本文在４种材料３０ＣｒＭｎＳｉＡ，４０ＣｒＮｉＭｏＡ，４５钢和２０钢宏观与细观试验结果的基础上，对韧性细观断裂的随机性和模糊性进行了研究。以基于孤立空洞长大模型基础上的临界空穴扩展比模型为例，指出细观空穴形核半径和临界半径可以用对数正态分布描述，其它模型参量可以用正态分布描述。具体分析了这４种材料在不同应力状态和应变水平下的断裂特征，结果表明，考虑参数的随机性，即采用概率断裂力学方法，所得结果比传统的确定性断裂模型接近实验结果。文中进一步讨论了断裂状态的模糊性，提出了考虑断裂状态随机模糊失效慨率的计算模型，算例分析表明，断裂状态的模糊性是事物的本质特性，基于专家经验基础上的模糊断裂分析方法能较全面描述材料及试样的断裂问题。本文建立的方法也适用于其它断裂模型的分析．
Based on the macro-and mesco-experimental results of four steels ,30CrMnSiA,40CrNiMoA,No.45 and No.20,the random and fuzzy properties of fracture are studied.The isolated void model is used as an example,and the fracture occures as the void radius R is greater than the critical Rc. The void radius can be expressed as R=R0exp[C1exp(C2Rσ)εp](R0 is the initial void radius, Rσ the stress triaxiality,εp the plastic strain, C1and C2 are model parameters) .The initial and critical radii of voids are in lognormial distributions and the other parametrs in normal distributions. The calculated fracture characteristics of the four steels in different stress states and strains are more near to the experimental results taking the random fracture model than the deterministic fracture model.The illustrative calculation shows that fuzziness is the nature of fracture state,and with appropriate values the fuzzy model can agree well with the experimental results.
参考文献
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