M.Ing. / Measurement of acceleration is of importance for several applications such as impact tests and navigation. The design and manufacture of a symmetrical piezoresistive accelerometer, which can measure accelerations up to 60 000 g, are presented in this work. Various accelerometers are discussed and compared. The design of an accelerometer is an interdisciplinary activity which requires knowledge of the mechanical and electronic properties of materials as well as electronic signal processing. Computer design aids such as finite element analysis and semiconductor process modelling are used in this work to optimize first order designs. Since accelerometers with large dynamic range must be small in size in order to cause the minimum disturbance of the measurand, micromachining of silicon is used to manufacture extremely small devices. A substantial part of this work deals with the different materials and methods used in the manufacturing process. Since there is an inevitable spread in the parameters of the accelerometers, each one requires calibration. A test facility was developed to test and calibrate accelerometers up to 20 000 g. Because shock impulse response is determined by the test facility, a Fourier-transform is used to compute the frequency response of the accelerometer. The result of this work is the development and manufacture of an accelerometer with a mass of approximately 1 mg. The extremely small size and mass makes it very useful for measuring high accelerations.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:10561 |
| Date | 10 April 2014 |
| Creators | Coetzer, Paul Jacobus |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Johannesburg |
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