Finite crack kinking and T-stresses in functionally graded materials

Becker, T.L.; Cannon, R.M.; Ritchie, Robert O.

doi:10.1016/s0020-7683(00)00379-6

Cited by 72 publications

(27 citation statements)

References 23 publications

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“…In all three cases the crack moves with a constant velocity of 725 m/sec, 620 m/sec and, 560 m/sec for 8 = 0, 30-and, 45-, respectively. The reduction in the crack-tip velocity with increasing angle (8) can be explained by looking at the rate of change of local stress intensity factor with propagation distance as given by equation (21).…”

Section: Crack Propagation Isochromaticsmentioning

confidence: 99%

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Mixed Mode Dynamic Fracture in Particulate Reinforced Functionally Graded Materials

Jain

Shukla

2006

Exp Mech

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A detailed analytical and experimental investigation is presented to understand the dynamic fracture behavior of functionally graded materials (FGMs) under mode I and mixed mode loading conditions. Crack-tip stress, strain and displacement fields for a mixed mode crack propagating at an angle from the direction of property gradation were obtained through an asymptotic analysis coupled with a displacement potential approach. This was followed by a comprehensive series of experiments to gain further insight into the behavior of propagating cracks in FGMs. Dynamic photoelasticity coupled with high-speed photography was used to obtain crack tip velocities and dynamic stress fields around the propagating cracks. Birefringent coatings were used to conduct the photoelastic study due to the opaqueness of the FGMs. Dynamic fracture experiments were performed using different specimen geometries to develop a dynamic constitutive fracture relationship between the mode I dynamic stress intensity factor (K ID ) and crack-tip velocity ( : a ) for FGMs with the crack moving in the direction of increasing fracture toughness. A similar : a -K ID relation was also obtained for matrix material (polyester) for comparison purposes. The results obtained show that crack propagation velocities in FGMs were about 80% higher than the polyester matrix. Crack arrest toughness was found to be about 10% lower than the value of local fracture toughness in FGMs.

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Section: Crack Propagation Isochromaticsmentioning

confidence: 99%

“…In contrast to extensive availability of literature on stationary crack problem in FGMs [7][8][9][10][11][12][13][14], only a few studies on dynamic fracture of FGMs have been reported in literature. Jain and Shukla developed the explicit expression for the stress fields present around propagating crack-tip in FGMs [15].…”

Section: Introductionmentioning

confidence: 99%

Mixed Mode Dynamic Fracture in Particulate Reinforced Functionally Graded Materials

Jain

Shukla

2006

Exp Mech

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“…Two other numerical investigations are relevant to the present work, Becker et al [5] and Kim and Paulino [6], both of which include the effect of the T-stress (the nonsingular term acting in a direction parallel to the crack plane in the asymptotic expansion for stresses) in their finite element simulations. For homogeneous materials, the T-stress plays an important role in their fracture in absence of localized yielding, or when the size of the plastic zone is small relative to the process zone [7].…”

Section: Introductionmentioning

confidence: 99%

“…The role of the T-stress in the fracture behavior of FGMs is less understood. Becker et al [5], using the maximum energy release rate criterion, found that for FGMs the magnitude of the T-stress is, on average, greater than the one corresponding to homogeneous materials having the same geometry. It was also found that, in contrast to homogeneous materials, for kink angles that maximize the energy release rate the mode II stress intensity factor, K II , is not necessarily zero.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study of Mixed Mode Crack Initiation and Growth in Functionally Graded Materials

Abanto-Bueno

Lambros

2006

Exp Mech

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Quasi-static mixed mode crack initiation and growth in functionally graded materials (FGMs) was studied through fracture experiments on polymerbased FGMs manufactured by selective ultraviolet irradiation of poly(ethylene carbon monoxide)-a photo-sensitive copolymer that becomes more brittle and stiffer under ultraviolet irradiation. The objective of the study was to determine whether crack kinking criteria for homogeneous materials, e.g., maximum hoop stress criterion, also hold for FGMs. Single edge notched tension specimens with different spatial variations of Young's modulus, failure stress and failure strain, were tested. Near tip mode mixity was introduced either by inclining the crack to the remote loading direction, as in the case of homogeneous materials, or to the direction of material gradient, or both. A full-field digital image correlation technique was used to measure in real-time the displacement field around the crack tip while it propagated through the graded material, and to extract the fracture parameters of stress intensity factor K I and K II , and the T-stress. It was found that the nonsingular T-stress term in the asymptotic expansion for stresses plays a very important role in accurately measuring fracture parameters. It was also found that the maximum tangential stress criterion can be applied to the case of FGMs to predict crack kinking provided that the effect of the T-stress is accounted for and the process zone size is small compared to the intrinsic material gradient length scale. However, for accurate crack path prediction at a length scale comparable to the material gradient, detailed material property information is required. In general, the crack will propagate towards a region that exhibits less fracture toughness, but, unlike the case of homogeneous materials, along a path where K II is not necessarily equal to zero.

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“…Jin and Noda (1994) showed that the inverse square root singularity at a crack-tip still prevails in FGMs provided that Young's modulus and Poisson's ratio are continuous and piecewise continuously differentiable, which is an extension of Eischen's result (Eischen, 1987) for nonhomogeneous materials with sufficiently smooth material properties. Gu and Asaro (1997) and Becker et al (2001) studied crack deflections in FGMs. Jin and Batra (1996) and Anlas et al (2002) investigated the K-dominance problem in FGMs.…”

Section: Introductionmentioning

confidence: 99%

On the Moving Griffith Crack in a Nonhomogeneous Orthotropic Strip

Guo

2005

Int J Fract

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A finite crack with constant length (Yoffe type crack) propagating in the functionally graded orthotropic strip under the plane loading is investigated by means of the Schmidt method. By using the Fourier transform and defining the jumps of displacement components across the crack surface as the unknown functions, two pairs of dual integral equations are derived. To solve the dual integral equations, the jumps of the displacement components across the crack surface are expanded in a series of Jacobi polynomial. Numerical examples are provided to show the effects of material properties, the thickness of the functionally graded orthotropic strip and the speed of the crack propagating upon the dynamic fracture behavior.

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Finite crack kinking and T-stresses in functionally graded materials

Cited by 72 publications

References 23 publications

Mixed Mode Dynamic Fracture in Particulate Reinforced Functionally Graded Materials

Mixed Mode Dynamic Fracture in Particulate Reinforced Functionally Graded Materials

An Experimental Study of Mixed Mode Crack Initiation and Growth in Functionally Graded Materials

On the Moving Griffith Crack in a Nonhomogeneous Orthotropic Strip

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