Strain Signal Conditioning


Whether the stress is present in the automotive, architecture or aerospace sectors, precise understanding of strain signals is critical
Applications include manufacturing, process control, research laboratories, civil engineering and construction/architecture

WHAT IS STRAIN SIGNAL CONDITIONING?

The measurement of strain using resistive elements is a well established technique. An electrical resistance strain gauge consists of a conductor in the form of a resistance element attached to a thin insulating backing. To make a measurement, the strain gauge must be bonded to the component or structure under test. Since the strains experienced in most structures and components are small (μm/m), so are the resulting resistance changes in the strain gauge (μohms/ohm). To measure these very small changes, a Wheatstone Bridge is used.

In an application where the direction of principal strain is known, a single gauge with its axis lined up in this direction can be bonded to the structure to form one arm of the Wheatstone Bridge, the remaining three arms being provided by the measuring equipment. This single active gauge arrangement is known as a quarter bridge. If the principal strain direction is not known, a gauge configuration known as a rosette must be used. A rosette consists of a number of independent gauge grids – normally three – mounted on a common backing. Taking readings from a strain gauge involves the measurement of very small changes of resistance, therefore a suitable signal conditioning system is required.

Fylde also offer Dynamic Strain Measurement using the constant current system. This measures the variation of strain with time and disregards the static strain or very slowly varying strain. The constant current system uses a precise and stable constant current and provides excellent signal-to-noise ratio. This system avoids the need for bridge completions and balance required by bridge transducers. It also allows single element gauges to be connected using only a two wire twisted pair connection instead of the usual 3 wire connection.

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WHAT IS STRAIN SIGNAL CONDITIONING?

WHAT DO YOU HAVE TO CONSIDER WHEN DOING STRAIN SIGNAL CONDITIONING?

  • 1:

    Bridge transducer (static) or constant current (dynamic) systems? Fylde offers both, talk to a member of our team if you are unsure which is best for you.
  • 2:

    Do you know the direction of strain? If so you can use a quarter bridge. If not, then a rosette gauge configuration must be used.
  • 3:

    Think about the material you’re using. Strain gauges are essentially limited by their elastic behaviour. With some knowledge of the limit of stretch, probably of material the gauge is bonded to, you can select a suitable strain gauge.
  • 4:

    What is the environment? You might have to locate the electronic equipment at some distance from the gauge location, which will influence the choice of signal conditioning.
  • 5:

    Many other factors can also influence your choice of signal conditioning – cost, connectors, power supply, space constraints, bandwidth, control, data acquisition, data analysis, long term stability… and many more. You might want to discuss these with our team.

WHAT FYLDE PRODUCTS ARE AVAILABLE?

A wide variety of bridge and dynamic strain amplifiers can be found in Fylde’s various technology ranges.
  • FE-366-TA (Micro-Analog 2) is the most cost effective strain conditioner. (Static strain, and manually set up using on board jumpers.) Can be combined with Micro-Analog 2 Data Acquisition.
  • FE-579-TA (5-Series) is a fully featured bridge amplifier with front panel controls and remote control.
  • FE-537-SGA - (5-Series) is a dynamic strain amplifier with front panel controls.
  • FE-379-TA – Traditional analogue amplifier with excellent stability.
  • FE-H379-TA – Traditional analogue amplifier with very high bandwidth (> 500 kHz) for special applications.

Browse the 5-Series and Micro Analog 2 ranges for general-purpose bridge and dynamic strain amplifiers. Consider our range of additional products for amplifiers that are suitable for more specific and niche applications.

Browse our technologies and find download technical data sheets.

Fylde Electronic Laboratories Ltd
49/51 Fylde Road, Preston, Lancashire, UK PR1 2XQ
T: +44 (0)1772 257560
E: sales@fylde.com

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