Various Types Of Transducers Research Articles

Recognition of defects from impact generated surface waves on the rim of a railroad wheel

Ultrasonic surface waves have been used to detect thermal cracks on the rim of a railroad wheel. In this paper it is pointed out that surface waves may alternatively be generated by an impact on the rim of the wheel. Several circuits of such waves around the rim can be recognized in the first few milliseconds, after impact, of the signal from a microphone in proximity to the rim or an accelerometer in contact with the wheel. Reflections from cracks can also be recognized. Experimental results were obtained using a ball bearing impact and various types of transducers as receivers. Time domain signals resemble seismograms from which the wave velocity can be calculated. This velocity is in approximate agreement with the theory of surface wave propagation on the edge of a plate. Some developments in this theory will also be presented. The significance of the work lies in the potential for adding surface wave recognition algorithms to an Acoustic Signature Inspection System. [Work supported by Association of American Railroads.]

Spectrum analysis—a diagnostic tool for high speed rotating machinery

The role of the spectrum analyzer as a too] in the location of problem areas is finding greater acceptance in the field of high-speed rotating machinery. Its use as a diagnostic instrument has been limited due to an inadequate understanding of the various signals. To achieve a better understanding of the signed analysis of the various types of transducers and their effect on signature analysis is discussed. The development of data banks to enhance the understanding of various types of signals is described. This data bank is developed by isolating individual problems and recording their signature patterns. These signature patterns can be used both visually or programed for computer matching. In this manner the spectrum analyzer can be used as on line diagnostic system. Test patterns and actual field tests are described to show the impact that such a system would have when combined with performance data as a diagnostic tool.

Development of Instrumentation for Use in Nuclear Environments

The nuclear enviroment to be encountered in testing and operating nuclear rocket engines makes the development of reliable instrumentation imperative. A limited program of testing various types of transducers has been undertaken at LASL. A description of the methods and facilities used is followed by detailed descriptions of tests carried out at LASL on various types of pressure-actuated devices. Techniques which may prove effective in improving instrmuent reliability are mentioned, and plans for further research and development in this area are discussed. In conclusion, the nature and scope of the problem are again referred to, with emphasis being made on the need for a better definition of the problem and a greater effort toward its solution.

Phonocardiography: I. General principles and problems of standardization ∗

The general laws of auscultation and the basic principles and scope of phonocardiography are analyzed and discussed with particular reference to instrumentation. The characteristics and responses of the various types of transducers (microphones), equalizer or filter circuits, amplifiers, and recording oscillographs are presented; they must be known for proper clinical application of phonocardiography.

Electric transducers for automatic weighing

Electric transducers are designed for use with mechanical scales to obtain automatic weighing control. The advantages and disadvantages of the various types of transducers are given to assist the engineer in making the proper design for any special weighing system.