Post on 03-Apr-2018
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 1/46
SuperSMITH Software
WinSMITH Weibull Student Version
Step-by-Step Tutorial using
Case Studies
By Dr. Robert B. Abernethy
Copyrighted 2006
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 2/46
Problem#1:Plotting a Weibull with suspensions
Produce a Weibull plot based on the following data:
Note the differences between the two plots.
1. Use Median Ranked Regression (MRR),2. then Maximum Likelihood Estimates (MLE).
Failure Time
(cycles) Status
1500 Failure
1750 Suspension
2250 Failure
4000 Failure
4300 Failure
5000 Suspension
7000 Failure
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 3/46
Step by Step
• Open WinSMITH Weibull Student
Version (WSWS): double click the icon
on the desktop or go to “Start-->Programs-->Supersmith Weibull
• Input the data, using a negative sign for
suspensions. Or you can cut and pastefrom EXCEL.
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 4/46
Inputting data to SuperSMITH
Then click on the “paste”
bottle graphic.
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 5/46
Notice that the suspensions that were put in as a negativenumbers show up as a >1750 and >5000
After a few seconds, SuperSMITH automatically
produces your Weibull plot
Now, click on “Labels”
to put your titles on the plot
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 6/46
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 7/46
In order to save this plot to a PowerPoint slide click on the
“printer” graphic.
Getting your plot into PowerPoint
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 8/46
Now click on the “clipboard” graphic;
Then go to a blank page in Powerpoint and “paste.”
Getting your plot into Powerpoint(continued)
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 9/46
Final Median Ranked Regression Weibull
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 10/46
To do an Maximum Likelihood (MLE) Weibull
Click on this symbol
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 11/46
To do an MLE Weibull(continued)
Click on this symbol
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 12/46
To do an MLE Weibull(continued)
This is an MLE Weibull, and note the poor fit
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 13/46
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 14/46
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 15/46
To do a t0 correction in WSWS
Click on t0 – 3 parameter Weibull button
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 16/46
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 17/46
.
Note the
improvementin r2.. from 0.764
before to 0.98 now
To do a t0 correction in WSWS (continued)
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 18/46
Problem #3
• The following data represents the shear strength of brass and steel brake rivets.
• Do a Weibull of each… is there a significant difference between the two?
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 19/46
First, the brass rivet Weibull
Cut and paste the data from EXCEL™,
or punch in directly, then … Click here to put confidence bounds on the plot
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 20/46
Put confidence bounds on this Weibull
Click on this button for 2-sided
Confidence bounds……………...
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 21/46
Continuing to put Confidence bounds on a Weibull line
Accept 90% confidence…….
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 22/46
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 23/46
To see the “Report” Click on the right Tab
How to bring up the “Report”
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 24/46
The Report Shows Exact Readings From The Plot
Here are the exact 90% Confidence B10 Bounds which are also
90% Reliability Bounds. Other B lives may be added using the
report icon. Also shown are confidence bounds for eta and beta.
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 25/46
Now repeat this procedure for the steel rivets
90% confidence bounds at 10% reliability are (152.9-513.1)
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 26/46
Declare a Significant Difference
•Confidence bounds for Brass rivets at 90% reliabilityare (8.7-104.7).
•Confidence bounds for steel rivets at 90% reliability
are (152.9-513.1).
Conclusion: Since these bounds do not overlap at the B10 level,
there is a significant difference in the strength of the brass and steel
rivets with 90% confidence.
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 27/46
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 28/46
b seems high, try Lognormal and
Normal.
Doing a Ranked Regression Weibull as before
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 29/46
Now try a Lognormal
Click on this button
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 30/46
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 31/46
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 32/46
Now let’s try a Normal
Click on this button
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 33/46
Click on this button
Now let’s try a Normal (continued)
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 34/46
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 35/46
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 36/46
Doing a t correction
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 37/46
Doing a t0 correction
Click on this button
Doing a t correction (continued)
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 38/46
Doing a t0 correction (continued)
Click on this button, and the
“No” will change to “Yes”,then click the Green check
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 39/46
Doing a t0:
The fit is better,
R 2=.995,
so, 3-parameter Weibull
is your best choice????
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 40/46
To Find the Best Distribution
r2 is a good measure of fit but (r2 – CCC2) is more accurate
as explained in Chapter 3. Remember the “Report” we used
in Problem 3? It contains (r2 – CCC2) and this allows us to
do an accurate distribution analysis. If we click on the tab
above the plot for each distribution, the results are:Weibull 2-parameter (r2 – CCC2) = 0.1487
Weibull 3-parameter = 0.0739
Log Normal = 0.1511
Therefore from a statistical view the Log Normal best fitsour data set. However, the physics of failure and prior
experience may provide more information, at least equally
important, as discussed in Chapter 3.
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 41/46
Remember the Pump Problem in Chapter 4?
-1000
-1000
2000
-2000
-2000
-2000
-2000
3000
-3000
-3000
-3000
-3000
-4000
-4000
-4000
-4000
-4000
Let’s see if we cando the Abernethy
Risk failure forecast
to predict the
number of failureson the 18 remaining
pumps in the next
year. To make the
Weibull plot, Figure
4.1, enter the data
shown in Table 4-1
and repeated here.
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 42/46
Here is the plot. R squared is 1.0 because we only have two
failures. The expected usage for 1 year is 1000 hours for each
pump or 83.3 hours per month. Select the Abernethy Risk icon.
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 43/46
To make a failure forecast click on the Abernethy
Risk Icon which is here.
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 44/46
Enter Usage = 83.3 hours per month and click on
the Green Check
Wh t d thi t ll ? E t 2 3 f il i th t
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 45/46
What does this tell us? Expect 2.3 failures in the next year.
Expect the next failure in four months. The Now Risk is
2.5, close to the observed number 2, so a batch problem is
not indicated. In five years expect 14 failures.
7/28/2019 Student Tutorial.ppt
http://slidepdf.com/reader/full/student-tutorialppt 46/46
Summary
• We have illustrated how to input data, failures and
suspensions, obtain MRR and MLE plots, add confidence
bounds, do a distribution analysis and a failure forecast.
• We hope we have helped introduce you to WeibullAnalysis and we would be pleased if you would send us
your questions and/or comments.
• Bob Abernethy …..weibull@att.net