Use of Image Analysis in Determination of Strain Distribution During Geosynthetic Tensile Testing

Determining the deformation response of geosynthetics under load is important in developing an in-depth understanding of the engineering behavior of these materials. Current strain determination methods employed as part of tensile tests mostly assume that the strain is uniform throughout the specimen and, hence, are incapable of determining local strains. Geosynthetics have occasionally been instrumented with strain gauges and extensometers; however, these direct contact methods have limitations in fully defining strain distributions in a test specimen. Recent technological advancements in image analysis offer great potential for a more accurate and noncontact method of determining strains. An image-based particle tracking method was used to define the strain distribution in various geosynthetics during wide-width tensile testing. The method used a block-based matching algorithm functioning under LABVIEW. The measured gross strain values were compared to those determined from strain gauges and extensometers. The strain values determined by these methods were comparable to the image-based ones, and the absolute value of the difference was less than 10% for the geosynthetics tested. Furthermore, the image-based analysis was effective in also determining the local strains. DOI: 10.1061/~ASCE!0887-3801~2004!18:1~65! CE Database subject headings: Image analysis; Strain distribution; Deformation; Geosynthetics.