利用不完备实测模态修正杆系结构约束边界条件

该文针对杆系结构约束边界条件模型修正问题进行了研究。通过边界单元刚度矩阵的建立,将现有的子结构校正因子修正方法发展到边界条件的修正中。通过一种迭代的修正过程,仅用有限的低阶实测频率就可以实现对边界条件的修正。另外,该文提出了一种分步式整体修正方法,利用低阶不完备实测模态,实现对边界和上部结构的整体修正,有效地避免了修正方程组的病态问题。论文首先通过对悬臂梁有限元模型进行数值研究,验证了边界条件修正方法和分步式整体修正方法的正确性。最后通过悬臂梁物理模型试验,验证了方法的可行性。

MODEL UPDATING FOR CONSTRAINT BOUNDARY CONDITIONS OF MEMBER STRUCTURES USING INCOMPLETE MEASURED MODES

The constraint boundary condition model updating a member structure was studied in this paper.Through building the boundary element stiffness matrixes,the present substructure correction factor updating method was extent to the boundary conditions.With an iterative procedure,the boundary conditions can be updated based on only a few measured modal frequencies.And also,a two-step method is proposed to update the whole structure(including the boundary and the superstructure) using lower incomplete measured modes,which can avoid the ill-condition problem.Numerical examples based on finite element models associated with a cantilever beam are chosen to investigate the accuracy of the proposed boundary conditions updating method and the two-step method.Furthermore,an experiment study associated with a steel cantilever beam is also conducted to examine the proposed methods.