Experimental characterisation of mixed mode traction–displacement relationships for a single carbon composite Z-pin

Yasaee, Mehdi; Lander, James K.; Allegri, Giuliano

doi:10.1016/j.compscitech.2014.02.001

Cited by 78 publications

(110 citation statements)

References 18 publications

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“…The consequence of these differences is important to understand when numerical or analytical models are developed to predict TTR composites with mode II delaminations. It is expected that the energy absorbed by pins loaded in pure mode II will be slightly lower than pins that experience some bending deformation before rupture [20], therefore using pure mode II energy absorption properties to model mode II fractures will produce conservative results.…”

Section: Discussionmentioning

confidence: 99%

“…al. [20] this results in a loading mode mixity, φ of 99%, regarded to be acceptable in the mode II regime. Six replicates of both the unpinned and pinned configurations with a width of 20mm, where machined from the same panel.…”

Section: Materials Manufacturing and Methodsmentioning

confidence: 99%

“…Resistance of pinned laminates to delamination has been shown to be different for a unidirectional (UD) relative to a non-UD stacking sequence [20]. Thereby the stacking sequence of the specimens for this investigation must be a non-UD type.…”

Section: Multiple Delamination Test Configurationmentioning

confidence: 99%

“…More often, for example when thick composites are subjected to impact loading, multiple delaminations are generated, which is the result of complex damage formation and interactions between matrix cracks, fibre failures and delaminations [24][25][26]. It has been shown that embedded Z-pins interact with the composite material on a structural level [20,27], in that the embedded length of the pins relative to the crack plane has a direct influence on their suppression of delamination propagation. For this reason, the reinforcement capability of a pin may be affected when more than one delamination is resisted.…”

Section: Introductionmentioning

confidence: 99%

“…For composites reinforced by Z-pins the majority characterisation work has been conducted on specimens containing a single embedded delamination using single pin tests [18][19][20] or simple fracture tests such as DCB, ENF, ELS, MMB tests [2,[21][22][23]. However, in practical engineering applications, composite structures seldom fail through a single delamination.…”

Section: Introductionmentioning

confidence: 99%

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Interaction of Z-pins with Multiple Mode II Delaminations in Composite Laminates

2016

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms AbstractThe application of Z-pinning is a subject of great interest in the field of through-thickness reinforcement (TTR) of composite laminates. To date, the majority of Z-pin characterisation work has been conducted on fracture coupons containing a single embedded delamination, which is often not representative of real failure of reinforced composite structures in service. In this investigation a test procedure to produce two independent Mode II delaminations was developed to analyse their interaction with a region of Z-pin reinforcement.Initially numerical models were used to optimise the chosen configuration. Experimental results show in detail the response of Z-pins to two independent delaminations. These results highlight the ability of the Z-pins to effectively arrest mode II delaminations at multiple levels through the sample thickness.Additionally they provide a much needed data set for validation and verification of Z-pin numerical modelling tools.

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Section: Discussionmentioning

confidence: 99%

Section: Materials Manufacturing and Methodsmentioning

confidence: 99%

Section: Multiple Delamination Test Configurationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Interaction of Z-pins with Multiple Mode II Delaminations in Composite Laminates

2016

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Capacities of Z‐pinning in improving the bending performance of composite T‐joints

Chen

et al. 2020

Polymer Composites

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The capacities of Z‐pinning in improving the bending performance of composite T‐joints were examined experimentally and numerically. It was found that Z‐pinning was not effective in enhancing the maximum bending load capacities of the T‐joints. Delamination at the interfaces of flange/filler, flange/flange, flange/skin, in the arc‐flange, as well as the fracture of the upper corner of the filler was observed. Among those failure patterns, the notorious delamination formed in the arc‐flange assumed the main responsibility of the disability of Z‐pinning in enhancing the maximum bending load capacity. Despite this, Z‐pinning was found to be highly effective in improving the residual plateau load‐carrying capacities of the T‐joints and the maximum bending displacement could also be dramatically increased, making the T‐joint maintain considerable bending load capacity under large deformation and preventing the T‐joint from catastrophe failure once the maximum bending load was attained.

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Delamination bridging response of Z‐pins under mixed mode loading: The influence of carbon and Kevlar Z‐pins

Gong,

Liao,

et al. 2024

Polymer Composites

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This paper presents the effect of varying the type of Z‐pin on the delamination bridging performance of unidirectional composite laminates. Carbon and Kevlar Z‐pins were inserted in thick composite laminates using the pre‐hole insertion Z‐pinning process and their bridging performance characterized across the different mode‐mixity range. The bridging response indicated that Kevlar Z‐pin experienced load reduction driven by interfacial friction (Stage III), which was absent in the Carbon Z‐pin. When Mode II dominated the bridging crack, Kevlar Z‐pin showed partial pullout and fiber shear cracking, while the Carbon Z‐pin exhibited clean transverse fracture. Although the bridging load obtained by the Carbon Z‐pin was twice that of Kevlar Z‐pin, the Kevlar Z‐pin provided a higher interlaminar fracture energy. The superior bridging performance of Kevlar Z‐pin is correlated with the enhanced ductility. Moreover, the resin‐rich area was involved in deformation and provided the extra axial load of Z‐pin.Highlights The comparison of mixed‐mode bridging mechanism between Kevlar Z‐pin and Carbon Z‐pin. Reveal the variation of multi‐directional load and energy consumption with mixed‐mode angle in thick laminates. Detailed scanning electron microscope observation to understand failure characteristics of ductile Z‐pin. Evidence that the extra axial load of Z‐pin provided by resin‐rich area.

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Experimental characterisation of mixed mode traction–displacement relationships for a single carbon composite Z-pin

Cited by 78 publications

References 18 publications

Interaction of Z-pins with Multiple Mode II Delaminations in Composite Laminates

Interaction of Z-pins with Multiple Mode II Delaminations in Composite Laminates

Capacities of Z‐pinning in improving the bending performance of composite T‐joints

Delamination bridging response of Z‐pins under mixed mode loading: The influence of carbon and Kevlar Z‐pins

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