Fiber fracture in the absence of bending during MMC processing

Koss, D. A.; Heaney, Donald F.; Gorey, N. M.; Hellmann, Jonathan

doi:10.1016/s0921-5093(96)10562-1

Cited by 4 publications

(10 citation statements)

References 12 publications

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“…In this case, we propose that fiber fracture may occur due to matrix flow along the fibers during the latter stages of hot pressing. The present article extends our earlier analysis [5] by addressing the conditions under which matrix flow within the die is expected to occur, and therefore under what conditions matrix flow-induced fiber fragmentation is expected, during hot pressing of a MMC in an open-ended channel die configuration. Our basis for assuming matrix flow is that hot-press consolidation of composites typically uses an open-ended die cavity, which is a procedure for processing convenience as well as for the necessity of gas evolution.…”

Section: Introductionmentioning

confidence: 63%

“…As is described in more detail elsewhere, [5] the physical basis for our analysis, as depicted in Figure 1, envisions matrix flow occurring in a plane-strain manner along the die cavity and, as a result, along the fibers. This situation may occur during the latter stages of hot pressing when the matrix is nearly fully dense and, as will be analyzed sub-sequently, when there is sufficient pressure to cause constrained matrix to flow along the die channel, despite friction between the die and workplace.…”

Section: Analysis: Extension-induced Fiber Fragmentationmentioning

confidence: 99%

“…Sapphire-reinforced metal matrix composites (MMCs) are especially susceptible to both types of fiber damage, [1][2][3][4][5] while SiC-reinforced MMCs are resistant to fiber strength degradation but can be susceptible to fiber fragmentation during processing. This problem can usually be traced to one or both of two processing-induced damage effects: fiber strength degradation and fiber fragmentation.…”

Section: Introductionmentioning

confidence: 99%

“…During hot pressing, it is well known that fibers may fragment as a result of fiber bending caused by the combination of the applied pressure and the presence of asperities, which result from powder particles, [7,8,11] monotape profiles, [7,8,10,11] or cross-weave wires in a foil/fiber/foil layup. [5,13] These observations suggest that fiber fragmentation can occur during composite processing even in the absence of bending. [7][8][9][10][11][12] Although fiber bending is usually observed when fiber fragmentation occurs, there have been observations of consolidation-induced fiber breakage in which the broken fibers appear straight with no indication of bending.…”

Section: Introductionmentioning

confidence: 99%

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Fiber fragmentation during processing of metallic matrix composites

Gorey

Koss

Hellmann

1998

Metall Mater Trans A

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Fiber fragmentation is a problem frequently encountered during the processing of metallic matrix composites. In this study, we examine the fragmentation of continuous fibers during a common composite consolidation process based on hot pressing in an open-ended channel die with fibers aligned parallel to the die walls. During the latter stages of consolidation, flow of the matrix along the die cavity may occur such that the resulting load transfer to the fibers can cause their fracture even in the absence of bending. This study analyzes the combination of conditions necessary for both matrix flow along the die cavity and the shear-lag loading of the fibers to a level that causes fragmentation. In order to validate the analysis, we model the fragmentation of fibers during elevated temperature hot pressing of Ni-base composites by the room-temperature consolidation of degraded sapphire fibers in a tin matrix. The observed fiber fragmentation behavior is in good agreement with theoretical predictions. The analysis also indicates that this mode of fiber fragmentation is confined either to low volume-fraction fiber composites or to the ends of panels of high volume-fraction fiber composites.

