Taking the Strain - a Dynamic Strain Acquisition Solution

A complete 32 channel 100KHz bandwidth dynamic strain acquisition solution.

High speed acquisition is essential for good shock response (transient vibration) measurement. This system provides strain gauge power and full bridge completion as well as high performance data acquisition, recording and analysis for use on-board Navy ships.

Several systems are used for even higher channel counts. A central trigger (TTL) is supplied to all systems for synchronisation.

The solution consists of a VXI based system supplied by VXI Technology (VT). It includes two VT1432A cards (32 channels) and one VT1529B remote strain gauge front-end.

The sensors used are piezo-resistive accelerometers (full bridges) specified in mV/g.

The VT1529B is controlled from a VT1422A VXI card together with a VT1539A SCP.

Two E3644A power supplies (Agilent) are also included to provide up to two different bridge excitation voltages.

The 100KHz bandwidth VT1529B unit provides all the circuitry needed for bridge measurements, no additional signal conditioning is required. This includes:

  • bridge completion
  • bridge excitation via external power supplies
  • bridge sensing
  • bridge excitation sensing
  • offset/shunt calibration etc.

Data Acquisition is by VT1432A´s connected to the dynamic outputs (100 KHz bandwidth) of the VT1529B to measure the bridge voltages. They are triggered on one of their external trigger inputs.

The additional external power supplies which are routed through the VT1529B box to the strain gauges (bridges) providing ample power (current) for very long sensor leads (100 meters +). Insufficient power is a common shortcoming of many systems that rely on build-in bridge excitation supply per channel.

Since the VT1432A´s can be used in AC coupled mode this eliminates the requirement for DC offset calibration and provide excellent performance to the 1Hz cut-off frequency. At the higher end the VT1432B option provides sampling frequencies to 102kHz on every channel. Other cards are available to 200kS/s on every channel.

SmartOffice Throughput Wizard is used for acquiring data and recording directly to disc. Further processing of the data is done with SmartOffice, Shock Response analysis, and data can also be exported in a variety of industry standard formats for use in other packages including Matlab and MTS I-DEAS.

Go back