Adhesive polyvinyl chloride coatings for quantitative strain measurement in composite materials

A non-contact method is proposed to measure the strains on the surface of carbon fiber/epoxy composite materials using adhesive polyvinyl chloride (commonly called vinyl) coatings. Specimen preparation in digital image correlation methods yields inconsistent results due to the variability in the patterning procedure. The utility of this approach is the ability to apply computer generated randomized patterns on vinyl sheets that can be mechanically applied to the composite structure under inspection. Experimentally obtained strain values are compared to p-version finite element simulations of notched coupons showing a disparity in the correlation highly dependent on the properties of the constituents.