振型分解实施之前，先进行模态分析，模态分析的基本目的就是计算结构的固有

振型分解实施之前，先进行模态分析，模态分析的基本目的就是计算结构的固有频率和模态振型，ANSYS环境下的模态分析是一个线性分析，即在模态分析中只有线性行为是有效的，其过程为：<br>1）建立模型：在前处理中定义单元类型、单元属性、材料特性。<br>2）自振周期的计算：定义分析类型、施加载荷并求解自振频率。<br>3）扩展模态：将振型写入结果文件，以便后处理中观察振型。<br>4）观察求解结果：经过模态扩展后，模态分析结果被写入到结构分析的结果文件中，其中包括自振频率和已扩展的模态振型。

振型分解实施之前，先进行模态分析，模态分析的基本目的就是计算结构的固有频率和模态振型，ANSYS环境下的模态分析是一个线性分析，即在模态分析中只有线性行为是有效的，其过程为：<br>1）建立模型：在前处理中定义单元类型、单元属性、材料特性。<br>2）自振周期的计算：定义分析类型、施加载荷并求解自振频率。<br>3）扩展模态：将振型写入结果文件，以便后处理中观察振型。<br>4）观察求解结果：经过模态扩展后，模态分析结果被写入到结构分析的结果文件中，其中包括自振频率和已扩展的模态振型。

Before the implementation of mode decomposition, the modal analysis is carried out first. The basic purpose of modal analysis is to calculate the natural frequency and mode shape of the structure. The modal analysis under the environment of ANSYS is a linear analysis, that is to say, only the linear behavior is effective in the modal analysis. The process is as follows:<br>1) Build model: define cell type, cell attribute and material property in preprocessing.<br>2) Calculation of natural vibration period: define analysis type, apply load and solve natural vibration frequency.<br>3) Extended mode: write the mode shape to the result file, so as to observe the mode shape in the post-processing.<br>4) Observe the solution results: after the modal expansion, the modal analysis results are written into the result file of structural analysis, including the natural frequency and the expanded modal shape.<br>