變接合界面的結合條件，依序進行實驗，並透過接合界面參數辨識方法進行參數辨識後，得到結合界面的等效剛性與阻尼矩陣，並依此代入有限元素分析軟體進行分析，使模擬結果更趨於實驗結果。 在接合界面參數辨識的公式計算過程中可發現，並不需要對整體結構進行量測，只須量測單一結構與組合結構在接合界面連接點位置的頻率響應函數，透過適當參數辨識方法，即可獲得結合界面的特性參數。 由本研究的實驗與模擬結果可看出，在有限元素分析模型的簡化過程中，直接將接合界面進行簡化，其模擬結果會與實際產生較大的誤差，應考慮接合界面的狀況，選擇適當的接觸條件進行模擬分析，其模擬結果較為趨近實驗結果，同時透過改變接合條件的實驗與模擬可看出，設計之結構的接合面狀況是否符合設計的需求。