Biaxial loading effects on fracture toughness of reactor pressure vessel steel

McAfee, W.J.; Bass, B.R.; Bryson, J.W.; Pennell, W.E.

doi:10.2172/35267

Cited by 15 publications

(5 citation statements)

References 2 publications

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“…The mixed effect of low in‐plane and high out‐of‐plane constraint has received some attention, for example notable experiments were performed in the Oak Ridge National Laboratory 22–26 . The Oak Ridge National Laboratory work consisted of two sets of experiments on cleavage fracture of A533B steel.…”

Section: Introductionmentioning

confidence: 99%

“…It is clear then that there is uncertainty in the effectiveness of biaxial loading on shallow cracks to demonstrate an effect of out‐of‐plane loading. Some researchers believe they found an effect of biaxial loading 22–28 whereas others observed no change 29,30,32 . Because most of the experimental investigations were performed using FPB cruciform specimens in bending, shallow cracks had to be introduced in the specimens which led to a mixed effect of low in and high out‐of‐plane constraint.…”

Section: Introductionmentioning

confidence: 99%

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Reduction of measured toughness due to out‐of‐plane constraint in ductile fracture of aluminium alloy specimens

Mostafavi

Smith

Pavier

2010

Fatigue Fract Eng Mat Struct

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A B S T R A C T It is generally believed that a lower bound on the fracture toughness of a material is obtained from a standard test, particularly in metals where yielding occurs prior to fracture. The understanding is that in such a test the material around the crack tip is highly constrained hence reducing the extent of yielding. In this paper, we report the results of fracture tests where a tensile load is applied to a biaxial aluminium alloy specimen in the direction parallel to the crack front in addition to the fracturing load normal to the crack surface. We show that in this case a lower fracture toughness is measured than that obtained from a standard test. Indeed, for the highest value of tensile load used in our tests the J-integral at fracture was half the value measured in a standard test. It is also shown that the volume of the plastic region can be used to measure the effect of constraint, irrespective of the manner in which the constraint arises. This approach suggests an even lower fracture toughness may be obtained than that measured here in certain loading conditions. a = crack length A = area of the plastic region A c = area of the plastic region at fracture A ref = area of the plastic region at fracture measured in a standard test A 2 = parameter quantifying second and third term of stress relative to the first term in a cracked elastic-plastic body B = biaxiality ratio (dimensionless T-stress) E = elastic modulus F c = corrected fracture load F c = fracture load F T = transverse load (side load)i = the number of tested specimen J = J-integral J c = J-integral at fracture J ref = J-integral at fracture measured in a standard test K I = mode I stress-intensity factors K Ic = mode I fracture toughness measured from a standard test N = total number of specimens tested P f = fracture probability Q = parameter quantifying the deviation of opening stress in a non-standard specimen from a standard specimen Correspondence: M. J. Pavier.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reduction of measured toughness due to out‐of‐plane constraint in ductile fracture of aluminium alloy specimens

Mostafavi

Smith

Pavier

2010

Fatigue Fract Eng Mat Struct

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“…Одним з можливих шляхів пошуку резервів міцності при розрахунках на опір крихкому руйнуванню корпусу реактора є врахування впливу реального двовісного навантаження на береги поверхневої постульованої тріщини в стінці корпусу реактора з врахуванням її глибини. Піонерськими роботами присвячені дослідженню впливу двовісного навантаження, відповідної до постульованих в стінці корпусу реактора конфігурації, на характеристики статичної тріщиностйкості є праці професора Басса [1] в яких було розроблено великогабаритний хрестоподібний зразок на п'ятиточковий згин, що дозволив для реакторних сталей в неопроміненому стані (вихідний матеріал) вивчати одночасно вплив ефекту «коротких тріщин», двовісного навантаження (наближеного до того що реалізується в стінці корпусу реактора) на характеристику тріщиностійкості KJс. Враховуючи велику вартість виготовлення крупногабаритних хрестоподібних зразків і неможливість виконання порівняльних експериментальних досліджень для опроміненого й вихідного матеріалу корпусних реакторних сталей, корейськими [2] та німецькими вченими [3] Зародження тріщини та її зростання контролювали за методом піддатливості, записуючи діаграму навантаження-розкриття берегів тріщини.…”

