本研究利用有限元素法建立一套應用於家用空調迴轉式壓縮機定子與外殼鋼管干涉配合組裝之電腦輔助工程分析技術。首先，建立一套模擬分析定子與外殼鋼管干涉配合相互作用之有限元素模型，並利用實驗驗證模擬分析之結果，確認該模型之有效性之後，再進一步建立其動態摔落模型，用來預測該組合件之可承受摔落高度。在該組合件之結構應力應變分析模擬中，將會探討定子與外殼間的干涉量及定子層數對組合件之應力分佈、定子內徑之徑向位移以及定子與外殼鋼管間之徑向內力的影響。 藉由比較實驗與模擬之定子與外殼鋼管間最大靜摩擦力來驗證該有限元素模型之有效性，發現模擬結果與實驗結果有一致的吻合。在實驗中發現，定子與外殼鋼管間的干涉量及定子的傾斜度為最大靜摩擦力之重要影響因素。在模擬分析中，接觸面稜角之等效應力、定子內徑之徑向變形以及定子與外殼鋼管間之徑向內力三項數值，在定子上下20層的模擬值變化劇烈，且不論其定子之總層數為多少，其數值相近。當定子層數超過40層時，中間層區各層之應力與變形模擬值十分相近。另外，最大徑向位移以及定子與外殼鋼管間的最大靜摩擦力與干涉量有著線性關係，此乃該組合件僅承受彈性變形之故。 進一步利用板殼元素取代中間層區定子之簡化模型進行模擬分析，其結果與原實體元素模型之差異於工程應用中為可接受的程度，且計算時間可從40至50小時縮短為8小時。在動態摔落分析中，考慮三種不同的摔落高度，分別為1、0.5和0.25公尺。於模擬結果發現，40層定子與外殼鋼管之0.5毫米干涉組合件的不分離最高可接受摔落高度為0.5公尺。 ;The objective of this study is using finite element method (FEM) to develop a computer-aided-engineering (CAE) technique for application in interference fitting of motor stator and outer shell of a rotary compressor used in household air conditioning. An FEM model is developed to simulate the reaction between the stator and outer shell under interference fit. After validation by mechanical test, the FEM modeling is applied to simulating dynamic falling and predicting the critical falling height. The effects of interference between stator and shell and number of stator layers on the deformation and stress in the stator/shell assembly are considered in the simulation. The inner radial deformation of stator, radial reaction force between stator and outer shell, and stress distribution in the stator are calculated and correlated with the given parameters. The FEM model is validated by comparing with the simulation the maximum friction force between stator and outer shell measured in mechanical test. Good agreement is found between the simulation and experiment for the maximum friction force to move the stator. In mechanical test, it is found the slope of stator and the interference are the major factors in determining the maximum static friction force. It’s observed in simulation the value of von-Mises stress at the nodes of contact corners of stator, the radial displacement of inner surface of stator, and the internal radial force between stator layer and outer shell at the top 20 layers and bottom 20 layers vary significantly and are similar for all given total numbers of layers in stator. If the stator has more than 40 layers, the stress and deformation in the middle layers do not significantly change. In addition, the maximum radial displacement of stator and the maximum static friction force at the stator/shell interface have a linear relationship with the extent of interference due to elastic deformation. The FEM model is simplified using plate elements in the middle layers and the difference in results between the original solid-element model the simplified plate-element model is acceptable in engineering application. The computational time is effectively reduced from 40-50 hours to 8 hours using the simplified plate-element model. In the dynamic falling simulation, there are three falling heights considered, namely 1, 0.5, and 0.25 m. A critical falling height of 0.5 m is predicted to separate the stator from the outer shell during falling, for a given 40-layer stator/shell assembly with 0.5-mm interference.
