Material and structural response of polymer-matrix fibre-reinforced composites

Abstract

This paper presents a pressure-dependent three-dimensional constitutive law to predict failure for laminated composites. The nonlinear constitutive response in shear and in the transverse and through-the-thickness directions, which is measured experimentally, is incorporated directly into the model. In addition, secant stiffnesses are dependent on the state of hydrostatic pressure and on the general state of strain. The failure criteria distinguish between matrix failure, fibre kinking and fibre tensile failure. In-situ strengths are used for matrix failure. Propagation of failure takes into consideration the fracture energy associated with each failure mode and, for matrix failure, the accumulation of cracks in the plies. A detailed discussion is undertaken of the mismatch between the available experimental data and the physical properties required to characterise the constitutive response up to final failure. The model is employed to make blind predictions of the triaxial failure envelopes and stress-strain curves of all 12 test cases provided by the organisers of the second World-Wide Failure Exercise.

Multi-scale damage modelling of 3D woven composites under uni-axial tension

“…According to the models developed during the second World-Wide Failure exercise [25,26], the theory developed by Pinho et al [27,28] was one of the three better theories among all twelve proposed models and can be easily implemented into Abaqus. Therefore this theory was adapted in this work to predict the failure behaviour of each component of the 3D composites.…”

“…Failure initiation The failure criterion developed by Pinho et al [27,28] de ned independent failure indices for di erent types of failure modes and also de ned the crack initiation state and propagation state. The pure polymer failure, matrix failure within the composites, and bre tensile failure criterion were included in the model.…”

“…The pure polymer failure, matrix failure within the composites, and bre tensile failure criterion were included in the model. The thick-embedded-ply matrix failure criterion developed in [27,28] was used in the unit cell model since the thickness of the tow (0.46 mm) is higher than the thickness of a typical lamina (0.125 mm). All materials in this model were assumed to have linear elastic behaviour before failure initiates, therefore the criterion set for linear elastic fracture was used.…”

“…T , S is L , and S is T are the in-situ transverse tensile strength, in-situ longitudinal shear strength, and in-situ transverse shear strength, which were calculated using Equation 8 [28]. The friction coe cients η T and η L account for the e ect of pressure on the fracture behaviour, and the values used by Pinho et al [28] (η T = 0.287, η L = 0.082) were used this paper.…”

“…The friction coe cients η T and η L account for the e ect of pressure on the fracture behaviour, and the values used by Pinho et al [28] (η T = 0.287, η L = 0.082) were used this paper.…”