梁在纯弯曲作用下的脆性断裂

脆性梁在纯弯曲断裂时会产生多个碎片, 其断裂过程直接影响弯曲波的产生和传播, 以及产生碎片的平均尺度. 采用内聚力断裂模型对脆性梁的弯曲断裂过程进行有限元数值模拟, 再现了断裂中的裂纹扩展过程, 分析了脆性梁断裂后断裂面弯矩与裂纹张开角之间的规律. 数值结果表明: (1)在一个广泛的材料参数和加载应变率条件下, 断裂面弯矩与裂纹张开角之间均呈相似的单调衰减规律; (2)断裂过程中弯矩做功与断裂面的表面能一致; (3)在纯弯矩作用下, 裂纹前端总是存在压应力区域, 使得断裂末期应力状态较为复杂, 断裂不再是纯弯曲状态.

Brittle fracture of beams under pure bending

A brittle beam produces multiple fragments during a pure bending fracture. The fracture process directly affects the generation and propagation of bending waves and the average fragment size. The cohesive fracture model is used to simulate the bending fracture process of the brittle beam. Such FEM modeling reproduces the crack propagation process in the fracture and analyzes the law between the bending moment and the fracture surface-cracking angle after the brittle beam fracture. Numerical results show that: (1) Under a wide range of material parameters and loading strain rates, there is a similar monotonic attenuation law between the bending moment and the cracking angle of the fracture surface; (2) The fracture energy of the fracture surface is equal to the bending moment work during the fracture process; (3) Under the action of pure bending moment, there is always a compressive stress region at the crack tip, the stress state at the end of the fracture is hence more complicated, and the fracture is no longer a purely bending state