Comparison between 3-point bending and torsion methods for determining the viscoelastic properties of fiber-reinforced epoxy. (May 2020) - Huayamares, Sebastian
Abstract: Dynamic mechanical analysis is a technique used to determine the viscoelastic properties of polymers and their composites. The storage modulus, loss modulus and loss factor in correlation with the glass transition temperature can be detected by several means. In this study, these properties are determined using a dynamic mechanical analyzer in 3-point bending mode, as well as a rheometer in torsion mode. The materials under consideration are a unidirectional glass fiber-reinforced epoxy, a quasi-isotropic carbon fiber-reinforced epoxy and a quasi-isotropic glass fiber-reinforced epoxy. The results of each method and material are presented and the advantages and limitations of each method are discussed. 3-point bending proved to be more suitable to detect the effect of fiber orientation for unidirectional fiber-reinforced epoxy but requires careful control of sample dimensions for accuracy. Torsion, on the other hand, gave consistent measurements for samples of varying lengths, proving to be a suitable method if materials are scarce and limited. Highlights: Guide for FRP quality control. Guide for seleting 3-point bending or torsion methods for determining the viscoelastic properties of FRP. Torsion method is unable to track measure the effect of fiber orientation in FRP. 3-point bending method is sensitive to sample dimensional accuracy.