[CCoE Notice] MS Thesis Presentation

[Abercrombie, Irene F]

MS Thesis Defense

Degradation-Based Reliability Estimate For Marine Electric Motor Pump Equipment

Robert M. Conachey

Date: Tuesday, November 20th, 2012

Location: Industrial Engineering Conference Room
Time: 3:30 pm

Committee Chair:
Dr. Qianmei Feng

Committee Members:
Dr. Ali K. Kamrani
Dr. Gangbing Song

Although individual ship operators have collected much condition monitoring data over the past 25 years, the analysis of these vibration data for failure time prediction and maintenance management is sparse.  There is a critical need within the marine industry and American Bureau of Shipping (ABS) for prediction of the failure time and accordingly, the remaining life of marine equipment based on degradation measures taken by condition monitoring techniques.

This thesis explores the degradation-based failure time estimation for electric motor pump units by using vibration analysis data provided from ships.  The work is unique in that the degradation/vibration data is taken under non-homogeneous environmental conditions, the vibration measuring equipment varies, the onboard units' characteristics vary by manufacturer and the sample population is very small: between 5 to as many as 15 units.

The degradation/vibration data is modeled as stochastic functions until a predetermined limit is exceeded which is considered failure.  Two approaches are applied.  In the first approach, the times to failure for individual degradation paths are modeled by a probability distribution.  In the second two-stage approach, the degradation path model is estimated by combining the estimates of model parameters for individual paths, and the failure time distribution is derived based on the stochastic degradation path model. Both methods are applied to analyze electric motor-pump units.
With this information, ship operators can readily assess remaining life of electric motor-pump combinations and make informed decisions concerning equipment shutdown and repair.  The  marine classification society can use the remaining life results and the inspection based maintenance model to improve the requirements in the PMP Guide.  For example, determine if the testing intervals presently in the PMP Guide should remain the same or modified to a shorter interval.  The marine classification society can use these results to advise its customers in the application towards ship maintenance procedures and thereby improve machinery and thus vessel reliability.


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