Optical Tracking
Non-contact strain measurement utilizes high-resolution cameras to track surface deformation during mechanical testing. By using digital image correlation, researchers can map the local strain fields across the surface of a fabric under tension. This optical technique compares digital images captured before and after deformation.
Measurement Principle
Algorithms track a random speckle pattern applied to the surface of the specimen to detect displacements of individual pixels. Through digital image correlation, the software calculates both axial and shear strain components across the entire test area.
Technical Application
Woven, knitted, and non-woven structures exhibit highly localized strain variations due to their internal architecture. Applying digital image correlation to textile testing reveals strain concentrations near seams, holes, and joints. This information helps engineers design stronger protective garments.
The cameras can be run at high speed to capture dynamic strain during tear tests. This capability provides a detailed view of the progression of failure in real time.
Material Characterization
Mechanical properties of anisotropic materials are difficult to measure using traditional extensometers. The application of digital image correlation overcomes this limitation by providing continuous, non-contact measurements. This technique is essential for validating numerical models of composite fabrics.
It offers a clear picture of the behavior of the fabric under stress.
