Harsh-environment MEMS temperature sensors for aircraft bearing health monitoring applications
Abstract
Bearings are among the most important components in a wide variety of commercial and defense applications including aircraft, wind mills, automotive engines and others. Diagnosis of bearing failure remains an unsolved issue today due to the inability to accurately and continuously monitor critical failure signals. Although monitoring of a bearing's acceleration has been accomplished, it has been shown that a bearing's temperature is a much safer indicator of its health status. For example, when small cracks or spalls form on an individual ball on the bearing, friction is increased, and consequently, temperature is increased rapidly. Thus, at each speed, the bearing should have a particular "healthy" temperature. Consequently a wireless sensor that could be integrated directly on the bearing and monitor its real-time temperature is greatly needed in such health monitoring applications. This work focuses on the design, fabrication, packaging, and integration of a high-temperature wireless MEMS sensor that is placed directly on the bearing cage and transmits its temperature. The sensor is made up of micro-scale bimorphs, which are cantilever beams that consist of two different materials joined together. As temperature increases, the films expand at different rates, resulting in deflection of the beam. This deflection is sensed electronically, and the result is read wirelessly. This results in a first-of-its kind harsh-environment sensor. Particular attention is paid on the sensor's hermetic packaging and its associated RF performance, as well as the reliability (both cycling and creep) of the sensor itself.
Degree
Ph.D.
Advisors
Peroulis, Purdue University.
Subject Area
Electrical engineering
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