A finite strain approach to model intralaminar failure mechanisms in fibre-reinforced polymers

  • Rodrigues Lopes, Igor André (INEGI)
  • Danzi, Federico (INEGI)
  • Arteiro, Albertino (FEUP)
  • Andrade Pires, Francisco Manuel (FEUP)
  • Camanho, Pedro (FEUP)

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Damage and fracture models typically employed to predict the progressive failure of fibre-reinforced composites are usually developed under the small strain assumption. Even though brittle fracture is often observed in carbon-fibre/epoxy systems, in some situations the material may undergo deformations that do not comply with such assumption anymore. That is the case of load cases leading to failure modes controlled by the matrix. Additionally, new generations of fibre-reinforced thermoplastics are prone to exhibit a more ductile response prior to failure, involving large deformations. As a matter of fact, the importance of accounting for finite strains in the constitutive equations employed to model the mechanical behaviour of composite materials, up to their failure, has been discussed recently [1]. In this contribution, a finite strain extension of the smeared crack model introduced in [2] is proposed to deal with transverse matrix cracking. It relies on an invariant-based criterion to predict the onset of transverse damage, which activates a cohesive crack formulation embedded in the continuum description. The deformation gradient decomposition proposed in [3] is enhanced, based on homogenisation considerations, to obtain a more objective kinematic description. Re-orientation of the fracture plane is naturally considered by establishing the local equilibrium problem in the reference configuration, and an appropriate extrinsic mixed mode cohesive law is devised to deal with non-monotonic loading. For longitudinal failure, a continuum damage model formulated in terms of the Green-Lagrange strain tensor is employed. The resulting model is implemented in a user-defined Abaqus routine, and representative numerical examples are shown to illustrate its predictive capabilities. REFERENCES [1] Tijs, B.H.A.H., Dávila, C.G., Turon, A. and Bisagni, C. (2023). The importance of accounting for large deformation in continuum damage models in predicting matrix failure of composites. Composites Part A: Applied Science and Manufacturing, 164, 107263. [2] Camanho, P. P., Bessa, M. A., Catalanotti, G., Vogler, M., and Rolfes, R. (2013). Modeling the inelastic deformation and fracture of polymer composites-Part II: Smeared crack model. Mechanics of Materials, 59, 36–49. [3] Leone, F. A. (2015). Deformation gradient tensor decomposition for representing matrix cracks in fiber-reinforced materials. Composites Part A: Applied Science and Manufacturing, 76, 334–341.