Stability of cracking

Gurney, C.; Mai, Yiu‐Wing

doi:10.1016/0013-7944(72)90020-3

Cited by 72 publications

(39 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The critical value of r above which the hypothesis of independence of R and Gic could be rejected was 0.514 at the 95% level of confidence. The correlation between the experimental technique for the measurement of R developed by Gumey and Mai [3] and the theoretical technique for the calculation of Gic from linear elastic fracture mechanics [1 ] was confirmed even though amalgam has been found to exhibit viscoelastic behaviour [10].…”

Section: Figurementioning

confidence: 98%

“…Irwin [1 ] derived the mathematical formulations of the critical stress intensity factor and the critical strain energy release rate from the experimental work of Griffith [2]. Gurney and Mai [3] developed an experimental technique for measurement of the energy necessary for crack propagation or fracture toughness. The work of Roberts et al [4] showed a correlation between fracture toughness and single-pass wear data of commercial and experimental dental restorative resins and composites.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fracture toughness and critical strain energy release rate of dental amalgam

1978

View full text Add to dashboard Cite

Fracture toughness, critical strain energy release rate and critical stress intensity factor were determined for lathe-cut, spherical, admixed, and two atomized high-copper dental amalgams. At a loading rate of 0.005cm min -1 for 24-hour samples, the spherical amalgam had the highest resistance to unstable crack propagation. At a loading rate of 0.05 cm min -1 for both 24-hour and one-month samples, the lathe-cut amalgam had the highest resistance to unstable crack propagation. One of the atomized high copper amalgams showed the lowest resistance to crack propagation. The values were consistent with data obtained in single-pass wear studies.

show abstract

Section: Figurementioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Fracture toughness and critical strain energy release rate of dental amalgam

1978

View full text Add to dashboard Cite

show abstract

“…The third factor which may control the fracture is the stabiity of cracking. Gurney and Mai [28] have derived the conditions for stable crack propagation starting from the basic equation of energy balance for the creation of two surfaces. The difference in work done on the system by external forces, dW, and the increase in the stored elastic energy, dU, is equal to the energy available for the formation of crack surfaces, i.e.…”

Section: Detailed Consideration Of Factors Influencing Stability Of Cmentioning

confidence: 99%

A double-torsion study of the fracture of polyethersulphone

1984

View full text Add to dashboard Cite

Fracture studies of polyethersulphone have been undertaken using the double torsion geometry, in particular to establish the effects of ageing and crack speed on fracture toughness. The stability of crack growth was found in all cases to be very dependent on initial notching. If by suitable techniques, e.g. fatigue, a craze was formed at the notch root the subsequent crack growth was found to be stable, with a craze ahead of the growing crack. Under these conditions only a slight dependence of fracture toughness on crack speed was observed, with no significant differences between material aged for 5 years at room temperature and freshly moulded samples. The dimensions of the observed craze were found to be very similar to those of crazes observed in a parallel study using compact tension geometry and lead to comparable values for craze stress and crack opening displacement. In many instances unstable crack growth was observed, often described as "stick-slip". This was often associated with the absence of a craze at the crack tip, perhaps due to a damage zone created during razor notching. The initiation load and load for crack arrest were determined and used to calculate initiation and arrest values for the fracture toughness as a function of the applied deformation rate. It was found that these values converged at high crosshead speeds to a value independent of ageing, although for the freshly moulded material the initiation values were significantly higher, and the arrest values lower. Electrically conducting grids were used to establish that crack speeds up to 400 m sec -1 occur during stick-slip crack growth. A detailed discussion is presented of conditions required for stable and unstable crack growth in polyethersu Iphone.

show abstract

“…3; full details are given in [8]. While there is no simple algebraic relation for (X,u,R,A) for this geometry, it is possible to measure U from the experimental results for a cracked glass ring given in Fig.…”

Section: Jr = 2ua~jbbo =R +R(aa/bo)mentioning

confidence: 99%

“…While there is no simple algebraic relation for (X,u,R,A) for this geometry, it is possible to measure U from the experimental results for a cracked glass ring given in Fig. 5 of [8]. Note that for crack growth at short crack lengths, U.= decreases.…”

Section: Jr = 2ua~jbbo =R +R(aa/bo)mentioning

confidence: 99%

Linear elastic JR Curves?The fallacy of increased resistance to fracture

Atkins

1991

Int J Fract

View full text Add to dashboard Cite

JR curves in elastoplastic fracture are customarily obtained by measuring the accumulated work U= under load up to various propagated crack lengths a, and plotting (in the case of notched 3-point bend bars, for example) flU ffBbo versus Aa or versus Aafoo where 11 is Turner's factor (=2 for deeply notched bend bars), B is beam thickness, bo is the starting ligament length and Aa =(a-ao) where ao is the starting crack length; for a beam of depth w, bo = w -ao. U= comprises two parts: U~, up to the initiation of cracking and U . Sometimes the elastic energy under load A is removed from U= and ri(U -A)I~o is used for the ordinate which may then be called JR~,' see Fig. 1.In a research note on the scaling of JR curves [1] it was shown that a simple algebraic model for notched bending gave JR = 2Ua~JBbo =R +R(Aa/bo)where R is the fracture toughness (equivalent to Jo or Ji) which suggested how JR curves from specimens with different bo could be scaled. At the time it was thought that the model represented a rigid-plastic solution; subsequently, it was realised that the model conforms instead to non-linear elasticity [2]. The interesting reasons why this is so, and a proper comparison between a nle and rigid-plastic solution for the same problem, is discussed elsewhere [3]. The purpose of this note is to pose the question that if linear JR-type plots are predicted by constant fracture toughness nle solutions, do the same types of plot occur with constant toughness linear elastic cracking? If so, it must have a bearing on the belief still held, it seems, by some people that an increasing JR-Aa curve represents increased resistance to cracking. The note is relevant to a recent paper by Kolednik [4] who discusses the physical meaning of JR curves, and to the paper by Thomason [5] on the very validity of J and J-controlled growth itself.Consider first the simple example of a double cantilever beam LEFM specimen with initial crack length ao. Cracking is stable under displacementcontrol with propagation load X decreasing under increasing load-point displacement. Since the behaviour is globally elastic, all loading-unloading lines Int Journ of Fracture 51 (1991)

show abstract

Stability of cracking

Cited by 72 publications

References 0 publications

Fracture toughness and critical strain energy release rate of dental amalgam

Fracture toughness and critical strain energy release rate of dental amalgam

A double-torsion study of the fracture of polyethersulphone

Linear elastic JR Curves?The fallacy of increased resistance to fracture

Contact Info

Product

Resources

About