Bending effect of through-thickness reinforcement rods on mode I delamination toughness of DCB specimen. I. Linearly elastic and rigid-perfectly plastic models

Tong, Liyong; Sun, Xiannian

doi:10.1016/j.ijsolstr.2004.06.010

Cited by 31 publications

(6 citation statements)

References 19 publications

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“…Further details on the test procedure can be found in Yasaee et al [14] and M'membe et al [10]. pins normally reported in the literature, the contribution of bending moments can be ignored because they are negated by the growth of cracks along the Z-pin longitudinal axis [5]. However, bending effects cannot be ignored for the metallic Z-pins and must be considered in the DCB analysis [5].…”

Section: Methodsmentioning

confidence: 99%

“…pins normally reported in the literature, the contribution of bending moments can be ignored because they are negated by the growth of cracks along the Z-pin longitudinal axis [5]. However, bending effects cannot be ignored for the metallic Z-pins and must be considered in the DCB analysis [5]. Experimental observations have shown that pull out typically occurs from one half of the specimen.…”

Section: Methodsmentioning

confidence: 99%

“…Schematic diagram of DCB specimens In pure Mode I tests such as those carried out for single pin specimens, Z-pins are loaded with a purely axial force. However, in DCB specimens, the Z-pins near the crack front have axial forces and bending moments exerted on them[5]. For carbon fibre Z-…”

mentioning

confidence: 99%

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Effective use of metallic Z-pins for composites' through-thickness reinforcement

M’membe

Yasaee

Hallett

et al. 2019

Composites Science and Technology

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Z-pins offer effective through-thickness reinforcement for laminated composites. Various studies have however shown that metal Z-pins are less effective at bridging Mode I delaminations than carbon-fibre composite Z-pins, due to poor interfacial bonding with the laminate. This is exacerbated by high thermal mismatch between the metallic Z-pins and the laminate. This study investigates inserting metallic Z-pins at angles offset from the laminate normal, to improve the Mode I bridging in composites. The effects on the apparent fracture toughness under pure and mixed Mode I/II loads using single pin specimens is investigated. Results show that, unlike orthogonally inserted metal Z-pins, inclined Z-pins exhibit high energy absorption throughout the mixed mode range. Double Cantilever Beam (DCB) tests show that the inclined metal Z-pins increase the Mode I apparent fracture toughness by a factor of 2 compared to traditional carbon fibre Z-pins. In End Loaded Split (ELS) tests, the Mode II apparent fracture toughness of inclined stainless steel Z-pins, although less than their uninclined

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Effective use of metallic Z-pins for composites' through-thickness reinforcement

M’membe

Yasaee

Hallett

et al. 2019

Composites Science and Technology

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“…Some researchers consider the bridging effect provided by the through-thickness reinforcements to have a constant bridging length and therefore, total C G can be calculated by averaging the energy dissipation rates over the reinforced area [10,17]. However, this assumption seems more appropriate for SSB than LSB; in the latter case the pin bridging force varies during the fracture process and thus, (2) each pin traction is treated as a concentrated force acting at the pin location and governed by a non-linear force-displacement relation [7,11,17,26]. When the first approach is employed, the bridging relation is defined as either a stressdisplacement relation [9,10] or the stiffness of an elastic foundation [12].…”

Section: Energy Balance During Crack Bridgingmentioning

confidence: 99%

“…A number of models have been developed for predicting delamination suppression in zpinned laminates. These models are either analytical [9][10][11][12][13] or numerical using the finite element method [7,[14][15][16]. Z-pin bridging effect is modelled by averaging the bridging forces over the entire reinforced area [9][10][11][12][14][15][16], or by the classic beam theory [11][12][13], or nonlinear springs exerting concentrated traction force at the pin location [7,[13][14]17].…”

Section: Introductionmentioning

confidence: 99%

A cohesive zone model for predicting delamination suppression in z-pinned laminates

Bianchi

Zhang

2011

Composites Science and Technology

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This paper presents a cohesive zone model based finite element analysis of delamination resistance of z-pin reinforced double cantilever beam (DCB). The main difference between this and existing cohesive zone models is that each z-pin bridging force is governed by a traction-separation law derived from a meso-mechanical model of the pin pullout process, which is independent of the fracture toughness of unreinforced laminate. Therefore, two different traction-separation laws are used: one representing the toughness of unreinforced laminate and the other the enhanced delamination toughness owing to the pin bridging action. This approach can account for the large scale bridging effect and avoid using concentrated pin forces, thus removing the mesh dependency and permitting more accurate analysis solution. Computations were performed using a simplified unit strip model. Predicted delamination growth and load vs. displacement relation are in excellent agreement with the prediction by a complete model, and both models are in good agreement with test measured load vs. displacement relation. For a pinned DCB specimen, the unit strip model can reduce the computing time by 85%.

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Mode I and Mode II delamination resistance and mechanical properties of woven glass/epoxy–PU IPN composites

et al. 2008

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The effect of polyurethane on the mechanical properties and Mode I and Mode II interlaminar fracture toughness of glass/epoxy composites were studied. Polyurethanes (PU) synthesized using polyols and toluene diisocyanate were employed as modifier for epoxy resin by forming interpenetrating polymer network. The PU/Epoxy IPN was used as matrix material for GFRP. PU modified epoxy composite laminates having varying PU contents were prepared. The effect of PU content on the mechanical properties like interlaminar fracture toughness (Mode I, G 1c and Mode II, G IIc ), tensile strength, flexural strength, and Izod impact strength were studied. The morphological studies were conducted on the fractured surface of the composite specimen by scanning electron microscopy (SEM). Tensile strength, flexural strength, and impact strength of PU-modified epoxy composite laminates were found to increase inline with interlaminar fracture toughness (G 1c and G IIc ) with increasing PU content to a certain limit and then it was found to decrease with increase in PU content. It was observed that toughening of epoxy with PU increases the Mode I and Mode II delamination toughness up to 17 and 120% higher than that of untoughened composite specimen, respectively. POLYM. COMPOS.

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Bending effect of through-thickness reinforcement rods on mode I delamination toughness of DCB specimen. I. Linearly elastic and rigid-perfectly plastic models

Cited by 31 publications

References 19 publications

Effective use of metallic Z-pins for composites' through-thickness reinforcement

Effective use of metallic Z-pins for composites' through-thickness reinforcement

A cohesive zone model for predicting delamination suppression in z-pinned laminates

Mode I and Mode II delamination resistance and mechanical properties of woven glass/epoxy–PU IPN composites

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