Impact Test with Software Trigger (DAQmx)

This VI performs a triggered acquisiton from two channels on the same device. The first channel should use a sensor mounted on an impact hammer. The second channel should use an accelerometer mounted on the structure under test.

The data from each channel is windowed and the frequency response is computed. The results of the frequency response measurement are displayed as magnitude and phase. The coherence is also graphed to evaluate the validity of the measured frequency response.

Requirements

Filename: impacttest_wswtrg.zip

Software Requirements

Application Software: LabVIEW Base Development System 8.0
Toolkits and Add-Ons: LabVIEW Sound and Vibration Toolset 4.0
Language(s): LabVIEW

Hardware Requirements

Hardware Group: Dynamic Signal Analyzers (DSA)
Hardware Model: USB-9233
Driver: NI-DAQmx 7.5

Reader Comments | Submit a comment »

Preferable for impact tests to Analog Level Trigger with Pre-Trigger Samples
I found this VI incredibly helpful, as I had started developing an impact test rig using ContAcq&Graph Voltage-Analog SW Trigger. The problem with using that was that the trigger position within the continuously acquired buffer was never fixed, meaning that occasionally you could miss an entire impact's data. Simply increasing the buffer size wouldn't have helped, as you could still receive a trigger at the end of the buffer. This VI takes a slightly different approach, meaning that it does not suffer from this problem and is able to capture the same number of datapoints each time.
- Tim Hoult, Imperial College. timothy.hoult@imperial.ac.uk - Aug 24, 2007