The effectiveness of shearography and digital image correlation for the study of creep in elastomers

In this paper, authors present a study of the application of speckle shearing interferometry (shearography) and digital image correlation to measure viscoelasticity in terms of creep compliance of elastomeric materials. The creep tests were performed using two different elastomers (neoprene and EPDM) by applying a constant tensile stress to a specimen during 3 h. First, a shearography setup was implemented to measure directly the in-plane strains produced in the specimens and thus determining creep strains. Secondly, digital image correlation was also used to measure the creep strains in similar creep tests. The results obtained were compared each other to see the effectiveness of each measurement technique for the assessment of this property. It was demonstrated that these techniques can be potentially and successfully applied to the creep analysis of these kind of materials. Moreover, advantages and drawbacks of both measurement methods are discussed.