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Full-Text Articles in Engineering
A Reliable Mems Switch Using Electrostatic Levitation, Mark Pallay, Shahrzad Towfighian
A Reliable Mems Switch Using Electrostatic Levitation, Mark Pallay, Shahrzad Towfighian
Mechanical Engineering Faculty Scholarship
In this study an electrostatic MEMS beam is experimentally released from pull-in using electrostatic levitation. A MEMS cantilever with a parallel plate electrode configuration is pulled-in by applying a voltage above the pull-in threshold. Two more electrodes are fixed to the substrate on both sides of the beam to create electrostatic levitation. Large voltage pulses upwards of 100 V are applied to the side electrodes to release the pulled-in beam. A high voltage is needed to overcome the stronger parallel plate electrostatic force and stiction forces, which hold the beam in its pulled-in position. A relationship between bias voltage and …
Vibration-Based Defect Detection For Freight Railcar Tapered-Roller Bearings, Joseph Montalvo, Constantine Tarawneh, Arturo A. Fuentes
Vibration-Based Defect Detection For Freight Railcar Tapered-Roller Bearings, Joseph Montalvo, Constantine Tarawneh, Arturo A. Fuentes
Mechanical Engineering Faculty Publications and Presentations
The railroad industry currently utilizes two wayside detection systems to monitor the health of freight railcar bearings in service: The Trackside Acoustic Detection System (TADS™) and the wayside Hot-Box Detector (HBD). TADS™ uses wayside microphones to detect and alert the conductor of high risk defects. Many defective bearings may never be detected by TADS™ due to the fact that a high risk defect is considered a spall which spans more than 90% of a bearing’s raceway, and there are less than 20 systems in operation throughout the United States and Canada. Much like the TADS™, the HBD is a device …
Defect Prognostics Models For Spall Growth In Railroad Bearing Rolling Elements, Nancy De Los Santos, Constantine Tarawneh, Robert E. Jones, Arturo A. Fuentes
Defect Prognostics Models For Spall Growth In Railroad Bearing Rolling Elements, Nancy De Los Santos, Constantine Tarawneh, Robert E. Jones, Arturo A. Fuentes
Mechanical Engineering Faculty Publications and Presentations
Prevention of railroad bearing failures, which may lead to catastrophic derailments, is a central safety concern. Early detection of railway component defects, specifically bearing spalls, will improve overall system reliability by allowing proactive maintenance cycles rather than costly reactive replacement of failing components. A bearing health monitoring system will provide timely detection of flaws. However, absent a well verified model for defect propagation, detection can only be used to trigger an immediate component replacement. The development of such a model requires that the spall growth process be mapped out by accumulating associated signals generated by various size spalls. The addition …