在“自由-自由”边界条件下测试白车身模态参数：在白车身上安装传感器、连接测试系统，布置129个三向加速度传感器为响应点，并建立几何模型。用激振器激励响应点，采集激励力与加速度响应信号，处理获取频率响应函数（FRF）数据。通过系统参数识别，从测得的输入/输出数据中确定样件的振动特性，得到固有频率（Hz）、阻尼比（%）及振型描述。

Test the modal parameters of the white body under the "free-free" boundary conditions: install sensors on the white body, connect the test system, arrange 129 three-way acceleration sensors as response points, and establish a geometric model. Use a vibration exciter to excite the response point, collect the excitation force and acceleration response signals, and process and obtain the frequency response function (FRF) data. Through system parameter identification, the vibration characteristics of the sample are determined from the measured input/output data, and the natural frequency (Hz), damping ratio (%) and mode description are obtained.