Micromechanics and fatigue crack growth in an alumina-fiber-reinforced magnesium alloy composite

Davidson, D. L.; Chan, Kwai S.; McMinn, A.; Leverant, G. R.

doi:10.1007/bf02666671

Cited by 17 publications

(5 citation statements)

References 10 publications

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“…Experimental support for the proposed approach is presented in Fig. 8, taken from [7], which shows that crack growth data of the ZE41A composite in the 0", 22.5", and 45' fiber orientations can be correlated with that of the matrix in terms of equation (1 7).…”

Section: Da/dn = C[(e/e)*'ak]"mentioning

confidence: 98%

“…The MMCjCRK program has been used to examine the relationships of fracture mechanism and crack growth rate in the ZE4lA composites with alumina fibers in the 0", 22.5" and 45" orientations [7]. The inputs to the MMCjCRK code used for the crack growth calculations are shown in Table 1.…”

Section: Model Applicationmentioning

confidence: 99%

“…It should be noted that the observed fracture mechanism in the 22.5" and 45" composites were more complicated than those in the 0 fiber composite or predicted by the model. The sequence of fracture events for the 45" fiber composite [7] was propagation of the main crack through the matrix, approximately perpendicular to the fibers until the next fiber was reached; the crack then deflected to propagate parallel to the fiber, either in the matrix or along the interface, for a distance of 2-4 times the fiber spacing, followed by fiber failure. The calculations shown in Fig.…”

Section: Model Applicationmentioning

confidence: 99%

“…have revealed complex interactions between a crack and the fiber, matrix, and the matrix/fiber interface in failure of these materials. Some of the often observed fracture micromechanisms under cyclic loading include fiber fracture [ 1-81. the propagation of a fiber crack into the matrix [7], the propagation of an interface crack along the matrix/fiber interface [l-81, fiber shielding [7], crack deflection at fibers [l-81, and bridging of the crack surfaces by unbroken fibers [9-111. Because of these complex interactions, the properties of the matrix, fiber, and their interface are expected to exert significant influences on the fatigue behavior of the composites.…”

Section: Introductionmentioning

confidence: 99%

“…As a demonstration of its capabilities, the model will be applied for predicting the crack growth behavior of an Mg-alloy composite with 35 vol.% alumina fibers (20 pm diameter). The matrix of the composite is ZE41A, an Mg alloy containing (in wt%) 4.25% Zn, 0.5% Zr, and 1.25% rare earths [7].…”

Section: Introductionmentioning

confidence: 99%

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A Fatigue Crack Growth Model for Fiber‐reinforced Metal–matrix Composites

Chan

1990

Fatigue Fract Eng Mat Struct

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Abstrpct-A fracture-mechanics based model is proposed for fatigue crack growth in fiber-reinforced metal-matrix composites (MMCs). The model incorporates most of the fracture micromechanisms commonly observed in fiber-reinforced MMCs, including (1) formation of microcracks ahead of the crack tip by either fiber fracture or interface decohesion, (2) interactions of the main crack tip with fibers and microcracks, (3) linkage of the main crack with microcracks, and (4) crack deflection by fibers. Statistical variations of fiber or interface strength are also considered. The essential feature of the model is to compute the changes in the local stress intensity due to various fracture mechanisms; the local stress intensity is then utilized to predict crack growth rate in MMCs via an elastic modulus normalization procedure. Application of the model to predicting crack growth in an alumina fiber Mg-alloy composite is presented. NOMENCLATURE a,, = interaction matrix of a deflected crack A(B,,; a t ) = a matrix of complicated trigonometric functions of Oi and aI B(B,; aI ) = a matrix of complicated trigonometric functions of 8, and a, C = constant in crack growth equation D = fiber diameter E = Young's modulus of composite El = Young's modulus of fiber Em = Young's modulus of matrix FK = interaction functions of main crack and microcracks F,, = interaction functions of main crack with fiber GI = shear modulus of fiber G, = shear modulus of matrix AK = applied stress intensity range I =identity matrix AKF = stress intensity ranges of the microcrack AKL = local stress intensity range AKP = stress intensity range due to microcrack interaction, fiber shielding, or crack deflection K, = stress intensity factor in the lth mode mk = Weibull constants I = segment length n =constant in crack growth equation r = radial distance from the crack tip R , = radial distance of microcrack from crack tip R, = average fiber spacing s =half length of microcrack uk = standard uniformly distributed random numbers Vf = volume fraction of fibers in composite a, = inclination angle of microcrack with respect to the X axis B = angular position from the crack tip 8, = angular position of microcrack from crack tip u,, = stress tensor UP, = minimum values of fracture strength p, , p2 =complex characteristic roots 171 172 K. S. CHAN u; = maximum values of fracture strength AuP, ASP = interaction stresses of main crack with microcracks u,,, u , ) , u ,~ = Cartesian components of stresses u:, = debonding strength of matrix/fiber interface u:, = longitudinal fracture strength of fiber u:, = interfacial shear strength q5 = angle of deflection I, = debonded length I, = distance of crack tip from fiber interface a = angle between fiber and stress axis j = angle between crack normal and stress axis 6 = bi-elastic constant

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Section: Da/dn = C[(e/e)*'ak]"mentioning

confidence: 98%

Section: Model Applicationmentioning

confidence: 99%

Section: Model Applicationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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