Failure Mechanisms in Fibre Reinforced Rigid Polyurethane Foam

Cotgreave, T.; Shortall, J. B.

doi:10.1177/0021955x7701300401

Cited by 15 publications

(6 citation statements)

References 4 publications

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“…The reinforcing effect will obviously not be improved even if the fiber length surpasses the optimal value. The critical fiber length value can be expressed as 17 :…”

Section: Effect Of Fiber Length On the Tensile Strength Of The Pu Commentioning

confidence: 99%

Study on the mechanical properties of hybrid reinforced rigid polyurethane composite foam

Yang

Zhao

Qin

et al. 2004

J of Applied Polymer Sci

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ABSTRACT:The mechanical properties of hybrid reinforced rigid polyurethane (PU) foams were investigated with the reinforcing agent SiO 2 and fibers. The effect of content of SiO 2 and fibers and the effect of length of fibers on the properties of the PU composite foam were emphatically analyzed. The experiment results show that the tensile strength of the PU composite foam is optimal when the content of SiO 2 and glass fiber is 20 and 7.8%, respectively. Furthermore, the reinforcing effect of glass fiber, Nylon-66 fiber, and PAN-matrix carbon fiber were compared and the results show that the tensile strength of the PU composite foam reinforced with 3-5% carbon fiber is optimal.

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“…The reinforcing effect will obviously not be improved even if the fiber length surpasses the optimal value. The critical fiber length value can be expressed as 17 :…”

Section: Effect Of Fiber Length On the Tensile Strength Of The Pu Commentioning

confidence: 99%

Study on the mechanical properties of hybrid reinforced rigid polyurethane composite foam

Yang

Zhao

Qin

et al. 2004

J of Applied Polymer Sci

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“…The most accepted mechanism for fatigue crack growth in cellular solids is the failure of a cell wall ahead of the crack tip after repeated flexure, causing a step‐wise crack growth, one cell at a time 9 . Empirical observations of crack propagation through cell walls and the adjacent struts confirm this 10,11 . Huang and Lin 12 have proposed a model for fatigue crack growth rate consistent with this mechanism.…”

Section: Fatigue and Fracture Of Pu Foam—state Of The Artmentioning

confidence: 91%

“…9 Empirical observations of crack propagation through cell walls and the adjacent struts confirm this. 10,11 Huang and Lin 12 have proposed a model for fatigue crack growth rate consistent with this mechanism. They conclude that fatigue of cellular materials depends on cyclic stress intensity range, cell size, relative density and the fatigue parameters of the solid from which they are made.…”

Section: Fatigue and Fracture Of Pu Foam-state Of The Artmentioning

confidence: 95%

“…Their model relates crack propagation rate behaviour with their un-notched fatigue life. However, it is reported that crack propagation in foams is interrupted by crack bridging by cell edges, 10,14 which differentiates crack propagation in foams from that in solids. In this regard, Olurin 15 suggests that the fatigue crack growth rate in an aluminium alloy foam is controlled by the progressive degradation of crack bridging by fatigue failure of the cell edges behind the crack tip.…”

Section: Fatigue and Fracture Of Pu Foam-state Of The Artmentioning

confidence: 99%

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Effects of thermal and mechanical cyclic loads on polyurethane pre‐insulated pipes

Doyle

Weidlich

2020

Fatigue Fract Eng Mat Struct

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District heating (DH) pre-insulated pipes are a sandwich assembly composed by a steel heat service pipe, polyurethane (PU) foam and polyethylene casing. The foam acts as bond between the steel pipe and casing. The application has high constraints for the foam, as it is subjected to cyclic multiaxial stresses, high cyclic temperatures and long expected service life. In this study, we evaluate if and how cyclic loads affect the shear strength, shear modulus, toughness and failure behaviour of the PU foam in DH pipes sandwich assembly compared with unaged reference samples. We have found that the simultaneous application of mechanical and thermal loads weakens the strength and increases the stiffness of the foam and that this change is not caused by degradation of the molecular structure. Crack initiation and propagation along the pipe samples follow a very consistent pattern between samples, with cracks initiating in Mode II and propagating in Mode I. The consistent axial displacement of approximately 2 cm from each other suggests the formation of strain localizations.

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“…Liang et al showed that coupling agents play a critical role on enhancement of wood polystyrene composites [11]. Cotgreave and Shortall [1] studied the reinforcement of low-density polyurethane foam by chopped glass fibers and investigated the failure mechanism of the resulting products. When fibers were added into foam, the regular cellular structure was dramatically changed and composite struts formed.…”

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confidence: 99%

Expanded Wood Fiber Polystyrene Composites: Processing–Structure–Mechanical Properties Relationships

Doroudiani¹,

Kortschot

2004

Journal of Thermoplastic Composite Materials

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In this study, processing-structure-mechanical properties relationships in expanded wood fiber polystyrene composites (EPSC) made with a physical blowing agent were investigated. A systematic investigation was performed based on a statistical experimental design. The samples were saturated with carbon dioxide at high pressure and ambient temperature and the saturated specimens were expanded at elevated temperatures. The relations between impact and tensile properties of EPSC and foaming process and structure were studied. Fiber content was found to be the most important parameter controlling impact strength and tensile modulus. The impact strength of EPSC was increased about three times when the fiber content increased to 20%. Using the Halpin-Tsai equation, a model was developed to relate tensile modulus to the density of EPSC.

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Failure Mechanisms in Fibre Reinforced Rigid Polyurethane Foam

Cited by 15 publications

References 4 publications

Study on the mechanical properties of hybrid reinforced rigid polyurethane composite foam

Study on the mechanical properties of hybrid reinforced rigid polyurethane composite foam

Effects of thermal and mechanical cyclic loads on polyurethane pre‐insulated pipes

Expanded Wood Fiber Polystyrene Composites: Processing–Structure–Mechanical Properties Relationships

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