This book covers that field of engineering studies which conventionally goes under the name Theory of Machines'. Over the years, knowledge in this area has expanded manifold both in width as well as in depth. This is invariably reflected in the theme and scope of some of the prominent text/reference books published over the last 40 years or so. Departing from traditionally common titles, some of the relatively recent book titles are Applied Kinematics. Mechanics of Machinery, Kinematics and Dynamics of Plane Mechanisms and Synthesis and Analysis of Mechanisms. Details of these titles appear in the Bibliography provided at the end of this book.
Needless to say that in some way, may be in different proportions, these trends should get reflected in our course curriculum. On the analysis side, there is a visible shift of emphasis from graphical to analytical approach. Modern high-speed applications have greatly enhanced the importance of acceleration analysis for accessing the effect of inertia forces in the overall design of machine components. This is further accentuated by the availability of high speed computers.
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Besides accuracy and speed of computations, analytical methods help in establishing motion characteristics (e.g. velocity and acceleration) for large number of configurations of a mechanism (e.g. for different crank positions in an I.C. engine with minimal extra time. This feature enables to establish maximum value of inertia force and corresponding crank angle of rotation, thereby rendering design calculations more rationale. In view of the importance of this area of learning, a separate chapter has been devoted to the analytical methods of velocity and acceleration analysis.
The above comments, however, should not be taken to mean that traditional graphical methods need to be replaced by analytical methods. It is generally believed that graphical methods provide a better insight into the subject matter. This is in fact true. A separate chapter on graphical analysis of velocity and acceleration analysis has, therefore, been included in this book. A practising mechanical engineer is required to design a mechanism that satisfies the prescribed motion characteristics. The synthesis method calls for exposure to type synthesis number synthesis or dimensional synthesis.
An obvious outcome of number synthesis can be seen in the Enumeration of distinct chains of given number of links and degrees of freedom. This aspect has been discussed in the chapter on planar mechanisms. Function and path generation problems involve dimensional synthesis. Coupler curves provide a very useful tool in mechanism synthesis. A separate chapter has been dedicated to the studies on elements of mechanism synthesis in kinematics and it includes discussions on the coupler curves and cognate linkages. In all conventional topics, attempt has been made to present the subject matter in a ommensurate with state-of-the-art presentation in the published literature.
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While teaching dynamic force analysis, a common observation is that the students do not have enough exposure to the application part of D'Alembert's principle. Therefore, in chapters involving dynamic orc e analysis, special emphasis has been laid to explain as to how the problem is converted into an equivalent problem of static equilibrium. Special efforts have been made to explain how positive drive is really achieved through gearing action. Similarly, extra efforts have been made to convey conceptual meaning of interference' of involute gear through the principle of conjugate teeth. Wherever deemed necessary, applications of principle of inversion' and 'instantaneous centre of rotation' have been highlighted.
Throughout the text, special emphasis has been laid on developing conceptual understanding. This will be especially visible in the chapter on governors, cams and gyroscopes. The book is designed to serve as a textbook for undergraduate engineering students studying in mechanical, production and aeronautical streams. The course content is intended to be covered as a two-semester course, requiring about 90 lecture hours. While preparing the manuscript of this book, I had in my mind needs of B.EB.Tech. students of various universities and institutes of higher learning.