基于非线性声弹性效应的输电铁塔螺栓预紧力预测数值分析

Numerical Analysis of Bolt Preload of Transmission Towers Based on Nonlinear Acoustoelasticity Effect

基于发展输电铁塔螺栓结构健康监测技术的现实需求,利用非线性声弹性效应,建立了输电铁塔螺栓的有限元模型,并发展了一种基于多物理场耦合的数值迭代算法。首先,考虑输电铁塔螺栓的几何构形特征,建立了预紧力作用下螺栓结构的轴对称二维有限元模型,并考虑预紧力作用下超声纵波的非线性声弹性效应,采用考虑三阶声弹性效应的默纳汉超弹性材料,实现螺栓结构的应力-应变场和声场的耦合求解分析,并进行了试验验证。计算结果表明:预紧力和夹持长度对螺栓结构内部的应力场分布状态有着显著的影响,同时预紧力导致的波速变化和螺栓形变对超声纵波的渡越时间有着双重影响。所建模型和分析方法为基于非线性声弹性效应的螺栓预紧力测量技术提供了数值模拟分析平台,可为相关试验研究和仪器研制工作提供技术指导。

Based on the practical needs for developing the structural health monitoring technologies of transmission tower bolted structures,a finite element model of transmission tower bolt is established based on the nonlinear acoustoelastic effect,and a multiphysics coupling numerical iterative algorithm is proposed.Firstly,based on the geometric configuration characteristics of the transmission tower bolts,a two-dimensional axis-symmetric finite element model is established.and then the Murnaghan hyperelastic material that considers the third-order acoustoelastic effect is used to realize the coupling solution analysis of the stress-strain field and the acoustic field of the bolt.Finally,the proposed numerical model and the iteration method is validated through experiment.The results show that the preload and the clamping length have a significant effect on the stress field distribution within the bolt structure,and the wave velocity variation and bolt deformation caused by the bolt preload have a dual impact on the time of flight of the ultrasonic longitudinal wave.The model and numerical method proposed in this paper can provide a numerical simulation platform for bolt preload measurement based on the nonlinear acoustoelastic effect,and can also provide a technical guidance for related experimental research and instrument development.