Section: вступunclassified

Experimental studies of the influence of biaxial bending on the crack resistance of reactor pressure vessel steel

Sydiachenko,

Pokrovskyi

2023

ПТТтаІО

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Background: to assess the residual life of nuclear reactor hulls in Ukraine, normative temperature dependences of the crack resistance of hull steels obtained on standard samples with a deep through crack under plane strain conditions are used. However, it is known that the thickness of the wall of the reactor body is subject to biaxial loading, which affects the value of the crack resistance characteristics. Therefore, in order to substantiate the possibility of lengthening beyond the design resource of VVER-1000 reactor hulls, an experimental study of the effect of biaxial load on the crack resistance characteristics of hull reactor steel 15X2NMFAA is relevant. Objective: development of an experimental technique and investigation of crack resistance under biaxial loading on small-sized samples in the the brittle-ductile transition temperature range of reactor steels. Methods: on the basis of numerical and engineering calculations, a specimen was developed, the corresponding additional equipment for its tests under biaxial loading on a uniaxial servo-hydraulic machine. The influence of biaxial bending on the fracture toughness of reactor steel 15X2NMFAA was experimentally investigated. Results: the results obtained on cruciform specimen are calculated according to the ASTM 1921 standard and plotted on the Master curve (temperature dependence of fracture toughness). The analysis showed that the data on crack resistance obtained on samples with "short" (a/W=0.1...0.2) linear and surface semi-elliptical cracks exceed the upper limit of the confidence interval of the Master curve, and biaxial loading of cruciform specimen reduces crack resistance compared to uniaxial loading.

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“…Applications of these methodologies based on a hydrostatic stress fracture criterion indicated an effect of loadingbiaxiality on fracture toughness, where the conventional maximum principal stress criterion indicated no effect. The ability of stress-strain bused methodologies to predict the biaxial loading effect is also being investigated by the HSST Program [5,12] as well as by other researchers [13].…”

Section: Longitudinal Beamarmmentioning

confidence: 99%

Shallow Flaws Under Biaxial Loading Conditions—Part II: Application of a Weibull Stress Analysis of the Cruciform Bend Specimen Using a Hydrostatic Stress Criterion1

Williams

Bass

McAfee

2000

Journal of Pressure Vessel Technology

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Oak Ridge, Tennessee USA Cruciform beam fracture mechanics specimens-have been developed in the Heavy Section Steel Technology (HSST) Program at Oak Ridge National Laboratory (ORNL) to introduce a prototypic, farfield, out-of-plane biaxial bending stress component in the test section that approximates the nonlinear biaxial stresses resulting from pressurized-thermal-shock or pressure-temperature loading of a nuclear reactor pressure vessel (RPV). Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shallow, surface flaws. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for RPV materials. Two and threeparameter Weibull models have been calibrated using a new scheme (developed at the University of Illinois) that maps toughness data from test specimens with distinctly different levels of crack-tip constraint to a small scale yielding (SSY) Weibull stress space. These models, using the new hydrostatic stress criterion in place of the more commonly used maximum principal stress in the kernel of the 6, integral definition, have been shown to correlate the experimentally observed biaxial effect in cruciform specimens, thereby providing a scaling mechanism between uniaxial and biaxial loading states.

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Biaxial loading effects on fracture toughness of reactor pressure vessel steel

Cited by 15 publications

References 2 publications

Reduction of measured toughness due to out‐of‐plane constraint in ductile fracture of aluminium alloy specimens

Reduction of measured toughness due to out‐of‐plane constraint in ductile fracture of aluminium alloy specimens

Experimental studies of the influence of biaxial bending on the crack resistance of reactor pressure vessel steel

Shallow Flaws Under Biaxial Loading Conditions—Part II: Application of a Weibull Stress Analysis of the Cruciform Bend Specimen Using a Hydrostatic Stress Criterion1

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