Reliability Model for Compressor Failure

SMRE Term Project

Paul Zamjohn

August 2008

ProposalCompressor Failure Data: Case 2.16 of Blischke-DATA

Data on “large air compressors” for a military base near the seacoast will be analyzed to determine the probabilistic failure structure. Air compressors require “bleeding” prior to operation to function properly, the data below represents failure due to binding in the bleed system. Salt air due to proximity to the ocean is believed to be a major contributor, nothing is known about other variables and their impact to reliability.

Analysis will include:

•Generating the descriptive statistics•Selecting the distribution that best describes the data and the distribution

parameters•Calculating the failure probability density function (f) •Calculate the cumulative distribution function (F)•Calculating the survival probability function (R)•Calculating the hazard function (z)•Determining the MTTF•Perform Monte Carlo simulation to model and assess reliability

Operating time for 202 compressors (failed and unfailed units)operating hours frequency

0-200 0201-300 2301-400 0401-500 0501-600 2601-700 2701-800 10801-900 26

901-1000 271001-1100 221101-1200 241201-1300 241301-1400 111401-1500 111501-1600 201601-1700 81701-1800 41801-1900 21901-2000 32001-2100 32101-2200 1

Compressor Failure Data

20001000500

99.9

90

50

10

1

0.1

Start

Perc

ent

20001000500

99.9

99

90

50

10

1

0.1

StartP

erc

ent

100001000100101

99.9

90

50

10

1

0.1

Start

Perc

ent

100001000

99.9

99

90

50

10

1

0.1

Start

Perc

ent

Weibull0.971

Lognormal0.952

Exponential*

Loglogistic0.954

Correlation Coefficient

Probability Plot for StartLSXY Estimates-Arbitrary Censoring

Weibull Lognormal

Exponential Loglogistic

Comparison of Monte Carlo vs.Equation

0.0000

0.2000

0.4000

0.6000

0.8000

1.0000

1.2000

250 500 750 1000 1250 1500 1750 2000

(hours)

MC

EQ

Failure vs. Reliability Function Probability Distribution Function

Hazard (failure) Rate Monte Carlo Simulation vs. Equation