Vibration Problems

IN a paper read ore the Institution of Electrical Engineers in London recently Dr. A. J. King considers the vagous ways in which vibration manifests itself, itamely, noise, oration, stress and rotational. The available methods of measuring vibration are dejrtpifeed and their relative merits and Methods of calibrating measur ing app raju ltre given, with an indication of their limits. I suppression of vibration is considered from points of view of what is desirable, how much can be obtained at the source and how much by resilient mountings, attention being given to the effect of ground and source impedance. Practical examples are given of the reductions in vibration which have been achieved in certain cases by improve ments in the source and by resilient mountings. The second part of the paper is concerned with the determination of elastic design data on resilient materials and mountings for use as described earlier for reducing vibration transmission. The limitations of a previous moving-iron-drive resonance-type method are discussed, and the advantages of a moving-coil-drive co-ordinate-potentiometer method are pointed out. The apparatus is described in detail, and results of tests on typical materials and mountings are jfikren and discussed.