基于理论仿真和实验的两端固定梁模态测试方法

Modal Testing Method of Fixed Beams at Both Ends Based on Theory, Simulation and Experiment

基于欧拉-伯努利梁理论,得到两端固定梁自由振动的振型函数。通过数值计算得出实验用的两端固定梁前五阶振型的节点位置及其与梁长的比值。考虑传感器对两端固定梁固有频率的影响,建立梁-传感器模型进行仿真分析并得出两端固定梁前五阶固有频率。基于节点位置和测点位置,在实验中选择参考点。将具体实验的结果与梁-传感器仿真模型结果进行对比,通过前五阶固有频率的误差分析,发现仿真分析结果与实验结果误差最高为2.92%。研究完整地叙述了两端固定梁的模态测试流程,可为工程技术人员的模态测试起一定的指导作用。

Based on Euler-Bernoulli beam theory,the modal shape function of the beam in the free vibration state are obtained.The joint position of the first five modes of the fixed beam at both ends and its ratio to the length of the beam are obtained by numerical calculation.Considering the influence of sensor on the natural frequency of two ends fixed beam,a beam-sensor model is established to obtain the first five natural frequencies of two ends fixed beam.the reference point of modal experiment is chosen in experiment based on the node position and measuring point position.Comparing the results of beam-sensor simulation mode with specific experiments,it is found that the maximum of these two results error is 2.92%by error analysis of first five order natural frequencies.The research provide a theoretical basis for engineering technicians to determine the location of nodes in the modal experiment,and give the selected method of exciting point in the specific experiment.