Service Failures of Railway Materials

Service failures were known to occur even before ushering in of machine age but there was no proper understanding of the underlying phenomenon and at best the attempt to overcome them lay in redesigning the components merely by thickening those sections irrespective of poor quality of material or inadequate sectional strength. In the late twenties, however, with springing up of chemical and metallurgical laboratories and with better understanding of Fatigue phenomenon which is the chief fact or underlying a vast majority of service failures, greater interest was taken in the study of performance and failures of components in service

Noncommutative generalizations of theorems of Cohen and Kaplansky

This paper investigates situations where a property of a ring can be tested on a set of "prime right ideals." Generalizing theorems of Cohen and Kaplansky, we show that every right ideal of a ring is finitely generated (resp. principal) iff every "prime right ideal" is finitely generated (resp. principal), where the phrase "prime right ideal" can be interpreted in one of many different ways. We also use our methods to show that other properties can be tested on special sets of right ideals, such as the right artinian property and various homological properties. Applying these methods, we prove the following noncommutative generalization of a result of Kaplansky: a (left and right) noetherian ring is a principal right ideal ring iff all of its maximal right ideals are principal. A counterexample shows that the left noetherian hypothesis cannot be dropped. Finally, we compare our results to earlier generalizations of Cohen's and Kaplansky's theorems in the literature.Comment: 41 pages. To appear in Algebras and Representation Theory. Minor changes were made to the numbering system, in order to remain consistent with the published versio

Investigations On Strength Analysis Of Lap Joints For Aluminum- Epoxy Composite Plates Using Finite Element Method With Experimental Verification

In this dissertation, the mechanical behaviour of 2-bolted single-lap Aluminum glassfiber composite plate with high strength bolts is investigated, both analytically and experimentally. A detailed 3D non-linear FE model of composite bolted joints has been developed. The model replicates with good agreement the experimental tensile tests up to the point where bearing damage occurs and reproduces the joint behaviour correctly. The evolution of contact during the test is studied showing a correlation with the joint stiffness. Using the developed FE model, the distribution of the stress components around the holes of the composite joints is studied together with the effects of hole clearance and position of bolts. The stress along the fibres is identified as the critical stress component and the compressive fibre failure of the 0° oriented plies as the start of the bearing damage. The 0° oriented plies in the cylindrical part of the hole are found to be the plies carrying the bearing load. Increasing clearance reduces the extent of the bolt shank-hole contact and leads to higher stresses and lower joint stiffness. The 45° and -45° oriented plies are found to have a key role in the joint bearing strength and shear-out failure