COMPOSITES 2025

Mechanical properties of the hybrid Bouligand laminates and thin ply angle ply laminates with small angles

  • Yamada, Kohei (Industrial Technology Center of Fukui prefect)
  • Matsumoto, Hibiki (Kyoto University)
  • Yoshikawa, Ryoichi (Kyoto University)
  • Nishikawa, Masaaki (Kyoto University)

In session: CT - Thin Ply

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The thin ply prepregs that was originally developed in Industrial Technology Center of Fukui prefecture (ITCF) are attracting the attention from the point of view of improvement of the mechanical properties that results from the suppressive effect of the first ply failure. The advantage of applying thin ply prepregs to composite structure is not only the improvement of mechanical properties, but also the expansion of design freedom. For example, when designing structural materials with the same thickness, it is possible to insert more plies with various fiber orientations by use of thin ply materials. Utilizing these features, many mechanical properties not ever seen in CFRP with a configuration of 45° quasi-isotropic (QUAD) have been confirmed. For example, Fuller et al. revealed thin ply angle ply laminates with several angles between 15° and 45° exhibited pseudo-ductility under tensile loadings due to fiber rotation [1]. Besides, there have been many studies to reproduce CFRP structures that mimic living organisms, a representative example is the Bouligand structure that mimics helicoidal layup of dactyl clubs. Previous studies confirmed that Bouligand structure using thin ply reduced delamination areas and defused sub-critical damage during impact loading [2, 3]. In this study, a hybrid laminates consisting of Bouligand structure and QUAD was proposed. Impact tests of the hybrid laminates indicated that a straight propagation of the crack was suppressed, leading to the effective reduction of the projected delamination area. In addition, the compression properties of thin ply angle ply laminates with small angles (5, 10, 15°) were also experimentally investigated. As a result, pseudo ductility which had previously been confirmed under tensile loading was shown also under the compressive loading attributed to the high tolerance to fiber rotation by use of thin ply prepreg.