幂律非线性粘弹性材料中的裂纹扩展*
Crack Propagation in the Power-Law Nonlinear Viscoelastic Material
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摘要: 对蠕变不可压幂律非线性粘弹性材料中裂纹的蠕变扩展进行了分析,为描述银纹带中的力学行为,假设在裂纹尖端邻域中断裂过程区中分布着阻抗裂纹张开的粘聚应力бf,.通过对均匀应力参考状态平凡解的摄动,将非线性粘弹性问题化成线性问题处理.对于幂指数.n≌1的弱非线性情况得到了应力与位移表达式.提出断裂过程区局域能量判据,导出了裂纹孕育时间t*与蠕变扩展率a的预测公式.Abstract: An analysis on crack creep propagation problem of power-law nonlinear viscoelastic materials is presented, The creepincom pressibility assumption is used,To simulate fracture behavior of craze region, it is assumed that in the fracture process zone near the crack tip, the cohesive stress бf acts upon the crack surfaces and resists crack opening. Through a perturbation method, i, e.,by superposing the Mode-I applied force onto a referential uniform stress state, which has a trivial solution and gives no effect on the solution of the original problem,the nonlinear viscoelastic problem is reduced to linear problem, For weak non-linear materials, for which,the power-law ind,ea n≌1, the expressions of stress and crack surface displace went are derived. Then, the fracture process zone local energy criterion is proposed and on the basis of which the for mulae of crac-king incubation time t* and crack slow propagation velocity a are derived.
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