Fatigue crack growth is examined in P/M 2124 aluminum alloys reinforced with SiC particles (SiCp) and whiskers (SiCw) over a wide spectrum of growth rates from 10 to 10 m per cycle. Effects of aging treatment, orientation of crack growth direction with respect to the rolling direction, mean stress (or stress ratio), and reinforcement volume percent on the fatigue crack growth threshold are inve...

As a first step towards a new crack healing methodology for cyclic loading, this paper examines two promising crack-tip shielding mechanisms during fatigue of a microcapsule toughened epoxy. Artificial crack closure is achieved by injecting precatalyzed monomer into the crack plane to form a polymer wedge at the crack tip. The effect of wedge geometry is also considered, as dictated by crack lo...

Fatigue crack growth is a complex process that involves interactions between many elements ranging across several length scales. This work provides an in-depth, experimental study of fatigue crack growth and the relationships between four of these elements: strain field, microstructure, crack path, and crack growth rate. Multiple data sets were acquired for fatigue crack growth in a nickel-base...

Tensile performance of textile reinforced inorganic matrix composites strongly depends on the matrix-to-fabric bond strength, that is weak chain in system. In this work, we investigate role multi-walled carbon nanotubes (MWCNT) dispersion an amorphous silica nano-coating for AR-glass and fabric Textile Reinforced Mortar (TRM) composites. Two lime mortars are considered at 56-day curing. Compara...

In this paper an analytical crack propagation scenario is proposed which assumes that a crack propagates in the tooth root in both the crack depth direction and the tooth width direction, and which is more reasonable and realistic for non-uniform load distribution cases than the other presented scenarios. An analytical approach is used for quantifying the loss of time-varying gear mesh stiffnes...

Crack tip shielding phenomena, whereby the "effective crack-driving force" actually experienced at the crack tip is locally reduced, are examined with reference to fatigue crack propagation behavior in metals, composites and ceramics. Sources of shielding are briefly described in terms of mechanisms relying on the production of elastically constrained zones which envelop the crack (zone shieldi...

* Corresponding author; Email: [email protected] ABSTRACT An important task in mixed-mode fracture analysis and prediction is the simulation of crack growth under mixed-mode conditions. To complete such a task, one must have (a) a computer code capable of handling the kinematics of general crack growth and determining the stress and deformation states during crack growth, and (b) a fracture crit...

A Zener±Stroh crack is formed by coalescing a dislocation pileup and therefore is a net dislocation loaded crack. In this paper, the interaction between a Zener±Stroch crack and surrounding cylindrical ®bers in a ®ber-reinforced composite material has been investigated. The crack is located in the matrix and near a ®ber, while the in ̄uence of other ®bers on the crack is considered through the t...

The problem of fatigue-crack-growth in a rotating disc at different crack orientation angles is studied by using an automated numerical technique, which calculates the stress intensity factors on the crack front through the three-dimensional finite element method. Paris law is used to develop the fatigue shape of initially semi-elliptical surface crack. Because of needs for the higher mesh dens...

Understanding the fatigue crack growth phenomenon in railheads requires a study of driving forces such as the crack tip opening and sliding displacements, under repeated rolling contact. Finite element simulations, allowing elastic-plastic deformation, and mixed-mode crack growth laws were utilized to demonstrate that the fatigue crack growth rates display a minimum after a finite amount of cra...