Viscoelastically Prestressed Polymeric Matrix Composites

Fancey, Kevin S.

doi:10.1002/9783527645213.ch22

Cited by 3 publications

(8 citation statements)

References 47 publications

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“…Subsequently, however, design and construction of improved equipment enabled the fibre stretching capacity to be increased by an order of magnitude. 32 To study flexural stiffness, 33 samples were produced using the open casting method outlined earlier. In this case, however, an epoxy resin matrix and higher V f values (8-16%) were utilised.…”

Section: Other Mechanical Testsmentioning

confidence: 99%

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Viscoelastically prestressed polymeric matrix composites: An overview

Fancey

2016

Journal of Reinforced Plastics and Composites

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Elastically prestressed polymeric matrix composites exploit the principles of prestressed concrete, i.e. fibres are stretched elastically during matrix curing. On matrix solidification, compressive stresses are created within the matrix, counterbalanced by residual fibre tension. Unidirectional glass fibre elastically prestressed polymeric matrix composites have demonstrated 25–50% improvements in impact toughness, strength and stiffness compared with control (unstressed) counterparts. Although these benefits require no increase in section dimensions or weight, the need to apply fibre tension during curing can impose restrictions on processing and product geometry. Also, fibre–matrix interfacial creep may eventually cause the prestress to deteriorate. This paper gives an overview of an alternative approach: viscoelastically prestressed polymeric matrix composites. Here, polymeric fibres are subjected to tensile creep, the applied load being removed before the fibres are moulded into the matrix. Following matrix curing, viscoelastic recovery mechanisms cause the previously strained fibres to impart compressive stresses to the matrix. Since fibre stretching and moulding operations are decoupled, viscoelastically prestressed polymeric matrix composite production offers considerable flexibility. Also, the potential for deterioration through fibre–matrix creep is offset by longer term viscoelastic recovery mechanisms. To date, viscoelastically prestressed viscoelastically prestressed polymeric matrix composites have been produced from fibre reinforcements such as nylon 6,6, ultra-high molecular weight polyethylene and bamboo. Compared with control counterparts, mechanical property improvements are similar to those of elastically prestressed polymeric matrix composites. Of major importance, however, is longevity: through accelerated ageing, nylon fibre-based viscoelastically prestressed viscoelastically prestressed polymeric matrix composites show no deterioration in mechanical performance over a duration equivalent to ∼25 years at 50℃ ambient. Potential applications include crashworthy and impact-absorbing structures, dental materials, prestressed precast concrete and shape-changing (morphing) structures.

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Section: Other Mechanical Testsmentioning

confidence: 99%

“…Subsequently, however, design and construction of improved equipment enabled the fibre stretching capacity to be increased by an order of magnitude. 32…”

Section: Prestress Based On Viscoelasticitymentioning

confidence: 99%

Viscoelastically prestressed polymeric matrix composites: An overview

Fancey

2016

Journal of Reinforced Plastics and Composites

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“…As an alternative approach to the EPPMC route, the mechanical properties of a PMC can be improved by exploiting the viscoelastic characteristics of certain fibre reinforcements. Viscoelastically prestressed polymeric matrix composites (VPPMCs) have demonstrated such improvements, in comparison with their unstressed counterparts, without the need to increase section size or weight [18]. Published results have shown 20-50% increases in Charpy impact strength and flexural stiffness [19][20][21][22][23][24] and up to 15% improvement in tensile strength [25] for nylon 6,6 fibre-based VPPMCs.…”

Section: Introductionmentioning

confidence: 99%

“…To produce a VPPMC, the fibre reinforcement is first subjected to a tensile creep load for a designated time period; after removing the load, the loose fibres are moulded into a resin matrix. Following resin solidification, the viscoelastically recovering fibres generate compressive stresses within the matrix, which are counterbalanced by residual tension within the fibres [18].…”

Section: Introductionmentioning

confidence: 99%

“…Thus a longevity study using accelerated ageing has shown no degradation in Charpy impact performance over a period equivalent to 25 years at a constant 50 °C with nylon 6,6 fibre-based VPPMCs [22]. Moreover, in contrast with EPPMC production, the fibre stretching and moulding processes are decoupled in VPPMC manufacturing, offering potentially significant benefits: (i) after releasing the stretching load, the fibre reinforcement can be chopped to any length and moulded into the resin matrix in any orientation; (ii) VPPMC production has no geometrical limitations; (iii) the stretching equipment can be relatively simple [18].…”

Section: Introductionmentioning

confidence: 99%

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Viscoelastically prestressed polymeric matrix composites – Effects of delayed moulding on Charpy impact properties

Qin

Fancey

2019

Composites Part A: Applied Science and Manufacturing

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Viscoelastically prestressed polymeric matrix composites (VPPMCs) are produced by subjecting fibres to creep, then releasing the creep load before moulding. Previous work has demonstrated mechanical property improvements up to ~50% from nylon 6,6 fibre-polyester resin VPPMCs, compared with control (unstressed) counterparts. Since fibre stretching and moulding processes are decoupled, the time interval between releasing the fibre stretching load and moulding (delayed moulding) offers considerable production flexibility. This paper investigates delayed moulding over 0-1272 h, using fibres stored at 20 °C and -25.4 °C. Charpy impact tests demonstrated increased energy absorption from all VPPMC samples compared with control counterparts, this increase reducing with delayed moulding time. A 1272 h delay gave an increase of ~23% for fibre storage at 20 °C, and ~40% at -25.4 °C, the latter demonstrating "decelerated" ageing. For all samples, the magnitude of fibre-matrix debonding (the principal energy absorption mechanism) increased linearly with impact energy data.

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Viscoelastically active sutures – A stitch in time?

Fancey

2021

Materials Science and Engineering: C

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Viscoelastically Prestressed Polymeric Matrix Composites

Cited by 3 publications

References 47 publications

Viscoelastically prestressed polymeric matrix composites: An overview

Viscoelastically prestressed polymeric matrix composites: An overview

Viscoelastically prestressed polymeric matrix composites – Effects of delayed moulding on Charpy impact properties

Viscoelastically active sutures – A stitch in time?

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