Hylec Controls presents video extensometers from leading European
manufacturer, Mercury designed for non contact strain measurement.
Various developments in computers and digital cameras, together with
advances in digital image processing, have now made video extensometers an
affordable option for strain measurement. Mercury supplies to both UTM
manufacturers and the retrofit market.
Mercury’s video extensometers use the principle of digital image
correlation (DIC) to measure strain on all sorts of patterned materials without
the need for gauge marks. For reflective materials or transparent materials, the
technique can be used if the sample is first sprayed with reflective paint or has
grid or gauge marks attached to the sample.
The DIC technique measures the strain between successive image frames so
changes in pattern over the period of the test can occur without altering the
ability of the system to measure the strain. DIC is particularly useful when
measuring strain in a furnace.
The DIC system can measure strains with a resolution of down to 0.1
micron and at sample rates of up to 4KHz, making such systems suitable for both
static and dynamic testing. One to three cameras can be used to improve
resolution or measure strains in all three axes.
An analogue output with the ability to interface with the machine’s
controller is provided to enable the DIC system to be used with existing UTMs.