工程结构裂纹在动态荷载作用下容易迅速扩展，导致结构发生低应力脆断破坏，严重影响结构的安全和正常使用。在广义参数有限元法分析框架下，建立动态荷载作用下裂尖动态应力强度因子（dynamic stress intensity factors, DSIFs）分析的Williams宏单元（W单元）。假定奇异区径向子单元各节点位移近似满足刚体转动理论，进而推导建立奇异区单元荷载向量近似求解式。利用Newmark积分为无条件稳定隐式算法的优势，求解模型的整体控制方程，并由相应的广义参数求解裂尖DSIFs。结合算例分析了W单元关键参数对裂尖DSIFs的影响，研究表明，当W单元的径向离散比例因子为0.95、径向离散单元数为400、级数项数为12时，W单元具有较高的计算精度。

Cracks in engineering structures are prone to rapidly propagate under dynamic loading, leading to low-stress brittle fracture failure, which severely impacts the safety of the structure. Within the framework of the finite element method with generalized degrees of freedom, the Williams element with generalized degrees of freedom (W element) was proposed for the analysis of DSIFs(dynamic stress intensity factors) of crack tip under dynamic load. The approximate solution of the load vector of the element in the singular region was derived by assuming that its displacement approximately satisfies the rigid body rotation theory. The global governing equation of the model was solved by Newmark integral method, and the corresponding generalized parameters were directly substituted into the formula to obtain DSIFs at the crack tip. Examples were employed to analyze the influence of key parameters of W element on DSIFs at the crack tip, investigation shows that the proposed method achieves higher calculation accuracy with the radial discrete scale factor is 0.95, the number of radial discrete elements is 400, the number of series terms is 12.