Abstract:The shock-resistant analysis method of a large marine gearbox system is studied. Compute the equivalent static stress under normal operation condition of the box and gear using static and nonlinear contact finite element method, extract the stress components from the result files of NX.Nastran. A coupling finite element model of box-bearing-shaft-gear is established. Then Calculate the dynamic stress generated by underwater explosion using DDAM(Dynamic Design Analysis Method), re-synthesis the static and dynamic stress components of the corresponding elements by Von-Mises Guideline. The dimensionless coefficient of remaining strength is introduced to assess the shock-resistant performance of the gearbox. To simulate underwater explosion environment, shock spectrum signal curve matched by the form of assembling dumped sinusoids is researched. The results of study provide theoretical basis for anti-shock performance assessment and shock isolation.