The flexural–torsional vibration behavior of unrestrained and braced thin-walled beams is investigated by experimental and finite elements approaches. In the experimental part, tests in free and forced vibrations of thin walled beams with arbitrary sections are analyzed. By the help of an instrumental hammer test and a shaker machine, the natural frequencies and the response spectra of the beams are extracted in the range 1–400[Formula: see text]Hz. Beam displacements are measured by some accelerometer transducers. The behavior is also investigated by the finite element method. In mesh process, 3D beams are adopted and an additional DOF is affected to the warping. The model is implemented in a home-made model. The numerical and experimental results are compared to numerical simulations of a commercial code. Test results and numerical simulations of the present model agree well. The model seems to be accurate especially in the presence of higher vibration and coupled modes.

中文翻译：

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薄壁梁自由和受迫振动的数值和实验分析

通过实验和有限元方法研究了无约束和支撑薄壁梁的弯扭振动行为。在实验部分，分析了任意截面薄壁梁的自由和受迫振动试验。借助仪器锤试验和振动机，在1-400[公式：见正文]Hz范围内提取了梁的固有频率和响应谱。光束位移由一些加速度传感器测量。该行为也通过有限元方法进行研究。在网格过程中，采用了 3D 梁，并且额外的自由度影响了翘曲。该模型以自制模型实现。数值和实验结果与商业代码的数值模拟进行了比较。本模型的试验结果与数值模拟吻合良好。该模型似乎是准确的，尤其是在存在较高振动和耦合模式的情况下。