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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum ( )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

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Posted by: Klaus Denkmayr ( )
Organization:ZF STEYR
Date posted: Thu Nov 9 5:59:26 US/Eastern 2000
Subject: pressure - lifetime relationship
A variable displacement pump is one of the key subsystems of our new automatic transmission. We have to define an accelerated test procedure to estimate the lifetime of the pump. Where can I find a relation between pressure and lifetime for a pump? Thanks in advance, Klaus


Subject: Pump Lifetime
Reply Posted by: Bruce Dudley ( )
Organization: Reliability analysis Center
Date Posted: Wed Nov 15 9:13:51 US/Eastern 2000
The Handbook of Reliability Prediction Procedures for Mechanical Equipment (NSWC-94/L07) has reliability models for pumps. This hanbook was produced by the Naval Sufrace Warfare Center, Cardrock Division, Bethesda MD. In this handbook, the basic failure modes that are discussed and modeled are: Cavitation, Interference, Corrosion, Material Fatigue and Bearing Wear. Pressure limits are described for rotary. reciprocating and centrifugal pumps in terms of pressure vs. gallons per minute. The information does not describe a direct relationship of pressure and life, but inferences from the material fatigue model and other models could be analyzed and substituted to determine the impact and combined with the accumulated damage theory could predict the fatigue damage due to overpressure testing. Coffin-Manson nonlinear power laws could be used to deternine the mechanical fatigue damage. Testing would have to be performed to determine the validity of any models developed.

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