Development of a Low-cost Digital Image Correlation System to Evaluate the Behavior of Polymers at Large Deformation

Abstract

Among the main optical methods digital image correlation (DIC) can be highlighted. Although DIC development is relatively recent, the advantages offered by this method make it equally competitive with other classical optical techniques that suffer from intrinsic limitation. The need for global field measurements is especially true in situations where the loading conditions create a heterogeneous strain field. Thus, DIC has been presented as the most adequate measurement technique for studying the behavior of polymeric materials exposed to large deformation. As a consequence of their inherent characteristics, polymers have been increasingly used in engineering applications, especially thermoplastics. Allied to its low density, which provides a considerable weight reduction and an increase of efficiency in many applications, polymers also have easy processability and good mechanical properties. Thus, a precise knowledge of polymers behavior is needed in order to improve their use capabilities. Despite DIC consistent evolution, especially in the image acquisition system, it is still an inaccessible optical measurement technique due to the high price of digital processing and image correlation software. Therefore, the present work aims to develop a low-cost digital image correlation (DIC) system to evaluate thermoplastic behavior at large deformations. In order to improve the discussion three different types of polymers were tested: high density polyethylene (PE-HD), polypropylene (PP) and polyvinyl chloride (PVC).