Compressive failure mechanisms in unidirectional fiber reinforced polymer composites with embedded wrinkles

Abstract

The present study examines how wrinkles affect a composite material’s compressive failure behavior. Uni-directional carbon fiber-reinforced polymer (UD-CFRP) composites with artificially induced wrinkles were fabricated by placing laminate strips in specific positions. The geometry and placement of these strips were varied, resulting in 18 different wrinkle configurations. Through extensive experimental testing, it was observed that the compressive strength decreased significantly, ranging from 20% to 73%, depending on the specific wrinkle configuration. The experimental results were found to align well with existing analytical models. Additionally, the study examined how the wrinkle characteristics affected the final kink bandwidth, angle, and inclination. Fractographic studies on the failed specimens revealed various damage modes at different length scales, including kinking, delamination, buckle delamination, crushing, fiber pullout, matrix cracking/failure, and fiber failure. Based on these findings, it is emphasized that the geometry of the wrinkles and the aforementioned damage modes at different length scales must be accounted for while developing a numerical model to predict the compressive behavior of the composite accurately.