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由于准静态扩展裂纹存在着许多矛盾，而动态解当马赫数Ｍ→０时，又不能够退化为准静态解．因此，有必要引入新的本构模型来重新研究裂纹尖端场．作者采用弹粘塑性模型，对Ⅰ型扩展裂纹尖端场的渐近问题进行了研究，给出了平面应变情况下的本构方程．位移、应变、应力被用幂级数展开，因此揭示了场的渐近特性．由于粘性的引入，消除了塑性激波，而且当表征裂纹扩展速度的马赫数Ｍ→０时，动态解可以退化为准静态解，从而证明了准静态扩展解是动态解的特殊情况，使二者统一了起来
Since there are many contradictions in the quasi-static expansion crack, the dynamic solution can not degenerate into a quasi-static solution when the Mach number M → 0. Therefore, it is necessary to introduce a new constitutive model to re-study the crack tip field. The authors used the visco-viscoplastic model to study the asymptotic behavior of the type I crack tip field and gave the constitutive equation in the case of plane strain. Displacement, strain and stress are expanded by the power series, thus revealing the asymptotic behavior of the field. Due to the introduction of viscosity, the plastic shock wave is eliminated, and the dynamic solution can degenerate into a quasi-static solution when the Mach number M → 0 characterizes the crack growth rate. It proves that the quasi-static expansion solution is a special case of dynamic solution, Unification up