Track 1 Session 4

1:40 to 2:40 p.m. Wednesday, October 20, 2010

Data Analysis Made Easy

To determine the characteristics of a critical component, we conduct tests and collect data. The data is only useful when analyzed, and when the information used to predict system reliability. During system tests, the number of failures due to the component under study is recorded. When a system fails due to other causes, the failure is censored. All the failure events are subjected to a specific methodology and plotted. First, they are plotted in different graphs to determine the appropriate distribution. Data are read off the distribution chart to give the straight line fitting. The shape parameter, characteristic life and others are read from the chart. The shape parameter gives an indication as to whether the failure rate is decreasing, constant or increasing. The characteristic life indicates the time by which 63.2% of the specific critical component under study has failed. These data are used for reliability prediction.

Manual plotting is laborious. A helpful tool is ReliaSoft's Weibull++ software. This paper compares the manual step-by-step procedure with using Weibull++.

In using Weibull++, the click of the cursor shows which distribution gives the best fitting of a straight line. Several distributions will be named, in order from the best to the worst. With a click of the cursor a) we can view the reliability at specific life; b) at specific life, what the reliability of the specific component will be; c) given that the system is working now, what are the possibilities that it will work the next period of time and d) what warranty period to provide.

ReliaSoft's Weibull++ software is a useful tool in data analysis. It frees up one's time to do other value added work.

Key Words: Exponential Distribution, Normal Distribution, Lognormal Distribution, Weibull Distribution, Median Ranking, Reliability, Failures, Hazard Plotting, Probability Plotting, Singly Censored, Multiply-Censored, Shape-Parameter, Characteristic Life, Mean Life, Zero Minimum Life, Non-Zero Minimum Life, Straight Line, Percentile

Serene Tay Poh Choo

Advanced Material Engineering Pte Ltd