过渡状态下材料断裂韧性的计算方法

材料的断裂韧性对于损伤容限设计和评估技术非常重要,但采用传统的试验方法获得过渡状态下材料的断裂韧性需要大量的时间和费用.针对这些不足,提出了一种过渡状态下材料断裂韧性的计算方法.分析了三维裂纹尖端的三轴应力约束参数,利用材料断裂能量准则研究了断裂韧性与拉伸性能之间的关系,得到了在三向应力状态下Ⅰ型裂纹体断裂破坏时的断裂韧性与材料单向拉伸性能参数之间的关系表达式和过渡状态下材料断裂韧性的计算方法.计算了2219-T87铝合金在过渡状态下的断裂韧性理论值,并将其与试验结果和经验公式计算值进行比较.结果显示,理论计算值处于试验点范围内,小于经验公式计算值,且偏于安全.

Calculation method of fracture toughness of materials at transition state

The fracture toughness of materials is very important for damage tolerance design and assessment technology, while the test method to obtain the fracture toughness in the transition state is costly and time-consuming. In order to overcome these disadvantages, a determination method of fracture toughness based on calculation in the transition state was presented. The triaxial stress constraint parameter for the three-dimensional crack tip was analyzed, the relation between fracture toughness and material tensile properties was researched with the energy criterion for material fracture, meanwhile the relation expression in the three-dimensional stress state for I type crack fracture and the determination method of fracture toughness of materials based on calculation in the transition state were obtained. The fracture toughness in the transition state for 2219-T87 aluminum alloy was calculated with the determination method and empirical formula most of the theoretical calculation values were safer compared with test results and smaller than the values calculated by the empirical formula.