The modal testing experiment presented here is performed by a medical system manufacturer using ModalVIEW software and National Instruments DSA hardware as the modal testing and analysis tool. The analysis result is used to verify noise and vibration performance of their structure design.

Experiment scenario

The testing object is a CT scanner structure:

The structure of CT scanner is excited by impact hammer, and the vibraiton is measured using tri-axial accelerometer. ModalVIEW modal analysis software provides FRF measurement and advanced modal analysis method based on mode stabilization diagram to extract modes from FRF data. National Instruments 24-bit module USB-4431 is used to guarantee the accurate measurement of weak vibration signal of measured points far away from excitation point.  

System configuration

In this modal testing experiment, the following software and hardware are used：

1．ModalVIEW R2 Software.

2．NI DSA System (USB-4431)

3．Tri-axial accelerometer (PCB 356A26).

4．Impact Hammer (PCB 086C01) .

Structure Modeling

3D model of CT scanner structure is created from its photo. ModalVIEW helps to quickly create 2D grid from manually selected nodes on photo.

Analysis results

Modal analysis for the structure is finished with ModalVIEW’s advanced mode estimation method based on mode stabilization diagram from 149 measured FRF data. Part of the mode shapes are displayed as following :

Download this application note in PDF format