TESTING: Non-Contact Video Extensometer For Tensile Testing Of Plastics

Imetrum's Video-Gauge is claimed to be the first non-contact extensometer that can test tensile properties pf plastics to exact ASTM and ISO requirements.

U.K.’ Imetrum (North American distributor is Respec, Rapid City, SD) has launched what is reportedly the first non-contact video extensometer capable of achieving the exacting requirements of ASTMD638 and ISO527-1 equivalent for measuring tensile properties of plastics.

            Following rigorous, independent testing, Video Gauge has been shown to be capable of accurate determination of the tensile modulus be measuring a change of gauge length within accuracy of 1% of the relevant value. In tests, Imetrum was able to achieve between 0.2µm to 0.3µm (7.87 x 10(6)  to 1.18 x 10(5)) for all gauge lengths using the same camera and lens combination—over three times the accuracy required by ASTMD638/ISO527 for 50mm (1.97 in.) gauge length.  

            Designed for use with tensile testing machines, the new system comprises a controller with sophisticated Video Gauge software, one or more high-resolution digital video cameras and an appropriate lens for the application. Also included is a voltage output module for interfacing with traditional strain channels, lighting, a tripod, and a rugged case for storage and transport. One of its key advantages over clip-on extensometer methods is that the Video Gauge avoids the problem of knife edge slippage where the knife edges can potentially cur into a specimen and induce a failure point. This system can complete a test through modulus and on to failure, eliminating the need to stop the test and remove clip-on extensometers.