A bistable morphing composite using viscoelastically generated prestress

Wang, Bing; Fancey, Kevin S.

doi:10.1016/j.matlet.2015.05.129

Cited by 39 publications

(35 citation statements)

References 9 publications

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“…The first VPPMCs to be successfully demonstrated utilized polyamide 6,6 fiber and their development has progressed, leading to, for example, commingled polyamide 6,6‐aramid fiber VPPMCs for enhanced mechanical performance . Most recently, polyamide 6,6 fiber has been used to produce the first bistable morphing structure based on VPPMC principles, and this may provide opportunities to develop morphing aerofoils for aerospace and other applications . Thus it is the fiber material under investigation in this article.…”

Section: Introductionmentioning

confidence: 99%

Application of time–stress superposition to viscoelastic behavior of polyamide 6,6 fiber and its “true” elastic modulus

Wang

Fancey

2017

J of Applied Polymer Sci

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The viscoelastic behavior of semi-crystalline polyamide 6,6 fiber is exploited in viscoelastically prestressed polymeric matrix composites. To understand better the underlying prestress mechanisms, strain-time performance of the fiber material is investigated in this work, under high creep stress values (330-665 MPa). A latch-based Weibull model enables prediction of the "true" elastic modulus through instantaneous deformation from the creep-recovery data, giving 4.6 6 0.4 GPa. The fiber shows approximate linear viscoelastic characteristics, so that the time-stress superposition principle (TSSP) can be implemented, with a linear relationship between the stress shift factor and applied stress. The resulting master creep curve enables creep behavior at 330 MPa to be predicted over a large timescale, thus creep at 590 MPa for 24 h would be equivalent to a 330 MPa creep stress for 5200 years. Similarly, the TSSP is applied to the resulting recovery data, to obtain a master recovery curve. This is equivalent to load removal in the master creep curve, in which the yarns would have been subjected to 330 MPa creep stress for 4.56 3 10 7 h. Since our work involves high stress values, the findings may be of interest to those involved with long-term load-bearing applications using polyamide materials.

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Section: Introductionmentioning

confidence: 99%

Application of time–stress superposition to viscoelastic behavior of polyamide 6,6 fiber and its “true” elastic modulus

Wang

Fancey

2017

J of Applied Polymer Sci

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“…Subject to avoiding fibre damage, however, it may be possible to reduce this creep time further, possibly down to several minutes. From the three creep settings investigated, elapsed recovery strain values were similar; moreover, Charpy impact test data from corresponding VPPMC samples showed no significant 56,57 differences in impact energy absorption, these being $56% greater than their control counterparts. 44 As outlined earlier, the decoupling of fibre stretching and moulding operations in VPPMC production facilitates the manufacture of complex composite structures.…”

Section: Prestress: Towards Process Optimisation and Production Flexibilitymentioning

confidence: 86%

“…This consists of VPPMC strips bonded to the sides of a thin, flexible resin-impregnated fibre-glass sheet. 56,57 Each strip has an inherent deflection from bending forces caused by non-uniform fibre spatial distributions. This enables pairs of strips to be orientated to give opposing cylindrical configurations within the sheet, thereby enabling the sheet to snapthrough between two states.…”

Section: Shape-changing (Morphing) Structures Based On Vppmc Technologymentioning

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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“…Carbon fiber/epoxy bistable composite shells have potential applications in aeronautical and mechanical engineering due to their multifunctional advantages and superior mechanical properties [1]. Several studies have been done on bistable behaviour of laminated cylindrical shells in recent years [2][3][4][5][6][7][8][9][10]. The bistable characteristics in high-temperature environment depends largely on the mechanical properties of fiber reinforced polymer composites around or above the glass transition temperature (T g ) of the resin matrix [11][12].…”

Section: Introductionmentioning

confidence: 99%

Bistable behaviour and microstructure characterization of carbon fiber/epoxy resin anti-symmetric laminated cylindrical shell after thermal exposure

Zhang

et al. 2017

Composites Science and Technology

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A bistable morphing composite using viscoelastically generated prestress

Cited by 39 publications

References 9 publications

Application of time–stress superposition to viscoelastic behavior of polyamide 6,6 fiber and its “true” elastic modulus

Application of time–stress superposition to viscoelastic behavior of polyamide 6,6 fiber and its “true” elastic modulus

Viscoelastically prestressed polymeric matrix composites: An overview

Bistable behaviour and microstructure characterization of carbon fiber/epoxy resin anti-symmetric laminated cylindrical shell after thermal exposure

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