考虑卡箍预紧状态的空间管路3维有限元建模

3D Finite Element Modeling of Spatial Pipeline Considering the Pre-tightening State of Clamps

为了准确分析管路系统的振动应力,在合理引入卡箍预紧状态的前提下,提出了一种空间管路3维有限元建模方法,创建了管路3维实体有限元模型。通过分析上下箍带对管路的夹紧力,确定了模拟卡箍力学特性的弹簧单元刚度值分布规律;卡箍不同位置处的水平和竖直方向的刚度存在比例关系,且比例关系与位置角和方向有关;给出了用实体单元并引入上述卡箍约束的有限元建模流程,其中每个卡箍用2个同面并按照节点分布的弹簧组来模拟,真实地反映了管路的几何特征和卡箍的约束状态,能够适应管路系统动应力求解的需求;搭建了对应模态和谐响应分析的试验装置,并将试验结果和仿真结果进行了对比。结果表明:相对于管单元,采用考虑卡箍预紧的管路系统3维有限元建模方法得到的固有频率和应力响应结果更贴近实测结果,仿真计算与实测的振动应力偏差小于20%。

To accurately analyze the vibration stress of the pipeline system,a 3D finite element modeling method of spatial pipeline was proposed and 3D solid finite element models of pipelines were created under the premise of reasonably introduction of the pre-tightening state of the clamps.The stiffness distribution of the spring elements used to simulate the mechanical characteristics of the clamp was determined by analyzing the clamping force of the upper and lower metal belts of the clamp on the pipeline.There is a proportional relationship between the horizontal and vertical stiffness at different positions of the clamp,and the proportional relationship was related to the position angle and direction.A finite element modeling process with solid elements and the clamp constraints is presented,in which each clamp is simulated by two coplanar spring groups distributed according to the nodes.This modeling method can truly reflect the geometric characteristics of the pipeline and the constraint state of the clamp and can meet the needs of solving the dynamic stress of the pipeline system.The corresponding experimental device for modal and harmonic response analysis was built,and the experimental results were compared with the simulation results.The results show that the natural frequency and stress response results obtained by the proposed 3D finite element modeling method of the pipeline system considering the pre-tightening state of the clamp are closer to the measured results compared with the pipe element,and the deviation between the simulated and the measured vibration stress is less than 20%.