A compressor impeller was submitted for investigation of what was reported to be a corrosion failure. Laboratory analysis determined that the cause of metal wastage was not corrosion. Failure of the impeller was due to fatigue cracking caused by plate mode (edge) vibration between the vanes. Vibration testing determined that two specific frequencies excited the impeller in this manner. The source of these excitation frequencies was never determined. However, a new impeller with a modified geometry was designed so that it was “de-tuned”; i.e., the vibration nodes were moved away from the known excitation frequencies. The compressor with the modified impeller has been running for over four years with no further problems.

Subject
Scanning electron microscopy, Materials, Secondary cracks, Grinding, Inspection, Metal loss, Mechanical failure, Reagents, Vibration, Titanium, Fracture, Damage, Hydrogen
© 2001 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2001
Association for Materials Protection and Performance (AMPP)
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