考虑艉轴架结构刚度耦合的艉轴架强度计算

通过分析现行规范关于艉轴架强度的计算理论,发现该理论未考虑艉轴架结构刚度耦合作用。因此,针对艉轴架结构的受力特性,建立考虑艉轴架刚度耦合的艉轴架反力计算模型,推导出考虑艉轴架刚度耦合作用的内力计算公式,定义描述结构刚度耦合作用的“广义刚度比”参数,并将该公式与现行计算公式进行无量纲化对比。以某船艉轴架结构为例,对其分别采用有限元模型仿真、本文计算理论和现行不考虑艉轴架刚度耦合的计算理论等3种方法进行定量计算,并提出艉轴架扭转刚度的计算方法。结果表明:基于本文考虑耦合的内力计算理论的计算结果与有限元仿真结果符合良好,不考虑耦合的现行计算理论的计算结果与有限元仿真计算结果相差较大;现行不考虑耦合的内力计算理论使艉轴架截面内应力计算结果偏大,且随着“广义刚度比”的增大而严重,从而可能导致“艉轴架结构强度的过度设计”。

Strength calculation considering structural stiffness coupling of shaft bracket

In this paper, the current specification concerning strength computing theory of shaft bracket is analyzed, and it is seen that structural stiffness coupling is not considered in this theory. In the view of the shaft bracket structural and mechanical features, the reaction force model of shaft brackets considering structural stiffness coupling is established, and the calculation formulas for the internal forces of the shaft brackets are derived, and the parameters of the generalized stiffness ratio describing the structure stiffness coupling effects is defined. Taking shaft brackets of a certain boat as an example, the quantitative calculation on FEM simulation, the computing theory presented in this paper, and the conventional computing theory without considering structural stiffness coupling are applied, respectively. In addition, the computing method on torsional rigidity of shaft brackets is also put forward. The results show that the computing theory of this paper agrees well with the FEM simulation, while the conventional theory deviates far from the FEM simulation performance. Moreover, the conventional theory yields larger result, which further worsens with the enlargement of the generalized stiffness ratio, causing the overly design of the shaft bracket structure strength. In brief, the computing theory proposed in this paper serves as great guidance to the optimization in the strength design of the shaft bracket structure.