The load separation andη
                     
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               development in precracked specimen test recordsdevelopment in precracked specimen test records

Sharobeam, M. H.; Landes, J. D.

doi:10.1007/bf02555184

Cited by 46 publications

(39 citation statements)

References 7 publications

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“…About 10 years later, Sharobeam and Landes [115,116] strictly verified the existence of load separation relationship for ductile materials using detailed experimental investigations and numerical finite element analyses. This laid a solid foundation for the simple J estimation procedure using the g-factor equation approach.…”

Section: Early J Estimation and G-factor Equationsmentioning

confidence: 97%

“…An alternative technique named normalization method was developed to estimate instantaneous crack length directly from the load versus LLD data record. The basis is the principle of load separation [114][115][116] and the key curve method [126,144]. This technique does not require any devices for online monitoring of crack growth, but suggests an individual calibration curve to be used to determine instantaneous crack size.…”

Section: Normalization Data Reduction Techniquementioning

confidence: 99%

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Review of fracture toughness (G, K, J, CTOD, CTOA) testing and standardization

Zhu

Joyce

2012

Engineering Fracture Mechanics

604

126

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Stress intensity factor Energy release rate CTOD CTOA J-integral J-R curve K-R curve ASTM standard a b s t r a c tThe present paper gives a technical review of fracture toughness testing, evaluation and standardization for metallic materials in terms of the linear elastic fracture mechanics as well as the elastic-plastic fracture mechanics. This includes the early investigations and recent advances of fracture toughness test methods and practices developed by American Society for Testing and Materials (ASTM). The review describes the most important fracture mechanics parameters: the elastic energy release rate G, the stress intensity factor K, the Jintegral, the crack-tip opening displacement (CTOD) and the crack-tip opening angle (CTOA) from the basic concept, definition, to experimental estimation, test methods and ASTM standardizing practices. Attention is paid to guidelines on how to choose an appropriate fracture parameter to characterize fracture toughness for the material of interest, and how to measure the fracture toughness value defined either at a critical point or in a resistance curve format using laboratory specimens. The relevant ASTM fracture toughness test standards considered in this paper are E399 for K Ic testing, E561 for K-R curve testing, E813 for J Ic testing, E1152 for J-R curve testing, E1737 for J Ic and J-R curve testing, E1290 for CTOD (d) testing, a combined common test standard E1820 for measuring the three parameters of K, J and d, E1921 for the transition reference temperature T 0 testing and the master curve of cleavage toughness K Jc testing, and E2472 for CTOA testing. The effects of loading rate, temperature and crack-tip constraint on fracture toughness as well as fracture instability analysis are also reviewed.

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Section: Early J Estimation and G-factor Equationsmentioning

confidence: 97%

Section: Normalization Data Reduction Techniquementioning

confidence: 99%

Review of fracture toughness (G, K, J, CTOD, CTOA) testing and standardization

Zhu

Joyce

2012

Engineering Fracture Mechanics

604

126

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“…Among these techniques, the normalization method (Landes and Zhou 1993;Zhou et al 1994;Bernal et al 1995;Bernal et al 1996;Morhain and Velasco 2002) and, more recently, the S pb method (Wainstein et al 2004;Salazar and Rodriguez 2008) have been proven to produce for ductile polymers J R curves in good agreement with those determined by a multi-specimen technique. Both these singlespecimen approaches are theoretically based on the load separation criterion (Ernst et al 1981), whose validity in fracture tests on metals was extensively investigated by Sharobeam and Landes (1991); Sharobeam and Landes (1993). In the work published in 1993 they pointed out that, by using an experimental approach based on the load separation criterion, the crack initiation point, and therefore J Ic , could be indirectly evaluated from the load vs displacement curve recorded during the fracture test, without the necessity to construct the material J R curve.…”

Section: List Of Symbols Amentioning

confidence: 99%

“…In the present work, the applicability of the load separation criterion based procedure proposed by Sharobeam and Landes (1993) in determining the fracture resistance, J Ic , of a toughened polyamide 66 (PA66) was examined both at low (from 0.5 to 50 mm/ min) and moderately high (0.6 m/s) loading rates. At each loading rate explored, the possible influence of the initial crack length to specimen width ratio, a 0 /W , on the results was investigated.…”

