Consider a uniform shaft of negligible mass rigidly fixed at its upper end and carrying a disc at its lower end, as shown in Fig. If the disc is given a twist about its vertical axis and then released, it will start twisting and untwisting about the axis, which is known as torsional vibrations. Let,
Natural Frequency of Free Torsional Vibrations Read More »
Critical or whirling or whipping speed is the speed at which the shaft tends to vibrate violently in the transverse direction. In other words, the speed at which resonance occurs are known as the critical speed. At critical speeds, the amplitude of vibration of rotors is excessively large and a large amount of force is
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In this section, we introduce two additional features of SQL: the CREATE ASSERTION statement and the CREATE TRIGGER statement. Before discusses CREATE ASSERTION, which can be used to specify additional types of constraints that are outside the scope of the built-in relational model constraints (primary and unique keys, entity integrity, and referential integrity) that we
Specifying Constraints as Assertions and Actions as Triggers Read More »
Types of vibration may be classified according to : the actuating force on the body, and the stresses in the supporting medium, as shown in image. According to the Actuating Force Free or Natural Vibrations If the periodic motion continues after the cause of original disturbance (initial displacement) is removed, then the body is said
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Since most of the vibrating system follow harmonic motion (SHM), therefore it is essential to have proper understanding of SHM related basic concepts. A body is said to have simple harmonic motion (SHM), if it moves or vibrates about a mean position such that its acceleration is always proportional to its distance from the mean
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SQL has a number of additional features that we have not described in this chapter but that we discuss elsewhere in the book. These are as follows: we will present the following additional SQL features: various techniques for specifying complex retrieval queries, including nested queries, aggregate functions, grouping, joined tables, outer joins, and recursive queries;
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Any motion which repeats itself after an interval of time is called vibration or oscillation or periodic motion. All bodies possessing mass and elasticity are capable of producing vibrations. Vibration problems, in practice, occur wherever there are rotating or moving parts in a machinery. The study of vibration is concerned with oscillatory motions of the
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Balancing machines are used to: Determine whether the rotating parts of a machine is completely balanced or not, Check the static dynamic balancing of rotating parts, Determine the next extent to which balancing is done (in case of unbalanced system). Type of Balancing Machines Three types of balancing machines are: Static balancing machines These machines
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