脆性材料破坏与莫尔理论存在的问题

BRITTLE MATERIAL DAMAGE AND MOHR'S THEORY

材料受力时应力状态不同,则断裂过程物理机理会发生改变,脆性材料受拉时发生的拉断与受压时发生的剪断,是两种不同物理机理的断裂形式,而莫尔强度理论用一个断裂条件解决这两种断裂形式的强度问题,是否合理需要讨论.结合灰铸铁HT200材料在不同受力条件下的断裂破坏试验,对此问题进行了研究,结果表明,莫尔理论对复杂应力状态下材料断裂不能合理、准确地进行强度计算.

Under different stress states, the physical mechanisms of the process of fractures can be different. Traction facture occurs when brittle materials are subject to traction, and shearing fracture occurs when they are subject to pressure, which are two kinds of fracture patterns with different physical mechanisms. The Mohr's strength theory uses only one fracture condition, which is questionable. This problem is studied in combining with fracture damage tests of grey cast iron HT200 materials. The results indicate that Mohr's theory can not rationally predict the strength of material fractures in the state of complicated stresses.