Section: List Of Symbols Amentioning

confidence: 99%

On the applicability of the load separation criterion in determining the fracture resistance (J Ic) of ductile polymers at low and high loading rates

2010

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In this work, the applicability of a procedure based on the load separation criterion in determining the fracture resistance (J Ic ) of a rubber modified polyamide 66 (PA66) was analyzed and discussed. In particular, the effects of the testing conditions, with particular reference to geometry and loading rate, on the applicability of the method were investigated. The tests were performed both at low (from 0.5 to 50 mm/ min) and moderately high (0.6 m/s) loading rates, on single edge notched in bending specimens with different initial crack length to width ratios (a 0 /W ), which ranged between 0.3 and 0.7. Among the various findings it is worthwhile to point out that this analysis revealed that the plastic displacement at the end of the blunting process (at fracture initiation) resulted geometry independent. A clear dependence of such a parameter on the loading rate was observed. Further, it was shown that load separation is maintained beyond the blunting phase, as observed in the experiments carried out at low rate. List of symbolsa Crack length ( mm) a 0 Initial crack length ( mm) A pl Area under the load per unit thickness vs plastic displacement (J/m) b Ligament length ( mm) b 0 Initial ligament length ( mm) B Specimen thickness ( mm) C Specimen elastic compliance ( mm/N) C 0 Initial elastic compliance of the specimen ( mm/N) E Young's modulus ( MPa) f Tabulated function (Williams 1987) G Geometry function H Material deformation function J Fracture resistance (J-integral) ( kJ/m 2 ) J bl J at the blunting line ( kJ/m 2 ) J el Elastic part of J ( kJ/m 2 ) J pl Plastic part of J ( kJ/m 2 ) J Ic J at fracture initiation ( kJ/m 2 ) J I,lim J at the point corresponding to the upper limit of the separable blunting region ( kJ/m 2 ) J 0.2 J at 0.2 mm crack extension ( kJ/m 2 ) m Multiplicative coefficient in blunting line equation P Load (kN) P b Blunt notched specimen load (kN) P N Normalized load ( MPa) P p Sharp notched specimen load (kN) 123 106 F. Baldi et al.

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“…2. The load separation concept, developed by Ernst et al (1981) and further investigated by Sharobeam and Landes (1993) and Donoso and Landes (1993) which allows one to calculate the applied J directly from the load-displacement curve for nongrowing cracks.…”

Section: Introductionmentioning

confidence: 99%

A J-integral estimation method for C(T) specimens using the Common Format Equation

2005

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A new J estimation scheme based on the Common Format Equation (CFE) is laid out for Compact Tension (C(T)) specimens. In this context, the CFE constraint factor *, originally given only for the two limits plane stress, and plane strain, is discussed. A nonlinear finite element analysis of the behaviour of blunt notched C(T) specimens with varying crack length was performed. The specimen thickness B has been varied from 3.125 up to 25 mm. Furthermore the special cases plane stress and plane strain have been considered. Considering a linear elastic -ideal plastic material, a limit load analysis has been performed numerically from which * has been obtained as a function of the ligament-to-thickness-ratio B/b. The J -integral as a function of the load line displacement v has been determined for isotropic, nonlinear hardening material, where J has been calculated using its definition as contour or surface integral, respectively. It is shown that if the obtained J (v) curves are normalized according to the Common Format Methodology, all curves fall approximately into one single curve. This allows to estimate J (v) curves for C(T) specimens using the CFE.

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The load separation andη pl development in precracked specimen test recordsdevelopment in precracked specimen test records

Cited by 46 publications

References 7 publications

Review of fracture toughness (G, K, J, CTOD, CTOA) testing and standardization

Review of fracture toughness (G, K, J, CTOD, CTOA) testing and standardization

On the applicability of the load separation criterion in determining the fracture resistance (J Ic) of ductile polymers at low and high loading rates

A J-integral estimation method for C(T) specimens using the Common Format Equation

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