Single-crystal aluminas are being considered for use in the manufacture of prosthetic heart valves. To characterize such materials for biomedical application, subcritical crack growth by stress corrosion (static fatigue) and by cyclic fatigue has been examined in sapphire along (1100) planes in 24 degrees C humid air and 37 degrees C Ringer's solution (the latter as a simulated physiological en...

The authors discuss fatigue strength of welded rib-to-web junctions at the deck supports with reference to redecking of the Williamsburg and the Bronx-Whitestone bridges, where low available depth necessitated the use of special details, and recommend the use of the “modified nominal stress approach” for the design of such connections. However, experience with thousands of existing orthotropic ...

An assessment of the effects of microstructure on room temperature fatigue crack initiation and short crack propagation in a Ni-base superalloy is presented. The assessment was carried out on microstructural variants of U720Li, including as-received U720Li, U720Li-LG (large grain variant) and U720Li-LP (large intragranular coherent γ′ variant). Fatigue tests were carried out at room temperature...

Fatigue cracking in metallic aircraft structure often originates at fastener holes and can be detected using the nondestructive inspection technique of bolt-hole eddy-current (BHEC) testing. BHEC testing is based on detection of a disturbance in the induced current or magnetic field caused by a surface-breaking crack in the bore of the hole. However, if the surface of the hole contains benign m...

Standard asphalt mixtures for road infrastructures consist of natural aggregate and bitumen. A number of research efforts have successfully investigated the possibility of replacing the conventional aggregate skeleton with industrial by-products such as slag originating from steel production process. However, little is known on the effect of steel slag on the mixtures functional performance and...

The total fatigue life of a brace in an offshore jacket structure is conventionally considered in four parts. N 1 is the number of cycles to initiate the first discernible surface cracking as noted by any available method. N 2 is the number of cycles to detect surface cracking by visual examination without the use of crack enhancement or optical aids. N 3 is the number of cycles until the first...

The effects of the bond coat species on the delamination or fracture behavior in thermal barrier coatings (TBCs) was investigated using the yclic thermal fatigue and thermal-shock tests. The interface microstructures of each TBC showed a good condition without cracking or delamination after flame thermal fatigue (FTF) for 1429 cycles. The TBC with the bond coat prepared by the air-plasma spray ...

Several key fracture-mechanics parameters associated with the onset of subcritical and critical cracking, specifically the fracture toughness, crack-resistance curve, and fatigue threshold, have recently been reported for the superelastic alloy Nitinol, in the product form of the thin-walled tube that is used to manufacture several biomedical devices, most notably endovascular stents. In this s...

To clarify the internal fatigue crack generation in a Ti-Fe-O (near a-type) alloy, microstructures, internal fatigue crack initiation sites, and dislocation structures in samples fractured during high-cycle fatigue tests at liquid nitrogen temperature were studied. The alloy contained two kinds of elongated a-phase microstructures, i.e., recovered a grains and recrystallized a grains. Untested ...