Last year’s Prosig ISVR Student Prize as won by Paul Clark for his project titled “A Mobility Model to Predict the Isolator Effectiveness of an Automotive Compressor”. Paul graduated this summer and was presented with his prize at his graduation ceremony at University of Southampton.
In the abstract for his project, Paul describes it as…
This project concerns the study of vibration isolation of an automotive compressor. In particular the measure of isolator effectiveness is discussed, and how it evolves from the mobility approach. The mobility approach offers a technique for splitting a complex structure into sub-structures for easier analysis. Isolator effectiveness predictions can be made by obtaining the mobilities of each sub-structure, without having to measure or predict the performance of the whole combined system.
The automotive compressor used as a case study was provided by Jaguar Landrover. It is a component in a system for controlling the ride height the vehicle. The compressor system includes a compressor mounted to a plate using four viscoelastic mounts. It is the job of the mounts to prevent vibrations travelling from the compressor into the vehicle chassis.
To predict the isolator effectiveness of the system a number of assumptions were required, which allowed the compressor to be modelled as single degree of freedom system. Various measurements were made to prove these assumptions, and it was found valid to model the compressor in only one degree of freedom.
Measurements and simple models of the mobility of the compressor, pan and mounts were made. Testing on the compressor and pan involved the use of an impact hammer. Testing of the mounts required a shaker rig, and a technique of measuring complex modulus properties which could be included in a damping model.
The three mobility measurements were incorporated into an isolator effectiveness prediction. An alternative method of directly measuring the isolator effectiveness was devised and implemented, to allow comparisons between the two isolator effectiveness measurements. A good correlation between the two was discovered.
The isolator effectiveness of the automotive compressor was found to increase with frequency. At low frequencies the addition of an isolator in the system appears to have a detrimental effect, but with increasing frequency the isolator causes very good isolation between the compressor and pan.
James Wren and Adrian Lincoln from Prosig, who assessed the projects were particularly impressed with Paul’s project because he demonstrated a deep understanding of the underlying principles involved. Further, his project proposed a clear and concise route to reduce the transmitted vibration, something the project partner Jaguar Land Rover, would be very pleased with. Paul demonstrated an intellect and ability of an engineer with some years experience, not that of an undergraduate.
Prosig would like to congratulate Paul on his graduation and winning the prize and wish him all the best his future career.
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