On the pop-in mode of fracture

Key, P. L.; Katz, Y.

doi:10.1007/bf00189940

Cited by 13 publications

(10 citation statements)

References 3 publications

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“…Key [18] found that the greatest value of GI occurs for an internal fiat elliptical crack propagating along its minor semi-axis b. This indicates that GI corresponding to Case 2 is energetically the most favourable growth mode of all the possible cracking possibilities.…”

Section: Internal Flat Elliptical Crackmentioning

confidence: 94%

“…For a 3-D flaw, 'global' energy release rates Gl may vary with possible virtual crack extensions (e.g. [18,19]). On the other hand, for a fiat crack with a curved front, 'local' stress intensity factors 1([ may vary along the crack front (e.g.…”

Section: Gl -Os Lxs-+o As'mentioning

confidence: 99%

“…The major weakness of this approach to the calculation of KI is the fact that an assumption of plane stress or plane strain near the crack front needs to be invoked to relate the pointwise energy release rate to the stress intensity factors [24]. Key [18] stated that these local values of GI have little physical significance. However, Li et al [25] considered pointwise values of the energy release rate along the crack front as a characterizing parameter of crack tip fields.…”

Section: Gl -Os Lxs-+o As'mentioning

confidence: 99%

“…Usually in tension testing, the critical energy release rate of a material is determined by specimens with a straight crack front along which all points are assumed to extend simultaneously and local energy release rates are approximately constant. Thus, it could be accepted that the critical energy release rate of the material is equal to the critical local energy release rate of the specimen as discussed in [ 18]. However, for a flat crack with a curved front, since a local energy release rate may be much higher than the maximum of all possible global energy release rates [18,22], local energy release rates may not be directly compared with the critical energy release rate of the material to predict crack extension from a general 3-D flaw.…”

Section: Gl -Os Lxs-+o As'mentioning

confidence: 99%

“…Key [18] provided the energy release rates due to the following three special virtual crack extensions.…”

Section: Internal Flat Elliptical Crackmentioning

confidence: 99%

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A 3-D approach to the calculation of the energy release rate in some fracture problems

Wang

Shrive

1994

Int J Fract

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A 3-D ellipsoidal flaw model is sufficiently versatile to cover a wide variety of flaw shapes: existing 2-D flaw models are special cases. The energy release rate from an eUipsoidal flaw in an infinite medium may be calculated by both a 'strain method' and a 'displacement method'. Solution techniques for both tension and compression are presented. The results calculated by both methods are in excellent agreement with available explicit results. The simpler and more efficient strain method is preferred in the calculation of the energy release rate for various flaws, except for line cracks and flat cracks subject to tensile stress normal to the crack plane. The 3-D formulation has considerable promise for providing understanding of the effects of various parameters on the energy release rate under triaxial stress states.

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Section: Internal Flat Elliptical Crackmentioning

confidence: 94%

Section: Gl -Os Lxs-+o As'mentioning

confidence: 99%

Section: Gl -Os Lxs-+o As'mentioning

confidence: 99%

Section: Gl -Os Lxs-+o As'mentioning

confidence: 99%

“…Key [18] provided the energy release rates due to the following three special virtual crack extensions.…”

Section: Internal Flat Elliptical Crackmentioning

confidence: 99%

See 3 more Smart Citations

A 3-D approach to the calculation of the energy release rate in some fracture problems

Wang

Shrive

1994

Int J Fract

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Impact strength of polymers: 1. The effect of thermal treatment and residual stress

Broutman

Krishnakumar

1976

Polymer Engineering & Sci

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The effect of thermal annealing and quenching on the notched Izod impact strength of several polymers has been studied. Primary emphasis was placed on polycarbonate, but ABS, PVC, polysulfone, and polymethylmethacrylate were also studied. It was determined that residual stresses created by thermal quenching from above the glass transition temperature can have a great effect on impact strength for the polycarbonate, PVC, and polysulfone polymers studied. In fact, it is shown that the thickness transition observed in impact strength for polycarbonates is governed by the residual stresses and not by thickness. In polycarbonates, quenched sheets up to 3/8 in. in thickness have shown impact strengths of 18 ft‐lb/in. whereas sheets 1/8 in. in thickness can be embrittled by annealing, showing an impact strength of 2 ft‐lb/in. However, it has been shown that this embrittlement results from the absence of residual stress. Residual stresses having maximum values up to 3000 psi (in Compression) have been determined at the polycarbonate sheet surface using birefringence measurement techniques. The existence of these compressive stresses is postulated to restrict the extent of craze growth at the notch tip, and the impact specimen can yield rather than fail in a brittle manner if the stress state is sufficient.

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Fractography of injection molded polycarbonate acrylonitrile‐butadiene‐styrene terpolymer blends

Lee

Hiltner

Baer

1992

Polymer Engineering & Sci

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Fractography has been used in the post-failure analysis of single edge notched specimens of injection molded blends of polycarbonate (PC) and acrylonitrilebutadiene-styrene terpolymer (ABS). The mode of ductile tensile fracture of single edge notched specimens depended on composition. Plane stress shear tearing was observed in the composition range PC/ABS 90, ' 10 to 70/30 by weight where PC was the continuous phase. Intermediate compositions, PC/ABS 60/40 to 40/60, had a co-continuous or almost co-continuous phase morphology; these blends fractured by mixed mode pop-in, where a tunneling center crack relieved the triaxiality and permitted plane stress shear lips to form near the edges. Hemngbone fracture, a plane strain mode characterized by discontinuous crack growth, was observed when Al3S was the continuous phase, PC/Al3S 30/70 to 10/90. An S-shaped relationship was observed between the ductile-to-brittle transition temperature and the composition. Addition of AI3S to PC increased ductility up to PC/AI3S 70/30 and 60/40, which were the most ductile compositions. Further addition of Al3S decreased the ductility, and the least ductile compositions were PC/AT3S 30/70 and 10/90.

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On the pop-in mode of fracture

Abstract: Expertmental observataons concerning the pop-m mode of fracture obtained during an investigation of the fracture toughness of glassy plastics are related. Comments on the mechanics of the pop-in mode are presented,

Cited by 13 publications

References 3 publications

A 3-D approach to the calculation of the energy release rate in some fracture problems

A 3-D approach to the calculation of the energy release rate in some fracture problems

Impact strength of polymers: 1. The effect of thermal treatment and residual stress

Fractography of injection molded polycarbonate acrylonitrile‐butadiene‐styrene terpolymer blends

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