泥泵轴端螺纹应力集中系数及其影响因素

泥泵轴端螺纹根部有较严重的应力集中效应，使得螺纹根部局部应力较大，在交变载荷作用下，泵轴易发生疲劳破坏，影响工程进度及经济效益。以某绞吸挖泥船舱内泵的轴端螺纹为研究对象，在ANSYS中建立泵轴端部二维轴对称有限元模型，计算了螺纹根部的局部最大应力及相应的应力集中系数，分析了螺纹根部倒角半径、螺纹牙高、螺距和螺纹位置对应力集中系数的影响。结果表明，应力集中系数随螺纹根部倒角半径的减小而增大；螺纹牙高度对应力集中系数的影响不大，可忽略；应力集中系数和螺距线性正相关；适当增大螺纹与轴肩间距有利于减小应力集中系数。本文计算所得应力集中系数可用于修正材料的S-N(应力-寿命)曲线，从而提高泵轴疲劳寿命预报的精确度，各因素的影响规律可为泵轴结构优化设计提供参考。

Research on Stress Concentration Factor and Its Influence Factors at the Shaft Thread of a Dredging Pump

Serious stress concentration effect often occurs at the thread root on dredging pump shafts, leading to high stress on the shaft end part. Under the action of alternating load, the pump shaft is prone to fatigue failure, which affects the project progress and economic benefit. In order to study the influence factors of stress concentration for the pump shaft, the trapezoidal thread at the end of the pump shaft of a dredging pump was numerically studied. A two-dimensional axisymmetric finite element model of the end part of the pump shaft was established in ANSYS, and the local maximum stress at the thread root and the stress concentration factor were calculated. Numerical analysis were carried out for the influence factors on the stress concentration factor, i.e., fillet radius at thread root, thread tooth height, thread pitch and thread position. The results show that the stress concentration factor increases with the decrease of the fillet radius of the thread root. The influence of screw height is insignificant and can be ignored. There is a linear positive correlation between the stress concentration factor and the thread pitch. Appropriately increasing the distance between the thread and shaft shoulder can reduce the stress concentration factor. The stress concentration factor calculated in this paper can be used to modify the S-N (Stress-fatigue life) curve of the shaft material, so as to improve the prediction accuracy of the pump shaft fatigue life. The influence law of each influence factor can provide optimization suggestions for the pump shaft structure.