Three-dimensional nonlinear constitutive model for composites

Mandel, Ulrich; Taubert, Robin; Hinterhölzl, Roland

doi:10.1016/j.compstruct.2016.01.080

Cited by 18 publications

(10 citation statements)

References 18 publications

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“…The shear stress obtained from compression tests is slightly higher than that from tension tests. This may indicate the dependence of in-plane shear response upon hydrostatic pressure [18,19] and thus caused different deformation and failure mechanisms, as discussed in Section4.1. When comparing the results against constitutive models readily available in commercial simulation packages, it is clear that not taking into account the rotation of fibre not only results in an increase in the apparent stress calculated using small strain theory, but it also causes the apparent reduction in stiffness in the original fibre orientation and a change in the in-plane distribution of stresses.…”

Section: Shear Response With Correction Of Fibre Rotation Effectmentioning

confidence: 96%

Effect of strain rate and fibre rotation on the in-plane shear response of ±45° laminates in tension and compression tests

Cui

Thomson

Pellegrino

et al. 2016

Composites Science and Technology

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This work focuses on the effect of strain rate and fibre rotation on the in-plane shear properties of composite laminates. The effect of fibre rotation on the measured shear properties, was for the first time experimentally quantified with the comparison between compression and tension tests of the ±45° laminate samples. Significant increase of shear strength and decrease of final failure strain was observed with the increase in strain rate from 5e-4 1/s to 1300 1/s. The nonlinear constitutive model was developed to simulate the large deformation process, in which the fibre orientation was updated as a function of the in-plane shear strain. The results of this investigation should motivate the updating of procedures for experimental characterization as well as analytical and numerical modelling of in-plane shear response of laminates.

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Section: Shear Response With Correction Of Fibre Rotation Effectmentioning

confidence: 96%

Effect of strain rate and fibre rotation on the in-plane shear response of ±45° laminates in tension and compression tests

Cui

Thomson

Pellegrino

et al. 2016

Composites Science and Technology

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show abstract

“…Furthermore, while some of these phenomena are associated with a decrease in modulus, such as plasticity and damage, a competing stiffening effect on the stress-strain curve is induced by others. In the case of loading in the x direction, the primary load carrying carbon fibres in the axial yarns exhibit stiffening due to their non-Hookean constitutive behaviour [26][27][28]. At the same time, minor undulations in axial bundles caused 255 by nesting effects of multiple braid plies diminish as the fibres align progressively with the load.…”

Section: Loading In the Axial (X) Directionmentioning

confidence: 99%

Damage and failure of triaxial braided composites under multi-axial stress states

Wehrkamp-Richter

Hinterhölzl

Pinho

2017

Composites Science and Technology

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Damage and failure of triaxial braided composites under multi-axial stress states was investigated. In order to introduce different multi-axial stress states in the material, uni-axial tensile tests were performed at different off-axis orientations. Three braid architectures, comprising braiding angles of 30 • , 45 • and 60 • were each loaded parallel to their axial, transverse and braid yarn direction. Digital image correlation measurement techniques were used to quantify the effects of the textile architecture and its heterogeneity on the strain field, to identify and locate constituent failure mechanisms and to investigate damage initiation and development. In order to identify the driving physical mechanisms behind the material non-linearity, the evolution of the damage variable and the accumulated inelastic strain was quantified using incremental loading/unloading experiments. A high-speed camera was employed in order to study the dynamic nature of catastrophic failure. The triaxial braids within this study exhibited severe non-linearities in the mechanical response before final failure as a result of extensive matrix cracking. While we found the underlying textile architecture to slightly reduce the elastic properties compared to equivalent tape laminates, it functions as a natural crack arresting grid. As a result of this mechanism, braids under certain load conditions were capable of withstanding a higher strain to failure, even if a large portion of the specimen surface was saturated with matrix cracks. The accompanying mechanical behaviour can be desirable in the design of crash absorbing or pseudo-ductile materials. An additional failure mode intrinsic to the textile architecture was encountered for loading in the heavily undulated braid yarn direction. Due to yarn straightening and out-of-plane movements, braided composites were found to fail as a result of large scale delaminations accompanied by progressive fibre bundle pull-out.

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“…The 1'-direction is aligned with the fiber direction of the nondeformed state. As shown in Mandel et al., 27 the deformation-induced rotation angle is given by the longitudinal shear strains ɛ'12 and ɛ'13 as and the orientation of the rotation axis is given by the vector The resulting rotation tensor R θ is …”

Section: Nonlinear Materials Modelmentioning

confidence: 98%

Influence of nonlinear material behavior on the effect of inter-fiber cracks in composite laminates

Taubert

Mandel

Hartmann

2017

Journal of Composite Materials

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This paper presents a numerical study evaluating the influence of nonlinear material behavior on the stiffness reduction due to inter-fiber cracks. It is shown that the relation between crack density and damage variables changes as the load level increases. A three-dimensional nonlinear material model is used in a representative volume element study to accurately calculate the local stress distribution around cracks. The studies show that as the load increases the stress recovers to the far-field level within a shorter distance, and consequently the plastic deformation causes a decrease in the crack-induced stiffness reduction. To provide damage variables for a coupled elastoplastic-damage material approach at the homogenized ply level, the results of a systematic representative volume element study are used for interpolation. For verification, the response curves of several laminates influenced by inter-fiber cracks are simulated and compared to experimental results. The presented procedure enables the constitutive laminate response under large deformations to be accurately predicted.

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Three-dimensional nonlinear constitutive model for composites

Cited by 18 publications

References 18 publications

Effect of strain rate and fibre rotation on the in-plane shear response of ±45° laminates in tension and compression tests

Effect of strain rate and fibre rotation on the in-plane shear response of ±45° laminates in tension and compression tests

Damage and failure of triaxial braided composites under multi-axial stress states

Influence of nonlinear material behavior on the effect of inter-fiber cracks in composite laminates

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