A photoelastic study of the shear stresses associated with the transfer of stress during fibre reinforcement

Tyson, W. R.; Davies, G J

doi:10.1088/0508-3443/16/2/313

Cited by 154 publications

(36 citation statements)

References 2 publications

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“…[3][4][5][6] Tyson and Davies found by photoelastic experiments that interfacial shear stresses were higher than theories predict, most notably at the fiber ends.…”

Section: Volume Fraction and Fiber End Effectsmentioning

confidence: 99%

“…Tyson and Davies found interfacial shear stresses have been exceptionally high at fiber ends, 3) while in injection molded short 6.4 mm, 20 and 30 mass% Eglass fiber reinforced polyvinyl chloride (PVC), cracks have been found to initiate at fiber ends. [4][5][6] By shortening the fiber to sub-millimeter length, the resulting higher fiber end density may act to increase relaxation sites impeding crack growth above the critical length, 2a c .…”

Section: Introductionmentioning

confidence: 99%

“…11,12) To conform with these findings, that it is possible to increase fracture strain and tensile strength by shortening fibers in the BMC-GFRP the effects of sub-millimeter fibers on fracture strain and tensile strength have been investigated. 3.00 mass% aluminum silicate, and 0.10 mass% magnesium oxide. 13) A matrix composite without glass fibers was made for comparison and had an identical composition as the fiber-containing samples omitting the fibers.…”

Section: Introductionmentioning

confidence: 99%

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Tensile Strength Enhancement by Shortening Glass Fibers with Sub-Millimeter Length in Bulk Molding Polymer Compound

Faudree

Nishi

2010

Mater. Trans.

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Effects of short fiber with sub-millimeter length on tensile strain, " f and tensile strength, f were investigated for a bulk molding compound (BMC) glass fiber reinforced polymer (GFRP) composite with 20 mass% E-short glass fibers. The " f and f values of BMC-GFRP samples with 0.44 mm short fibers were almost 40 and 60% higher than that of BMC-GFRP samples with long fibers (3.2 and 6.4 mm in length), as well as more than 65 and 110% higher than that of the filled fiber free resin, respectively. The reduced fracture strain (" f =" f,6.4 ) and reduced tensile strength ( f = f,6.4 ) as a function of the fiber end density, E (cm À3 ) were expressed by the following equations with linear regression as (" f =" f,6.4 ¼ 1:21 Â 10 À7 E þ 0:965) and ( f = f,6.4 ¼ 1:51 Â 10 À7 E þ 0:998). Acoustic emission (AE) analysis detected microcracking was increased threefold by shortening the mean fiber length from 6.4 to 0.44 mm. Scanning electron microscopy (SEM) results showed increased fiber/matrix debonding at fiber ends and along fiber lengths in the 0.44 mm samples compared with that reported for 6.4 mm samples. The fiber debonding is thought to impart an internal strain field in the matrix surrounding each fiber resulting in volume expansion sites, hence compressive stress sites which absorb energy from an approaching crack tip front in the nearby vicinity halting the crack's advance. Therefore, more microcracks can be tolerated increasing fracture strain. Moreover, the critical crack length range for thermoset polymers was calculated to be approximately 0:50 < 2a c < 5:0 mm from reported K IC results in the literature, and is greater than the 0.44 mm mean fiber length. The probability of a microcrack propagating above 0.44 mm before it encounters a matrix compressive site, therefore is reduced. Furthermore, increased microcracking in the vicinity of the main crack tip acts to reduce the main crack tip stress concentration. All of these serve to prevent crack propagation resulting in enhancement of fracture strain in the

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“…[3][4][5][6] Tyson and Davies found by photoelastic experiments that interfacial shear stresses were higher than theories predict, most notably at the fiber ends.…”

Section: Volume Fraction and Fiber End Effectsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Tensile Strength Enhancement by Shortening Glass Fibers with Sub-Millimeter Length in Bulk Molding Polymer Compound

Faudree

Nishi

2010

Mater. Trans.

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“…The out-of-plane stress components due to actuation of the SMA wire are negligible compared to the axial direction. Several previous photoelastic studies of single-fiber composites have also assumed 22 25 22 a two-dimensional stress state. -Tyson and Davies and MacLaughlin z3 used a two-dimensional planar model to approximate the shear stresses at the edge of an embedded fiber.…”

Section: Nf~mentioning

confidence: 99%

Local displacements and load transfer in shape memory alloy composites

Jonnalagadda

Kline

Sottos

1997

Experimental Mechanics

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ABSTRACT--Although there has been a significant amount of research dedicated to characterizing and modeling the response of shape memory alloys (SMAs) alone, little experimental work has been done to understand the behavior of SMAs embedded in a host material. The interaction between SMA wires and a host polymer matrix was investigated by correlating local displacements and stress fields induced by the embedded wires with SMA/poiymer adhesion. Most $MA composite applications require transfer of strain from the wire to the matrix, in these applications, maximum interfacial adhesion between the SMA wire and the polymer matrix is most desirable. The adhesion was varied by considering four different surface treatments: untreated, acid etched, hand sanded and sandblasted. The average interfacial bond strength of the SMA wires embedded in an epoxy matrix was measured by standard pull out tests. Sandblasting significantly increased the bond strength, whereas hand sanding and acid cleaning actually reduced interface strength. In situ displacements of embedded, surface-treated SMA wires were measured using heterodyne interferometry, whereas the resulting stresses induced in the polymer matrix were investigated using photoelasticity. Increased wire adhesion resulted in lower axial wire displacement and higher interfacial stresses due to the restraining effect of the matrix on the actuated wire. A simplified theoretical analysis was carried out to estimate the shear stress induced in the matrix due to wire actuation. The maximum shear stress predicted for the case of a perfect interracial bond was about 7 percent larger than the value measured experimentally for the sandblasted wire.

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“…Photoelasticity is a well-known technique that has been successfully used to experimentally measure the stress fields and the debonding process at a fiber-matrix interface [12,13]. The photoelastic technique allows the observation of the stress distribution and the identification of micromechanical events [14].…”

Section: Introductionmentioning

confidence: 99%

Photoelastic evaluation of fiber surface-treatments on the interfacial performance of a polyester fiber/epoxy model composite

Flores‐Johnson¹,

Vázquez‐Rodríguez²,

Herrera‐Franco³

et al. 2011

Composites Part A: Applied Science and Manufacturing

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Abstract:The interfacial adhesion between a polyester fiber and an epoxy matrix was improved by chemical and topological modifications of the fiber surface. The maximum interfacial shear strength was measured using photoelasticity to assess the interfacial performance in pull-out single-fiber composite specimens. An increase of the interfacial shear strength was observed when plasma-treated or surface-modified fibers were used; also, as the applied load to the free fiber was increased, the fiber treatment caused a reduction of the debonded area at the fiber-matrix interface.

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A photoelastic study of the shear stresses associated with the transfer of stress during fibre reinforcement

Cited by 154 publications

References 2 publications

Tensile Strength Enhancement by Shortening Glass Fibers with Sub-Millimeter Length in Bulk Molding Polymer Compound

Tensile Strength Enhancement by Shortening Glass Fibers with Sub-Millimeter Length in Bulk Molding Polymer Compound

Local displacements and load transfer in shape memory alloy composites

Photoelastic evaluation of fiber surface-treatments on the interfacial performance of a polyester fiber/epoxy model composite

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