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1.序言对于大型机械零件和构件脆性断裂的防止,平面应变断裂韧性 K_(10)值可以作为设计应力计算的基础,这在确保安全方面似乎找到了一个光明的前景。然而,正如作者之一的横堀[1],[2]指出的那样,除了能完全满足平面应变状态的理想场合之外,断裂韧性值并不是材料的特性值,而是随着裂纹尖端塑性区的构成不同而不同。在循环载荷下的裂纹尖端塑性与单一负荷下的裂纹尖端塑性区,其构成是不相同的,因而对于疲劳载荷而言,最终急速断裂的条件不是 K_(10),必须用另一个量,即叫做疲劳断裂韧性的量来表示[3][4]。
1. INTRODUCTION For the prevention of brittle fracture of large mechanical parts and components, the value of the plane strain fracture toughness K_ (10) can be used as the basis for the design of stress calculations. This seems to have found a bright future in ensuring safety. However, as one of the authors, Horiuchi [1], [2] pointed out, the fracture toughness value is not the property value of the material except for the ideal case that can completely satisfy the plane strain state. Instead, as the crack tip plastic zone The composition varies. The crack tip plasticity under cyclic loading is not the same as the plastic zone at the crack tip under a single load, so the final rapid fracture condition is not K_ (10) for fatigue loading and must be replaced by another quantity, namely Known as the amount of fatigue fracture toughness to represent [3] [4].