Thermal stresses during electro-chemical spark machining
The high temperature distribution generated during electro-chemical spark machining (ECSM) results in large localised thermal stresses in a very small heat affected zone. These thermal stresses can lead to micro-cracks and a decrease in strength and fatigue life of the components. A finite element model is developed to estimate the temperature distribution and thermal stresses due to a single spark (Gaussian distributed heat flux) and within the zone of influence of a single spark. Firstly, the finite element based (FEM) code is developed to estimate temperature distribution in the workpiece due to a single spark and, based on this temperature distribution, thermal stresses are calculated. Thermal stress analysis shows high temperature gradient zones and the regions of large stresses where, sometimes, they exceed the material yield strength.
An introduction to finite element analysis
These three books represent a spectrum of hard-back offerings for fluid mechanicians interested in the finite element (FE) method. The first is not, of course, focused on fluids but is an introduction to the method. The second book is a complete text devoted to finite elements and fluids in general. Finally, the third is a oontinuation of a series and follows from the 1976 Second International Conference on Finite Elements in Flow Problems. In their book Norrie and de Vries have focused on working ‘from the particular to the general’ with a view toward developing ‘a basic understanding of the finite element method rather than providing a comprehensive coverage of its many applications’. The first chapter outlines the basic concepts of the finite element method, while Chapter 2 uses a specific example of a variational formulation for heat flow in two-dimensions to show how things go together when one solves a particular problem. The description and examples of the formulation of the matrices is particularly good. However, the variational formulations are introduced without any justification. A brief physical interpretation would have helped considerably. Chapters 3 to 6 cover computer programming, boundary conditions, various elements, operations on the system of element equations, and aspects of computation. These early chapters are excellent for beginners and give even finite element aficionada good concrete examples. The programs and worked-out examples are very helpful to the learning process. This section of the text makes it a worthwhile complement to the traditional FE texts in one’s library (for example, Norrie and de Vries’ earlier book or those by Huebner and Zienkiewicz). The remainder of Norrie and de Vries’ book is basically descriptive andoften qualitative, a completely different thrust from the early chapters. Chapter 7 on variational calculus includes a good discussion of the required order of trial functions. Chapter 8 describes convergence, completeness, and conformity, but does not demonstrate how accurate actual computations are, i.e. there are no comparisons of computed and analytical solutions. Chapter 9 on elements and their properties is a routine description, but gives only a cursory outline of the use of the important isoparametric elements. Chapter 10 on equation solvers and programming techniques is a good description of what is available and the merits of each method. Again, direct comparisons of accuracy or speed from actual example computations are missing. The selected applications of Chapter 1 1 are valuable because the formulation and matrix set-ups are clearly laid out. Unfortunately, the currently dominant weighted-residual methods are discussed relatively briefly and not until Chapter 12. In sum, the greatest value of the Norrie and de Vries book lies in the detailed
Mutiny Echoes: India, Britons, and Charles Dickens's A Tale of Two Cities
This essay asks what, if any, import the Indian ““Mutiny”” of 1857 had on A Tale of Two Cities (1859), Charles Dickens�s fictionalized account of the French Revolution. Begun shortly after the Indian uprising started, Dickens�s historical novel appears studiously to avoid any mention of events on the Indian subcontinent, even though these events preoccupied and enraged the author. Few scholars have attended to the question of A Tale of Two Cities and the ““Mutiny,”” but when they have, scholars have looked for analogies between India and Dickens�s account of the French Revolution. In this essay, by contrast, I examine A Tale of Two Cities in a larger context——of Britons9 response to the Uprising, of Dickens9s short stories and essays in Household Words in the years before the ““Mutiny”” and immediately after, of Dickens9s disenchantment with aspects of British culture, and of his need to articulate a national identity grounded in action. I argue that the events in India were the match that ignited Dickens9s already established midcentury interests in national identity, nobility, and masculine heroism. I do not wish to suggest that A Tale of Two Cities is an Indian ““Mutiny”” novel, but rather that it is a novel about the ““Making of Britons,”” an important endeavor for an author who was intensely dissatisfied with the Britain that he saw around him.