The problem of model order reduction and dynamic characteristic analysis of the bolted flange structure with free-free boundary conditions is studied by proposing a novel simplified modeling method. The proposed simplified modeling method is able to reduce the finite element model of the linear components through free-interface mode synthesis method and condense the number of degree-of-freedom of the joint interface through coordinate condensation, which can fix the model size not to increase with the number of bolts and greatly reduce the computational cost. Rigid-body mode elimination is also considered to further reduce the order of the integrated dynamic equation and avoid the problem of computational instability in the proposed simplified modeling method. An experimental bolted flange structure with free-free boundary conditions is built and the corresponding modal testing is carried out to verify the accuracy of the proposed simplified modeling method. Comparative results of modal testing and simulation indicate that gravity leads to unequal bending frequencies of the same order in X and Y directions, which also proves that the proposed simplified modeling method is able to analyze the dynamic characteristic of the bolted flange structure with free-free boundary conditions.

通过提出一种新的简化建模方法，研究了具有自由边界条件的螺栓法兰结构的模型降阶和动力特性分析问题。所提出的简化建模方法能够通过自由界面模态合成方法减少线性部件的有限元模型，并通过坐标压缩来压缩关节界面的自由度数，从而可以固定模型尺寸而不是随着螺栓数量的增加，大大降低了计算成本。还考虑了刚体模式消除，以进一步降低集成动力学方程的阶数，避免所提出的简化建模方法中的计算不稳定问题。建立了具有自由边界条件的实验螺栓法兰结构，并进行了相应的模态试验，以验证所提出的简化建模方法的准确性。模态试验与仿真对比结果表明，重力导致X、Y方向同阶弯曲频率不等，这也证明了所提出的简化建模方法能够分析具有自由自由度的螺栓法兰结构的动态特性。边界条件。