Mesoscale modelling of tensile response and damage evolution in natural fibre reinforced laminates

Abstract

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Hybrid micromechanical-phenomenological modelling of anisotropic damage and anelasticity induced by micro-cracks in unidirectional composites

“…Due to the micro-structure arrangement the micro-crack are forced to propagate in a plane parallel to the fibre direction x 1 . Moreover, if the material is mainly loaded in plane stress (plane x 1 , x 2 ) as it is often the case, then the propagation plane of the micro-cracks can be considered as being perpendicular to the second direction x 2 and consequently always oriented in the same plane Damage in such type of materials generally brings about permanent strains due to the micro-cracks non-closure and the resultant sliding with friction (Le Dantec, 1989;Ladevèze and Le Dantec, 1992;Boubakar et al, 2002Boubakar et al, , 2003Mahboob et al, 2017). In the present model, these damage induced permanent strains are phenomenologically described by an anelastic strain tensor denoted by ε s .…”

“…Classically, in most of the continuum damage models for unidirectional composite (Le Dantec, 1989;Ladevèze and Le Dantec, 1992;Ladevèze, 1992;Allix et al, 1994;Boubakar et al, 2002Boubakar et al, , 2003Mahboob et al, 2017), the damage variables are driven by a criterion based on their associated variables, namely the energy density releases. In the present formulation, such a control would be inappropriate, since the growth of oriented micro-cracks is only generated under a certain type of stress state, namely when σ 22 and σ 12 are involved.…”

“…Classically, in most of the CDM-based models for unidirectional composites (Le Dantec, 1989;Ladevèze and Le Dantec, 1992;Ladevèze, 1992;Allix et al, 1994;Boubakar et al, 2002Boubakar et al, , 2003Mahboob et al, 2017), the anelastic mechanisms are formulated in a similar manner as plasticity, where the anelastic strains are governed by a yield criterion written in the effective stress space (Lemaitre and Chaboche, 1990;Lemaitre and Desmorat, 2005).…”

“…Compared to classical CDM models for unidirectional composites (Le Dantec, 1989;Ladevèze and Le Dantec, 1992;Ladevèze, 1992;Allix et al, 1994;Boubakar et al, 2002Boubakar et al, , 2003Mahboob et al, 2017), the present modelling strategy leads to a reduced number of parameters with a certain ease regarding their identification. Moreover, the hybrid micromechanicalphenomenological formulation brings a physical basis to the model, while its practical use remains as computationally efficient as any purely phenomenological approach.…”

“…Initially developed in the context of isotropic material response, the CDM was adapted to the anisotropic case of unidirectional composites (Le Dantec, 1989;Ladevèze and Le Dantec, 1992;Ladevèze, 1992;Allix et al, 1994;Boubakar et al, 2002Boubakar et al, , 2003Mahboob et al, 2017). The effects of micro-cracks are usually accounted through the introduction of several damage state variables that directly define the reduction of the material stiffness.…”