CRISTIAN DUDESCU, ADRIAN BOTEAN, MIHAIL HARDAU THERMAL EXPANSION COEFFICIENT DETERMINATION OF POLYMERIC MATERIALS USING DIGITAL IMAGE CORRELATION Applications of digital image correlation (DIC) method to material characterisation has been proven to be a powerful tool for deformations and strain analysis and found widespread use and acceptance in the field of experimental mechanics. This paper describes the potential, accuracy and limitations of a commercial DIC system to full-field, real-time characterisation of the coefficient of thermal expansion (CTE) of polymeric materials. The topics such as strain calculation procedure and influence of a small rigid body rotation were theoretically described and experimentally verified. A series of measurements was carried out to determine the CTE polypropylene (PP) and polyvinylchloride (PVC) commercial plastics. To check the feasibility of the method an aluminium sample was initially analysed. The measuring set-up developed includes a simple heating device, thermal sensors and a thermo-camera for real-time temperature measurement and monitoring of the sample and a 3D-DIC measuring system. The results revealed that the DIC can be a reliable tool for thermal deformations measurement especially suitable for polymeric materials with a higher CTE.
Keywords: digital image correlation, thermal strains, polymeric materials