基于Hertz弹性接触的船舶推进轴系非线性校中计算

Non-linear alignment calculation of ship propulsion shaft based on Hertz contact theory

针对大型商船推进轴系中尾管后轴承,且尾轴在螺旋桨重量作用下存在弯曲变形,导致尾管后轴承后端存在边缘载荷的特点,研究了轴系校中计算中尾管后轴承Hertz接触模型的非线性建模方法。以第二代四十万吨矿砂船轴系为对象,采用平面梁单元,建立轴系校中有限元模型;同时将尾管后轴承分成多个轴承分段,使用Hertz接触模型模拟各个轴承段与轴的接触形态,并用迭代法求解了具有非线性边界条件的梁单元有限元模型。对根据尾管后轴承单支点模型的计算结果确定的几组尾管后轴承SLOPE值进行了计算对比。研究发现,基于Hertz弹性接触的尾管后轴承多点支承的非线性模型,可以得到尾管后轴承的最大接触压力、各个轴承段的支反力等分布情况,可以更好地优化尾管后轴承的SLOPE设置,要优于传统的单支点固定约束模型。

Aiming at the after stern tube bearing in propulsion shaft of large merchant ships and the propeller shaft has bending deformation due to the propeller weight,resulting in the edge load in the after end of the after stern tube bearing,the non-linear modeling method of after stern tube bearing of alignment calculation was reviewed based on Hertz contact theory.A new generation 400 000DWT VLOC was taken as a study case in the paper and the FE model of shaft alignment was built by plane beam element.The stern tube bearing was divided into several sections in the model where the contact status between each section and the shaft was simulated by Hertz elastic contact model.The FEM of beam elements with non-linear conditions was solved by means of iteration method.Comparing with several typical SLOPE values of after stern tube bearing in accordance with single point support model,the study revealed that the non-linear calculation model with multi-point support based on Hertz elastic contact obtained the maximum contact pressure and the distribution of bearing section force,etc.and optimized the SLOPE value of after stern tube bearing accordingly,gaining certain advantages over traditional single point support model.