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Section: Introductionmentioning

confidence: 63%

Section: Analysis: Extension-induced Fiber Fragmentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fiber fragmentation during processing of metallic matrix composites

Gorey

Koss

Hellmann

1998

Metall Mater Trans A

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“…The posite manufacture by a variety of routes including foilimpact of sprayed droplets, typically with velocities of sevfiber-foil (FFF), powder cloth, matrix coated fiber (MCF), eral hundred meters per second, can cause severe thermal and thermal spraying. [3][4][5][6][7][8][9] shock and mechanical damage. [5] Fiber damage in subseLow pressure plasma spraying (LPPS) has been explored quent consolidation of monotapes, or foil/fiber preforms as an economic method of manufacturing continuous fiberobtained from other routes, has been studied extensively, reinforced metal matrix composites.…”

Section: Introductionmentioning

confidence: 99%

Strength degradation of SiC fiber during manufacture of titanium matrix composites by plasma spraying and hot pressing

Baik

Grant

2001

Metall Mater Trans A

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Titanium matrix composites (TMCs) reinforced with Sigma 1140ϩ SiC fiber have been manufactured by a combination of low pressure plasma spraying (LPPS spray/wind) and simultaneous fiber winding, followed by vacuum hot pressing (VHP). Fiber damage during TMC manufacture has been evaluated by measuring fiber tensile strength after fiber extraction from the TMCs at various processing stages, followed by fitting of these data to a Weibull distribution function. The LPPS spray/wind processing caused a decrease in mean fiber strength and Weibull modulus in comparison with as-received fibers. A number of fiber surface flaws, primarily in the outer C layer of the fiber, formed as a result of mechanical impact of poorly melted particles from the plasma spray. Coarse feedstock powders promoted an increase in the population of fiber surface flaws, leading to significant reduction in fiber strength. The VHP consolidation promoted further development of fiber surface flaws by fiber bending and stress localization because of nonuniform matrix shrinkage, resulting in further degradation in fiber strength. In the extreme case of fibers touching, the stress concentration on the fibers was sufficient to cause fiber cracking. Fractographic studies revealed that low strength fibers failed by surface flaw induced failure and contained a large fracture mirror zone. Compared with the more widely investigated foil-fiber-foil route to manufacture TMCs, LPPS/VHP resulted in less degradation in fiber strength for Sigma 1140ϩ fiber. Preliminary results for Textron SCS-6 fiber indicated a much greater tolerance to LPPS/VHP damage.

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Finite-element analysis of the hot-pressing consolidation of continuous Al₂O₃ fibers-reinforced NiAl composites

Chen

Gottstein

2005

International Journal of Materials Research

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The finite-element method was used to model the consolidation process of continuous Al2O3 fiber-reinforced NiAl composites. Actual creep behavior of NiAl was accounted for including the instantaneous strain and primary creep behavior. Primary creep played a very important role in the consolidation process at high temperatures and high pressures. Various processing parameters were investigated to evaluate the effects of temperature and hot-pressing stress on the consolidation behavior. It was found that the effect of pressure on consolidation was more significant at high temperatures due to its strong influence on the creep rate during power-law creep. The effects of fiber volume fraction and the arrangement of the matrix-coated fibers were also analysed. The simulations recommend an optimal fiber volume fraction in the range of 30 %–50 %. Fully dense composites were fabricated according to the predicted processing conditions, and good agreement between simulation and experiment was achieved.

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Fiber fracture in the absence of bending during MMC processing

Cited by 4 publications

References 12 publications

Fiber fragmentation during processing of metallic matrix composites

Fiber fragmentation during processing of metallic matrix composites

Strength degradation of SiC fiber during manufacture of titanium matrix composites by plasma spraying and hot pressing

Finite-element analysis of the hot-pressing consolidation of continuous Al₂O₃ fibers-reinforced NiAl composites

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Fiber fracture in the absence of bending during MMC processing

Cited by 4 publications

References 12 publications

Fiber fragmentation during processing of metallic matrix composites

Fiber fragmentation during processing of metallic matrix composites

Strength degradation of SiC fiber during manufacture of titanium matrix composites by plasma spraying and hot pressing

Finite-element analysis of the hot-pressing consolidation of continuous Al2O3 fibers-reinforced NiAl composites

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Product

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About

Finite-element analysis of the hot-pressing consolidation of continuous Al₂O₃ fibers-reinforced NiAl composites