SR100垂直摇臂式喷头摇臂有限元分析

针对垂直摇臂式喷头导流器几何结构及运动特性,研究了摇臂在运动过程中的受力及约束情况,并结合动力学理论计算公式,计算和分析了喷头在运动过程中载荷大小和约束情况.采用ANSYS Workbench软件,建立摇臂三维模型,对摇臂进行有限元模态分析、静力学分析及疲劳可靠性分析.通过有限元模态分析,得出各阶模态下摇臂的固有频率和振型,该摇臂的各阶振型主要表现为弯曲、扭曲及局部变形;当摇臂的工作频率小于41.785 Hz时,其振动以一阶振型为主.通过静力分析得出摇臂的应力分布情况,发现在摇臂安装导流器处存在较大的应力分布;通过对摇臂的疲劳分析,发现摇臂各部位安全系数差别很大,其最小值位于摇臂前端,为1.229 1,长期工作此处易发生裂纹或断裂.为提高摇臂的工作稳定性与可靠性,可以通过加强薄弱部位设计,或改进局部结构、提高材料的力学性能来实现.

Finite element analysis of arm of SR100 vertical impact sprinkler

The arm of a vertical impact sprinkler is one main part for bearing a load. The structure of the arm was simplified and the forces acting on it were calculated based on an analysis of the forces applied on the deflector in the sprinkler. Besides, the hydraulic force generated by a water jet impacting on the arm was figured out by using a theoretical analysis. Modal, static, and fatigue analyses for the arm were conducted by using finite element method on ANSYS Workbench. Eventually, the natural frequency and vibration mode of the arm at each modal are obtained, showing the vibration modes are mainly presented by bending, twisting and local deformations. When the arm works under the frequen-cy less than 41.785 Hz, its vibration modes are usually in the first order. A stress distribution in the arm is generated in the static analysis, and a stress concentration is found in the position where the deflector is installed. In the fatigue analysis, it is shown that the safety factor varies greatly across the arm and the minimum factor is found to be 1.229 1 in front end of the arm. This means that crack or fracture can occur easily in that portion in the arm in a long-term operation, and the strength of that portion should be strengthened. In order to improve the stability and reliability of the arm of sprinkler in operation, the local configuration with stress concentration in the arm may need to be redesigned or the arm may adopt a material with even stronger strength.