Study on analysis model for simulating hot cracking phenomenon at heat affected zone of weldment

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The object of this study is to make clear and obtain hot crack phenomenon at the heat affected zone (HAZ) of a weldedment from the view point of dynamics. Especially, the main object is to investigate and propose the three-dimensional thermal elastic-plastic analysis model/method for the weldment under the conditions of elevated temperature and large nonlinearity. The summary of this study is as following.The new-type of the three-dimensional thermal elastic-plastic analysis model/method was proposed and validated, which was able to apply for laser/electron-beam welding methods in addition to an arc welding method. The high-accuracy analysis with finite element method was able to be proposed by using the new-type special method of setting of a material constant at elevated temperature, of dealing of a molten metal, of setting of a heat source and so on.The new-type method for accurate and dynamic measurement of the temperature and strain at the elevated temperature zone very near the molten part was investigated and proposed. Moreover an actual measurement by using the proposed method was carried out. The proposed new-type analysis method was able to be validated by comparing the analysis result to the measurement result in detail.Furthermore, the new-type evaluating/prediction method for liquation cracking at HAZ of a weldedment was proposed based on the equivalent-plastic strain obtained from the above analysis method.