以有限元素分析方法預估並量化振動應力消除之效果;Predicting and Quantifying the Effect of Vibration Stress Relief with Finite Element Analysis

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Title:	以有限元素分析方法預估並量化振動應力消除之效果;Predicting and Quantifying the Effect of Vibration Stress Relief with Finite Element Analysis
Authors:	金郁翔;Jin, Yu-Xiang
Contributors:	機械工程學系
Keywords:	振動應力消除;平均應力鬆弛
Date:	2021-08-16
Issue Date:	2021-12-07 13:29:22 (UTC+8)
Publisher:	國立中央大學
Abstract:	早期金屬加工件殘留應力的消除是使用退火熱處理的方式，但隨著工件尺寸或結構複雜性增加，單憑熱處理無法滿足生產條件，於是，振動應力消除(VSR)逐漸受到關注，它是一種基於低周疲勞理論，藉由材料內部殘留應力與外部負載疊加以產生塑性變形，達到應力重新分布，藉以減少工件內部應力之方法。至目前為止振動應力消除運作機制以及原理尚未明確的建立。在本研究中藉由有限元素模擬方法觀察材料SS400在循環塑性負載下的行為，即使用模擬的方法預估振動應力消除的效果，以達到建立振動應力消除方法的機制。本研究首先利用均勻圓棒模型進行材料參數之選用，並規劃一具缺口平板試片之循環塑性負載實驗，透過有限元素模擬之結果與實驗結果比對，確認所選擇之塑性材料模型與參數之適用性；接著使用具熱預應力之缺口平板試片，進行循環塑性負載模擬，以觀察有預應力之材料在進行循環負載時，循環施力與應力集中效應對於材料行為之影響；最後透過觀察應變變化速率，提供一即時估算並量化應力之變化量之方法。本研究模擬結果經過與實驗結果之比對，可以確立所使用之材料模型與參數之正確性，討論振動應力消除之力學機制，尋找較佳施力分法，並同時提供一種簡易的量化振動應力消除效果之方法;In the early day, the residual stress of metal processing parts was usually eliminated by annealing heat treatment. As the complexity of the metal structure increased, the heat treatment could not meet the production requirements. Vibration stress relief (VSR) has gradually attracted attention. The method of VSR is based on the low cyclic fatigue theory which suggest the reduction of the internal stress by superimposing the residual stress of the workpiece and the external loading to produce plastic deformation for stress redistribution. However, the mechanism of VSR have not clearly be understood so far. This research used, the finite element method to simulate the behavior of material SS400 under cyclic plastic loading, for predicting the effect of vibration stress relief. First, we chose the uniform round rod model to determine the material parameters of Chaboche model. Next, the simulation model of a notched flat piece was adopted because of its characteristic of uniformly distributer stress. The corresponding experiment was also conducted. The results of the finite element simulation were compared with the experiment results to confirm the correctness of the Chaboche model and the material parameters Finally, simulation of applying cyclic plastic load to the notched flat piece with thermal pre-stress was performed. The numerical results can provide the stress-reduction effects of various cyclic loading amplitudes and durations. The method have been proven a good approach to estimate the effectiveness of VSR method.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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