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这里所说“弹塑性材料”是指塑性良好的金属材料,如有裂缝存在,在载荷作用下,裂缝开裂前先在其尖端产生大量的塑性变形。若用尺K_(Ic)法测定这种材料的断裂韧度是困难的,因为为了达到基本上符合线弹性理论的条件,不能不用厚度很大的试件,借以限制塑性区的发展。这是事实上往往做不到的,而且实际上也使测定工作失去了意义。一般来说,化工厂压力容器用钢材就属于这一类材料。 压力容器为什么迫切需要应用断裂力学? 过去化工厂用压力容器采用的是20g、20MnMo一类低强度钢材,其屈服强度一般在25至35公斤/毫米~2范围内,塑性比较良好。容器直径最大不超过1米左右。自化工厂向大型化发展以来,
Here, the term “elastomer-plastic material” refers to a plastic material with good plasticity. If there is a crack, under load, a large amount of plastic deformation occurs at the tip of the crack before cracking. It is difficult to measure the fracture toughness of this material by using the K_(Ic) method, because in order to achieve the conditions basically conforming to the linear elasticity theory, it is not necessary to use a test piece with a large thickness in order to limit the development of the plastic zone. This is actually impossible to do in fact, and it actually makes the measurement work lose its meaning. In general, chemical steels used in pressure vessels fall into this category. Why pressure vessels urgently need to apply fracture mechanics? In the past, pressure vessels used in chemical plants used low-strength steels such as 20g and 20MnMo, whose yield strength was generally in the range of 25 to 35 kg/mm~2, and their plasticity was relatively good. The maximum diameter of the container should not exceed approximately 1 meter. Since the development of large-scale chemical plants,