Fatigue crack growth analysis of a reinforced cylindrical shell under random loading

In this paper, fatigue crack growth analysis and reliability evaluation of a reinforced cylindrical shell subjected to random loading have been studied. At first, random loading is extracted from an experimentally obtained power spectral density curve. Then, stress analysis of the shell is carried out using Abaqus ® (ABAQUS Inc., Palo Alto, CA, USA) standard code with the aid of a shell‐to‐solid submodelling technique, and the critical positions susceptible of crack nucleation are determined. Then, the fatigue crack propagation is simulated three‐dimensionally in these regions using the Zencrack ^® software (Zentech International Ltd, London, UK), and the fatigue life and reliability are calculated using the central limit theory. For the evaluation of fatigue life of the full‐scale structure, a procedure of fatigue crack growth and linking up of the two adjacent cracks emanating from critical rivet holes is outlined under random cyclic loading. Using stochastic analysis, closed‐form relations are derived for the probability of failure and reliability.     

Appearance of a cavernous hemangioma in the cerebral cortex after a biopsy of a deeper lesion

Cavernous hemangiomas are vascular malformations that can occur throughout the central nervous system. In certain patients, multiple lesions are known to occur. We present a patient with multiple cavernous hemangiomas who had a computed tomography-guided biopsy of a deep parieto-occipital lesion through a burr hole. Several passes of a biopsy needle were used. During a 5-year interval, the patient developed a new lesion directly under the burr hole on the cortical surface. The new lesion appears to have occurred from the implantation and growth of a cavernous hemangioma secondary to the biopsy.     

Effect of carbon deposition on the activity of steam reforming catalysts

The activity of supported nickel used to catalyse the steam reforming of propylene has been found to be both increased and decreased by carbonisation of the catalyst. Increased activity is observed at temperatures between ca 650 and 375°C, and is suggested to result from the mechanism of carbonisation, which causes increased metal area and increased activity. At high temperatures (> ～ 650°C) and at low temperatures (< ～ 375°C), where a different mechanism of carbonisation results in encapsulation of metal, carbon formation poisons the catalyst. The kinetics of reaction have been measured over a catalyst which has attained steady-state: they indicate that the overall kinetics are influenced by carbon deposition on the catalyst.