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...

15. Supplementary Notes Project performed in cooperation with the Texas Department of Transportation and the Federal Highway Administration. Project Title: Implementation of Automated Pavement Distress Rating Systems 16. Abstract This paper presents the image-processing algorithm customized for high-speed, real-time inspection of pavement cracking. In the algorithm, a pavement image is divided ...

Fatigue crack initiation and early short crack propagation behaviour in two microstructural variants of a recently developed Low Solvus, High Refractory (LSHR) disc superalloy at room temperature has been investigated by three-point bending with replication procedure. The results shows that fine gained (FG) LSHR possesses higher fatigue life due to its better crack initiation resistance, limite...

concrete is one of the most widely used materials in construction industry. many large and important structures such as power plants, bridges, dams and buildings employ concrete as main material. propagation of crack is considered one of the main reasons in failure of concrete structures. the process of formation and crack growth is one of the major and complex issues in concrete, because concr...

Coherent twin boundaries (CTBs) in nano-twinned materials could improve crack resistance. However, the role of the CTBs during crack penetration has never been explored at atomic scale. Our in situ observation on nano-twinned Ag under a high resolution transmission electron microscope (HRTEM) reveals the dynamic processes of a crack penetration across the CTBs, which involve alternated crack ti...

Experimentally determined T ε and CTOA resistance curves were used to simulate numerically, stable crack growth and the ensuing crack linkup in 0.8 mm thick 2024-T3 aluminum tension specimen with multiple site damage (MSD) subjected to monotonically/cyclically increasing loading. The T ε integral correctly predicted the crack growth and linkup history as well as the onset of rapid fracture in M...

in this paper, the problem of calculating the stress intensity factor (sif) for an orthotropic thick-walled cylinder with a small radial crack subject to internal pressure is considered. the crack is assumed to be an edge crack on the external radius of the cylinder. the stress intensity factor is calculated by superposition of an uncracked cylinder with uniform stress distribution and a cylind...

The corrosion fatigue crack growth characteristics of small (>35pm) surface and corner cracks in aluminum alloy 7075 is established. The early stage of crack growth is studied by performing in situ long focal length microscope (500X) crack length measurements in laboratory air and 1% NaCl environments. To quantify the “small crack effect” in the corrosive environment, the corrosion fatigue crac...

Initial cracks occur in high strength concrete sleepers for various reasons, such as shrinkage and wrong curing and long lifetime of over 50 years of sleepers. These cracks may lead to complete failure of the structure. In order to more accurately design the sleepers, fracture mechanics (not strength of materials) should be incorporated. In order to achieve this purpose, it is important to fore...

Compositionally graded glass-filled epoxy sheets with edge cracks initially along the gradient are studied under dynamic loading conditions. Specimens with monotonically varying volume fraction of reinforcement are subjected to mixed-mode loading by eccentric impact relative to the crack plane. The optical method of Coherent Gradient Sensing and high-speed photography are used to map transient ...