Logistic Model - Auto Transmission Example: Difference between revisions

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<noinclude>{{Banner RGA Examples}}
<noinclude>{{Banner RGA Examples}}
''This example appears in the [[Logistic|Reliability Growth and Repairable System Analysis Reference book]]''.
''This example appears in the [https://help.reliasoft.com/reference/reliability_growth_and_repairable_system_analysis Reliability growth reference]''.
</noinclude>
</noinclude>


The following table presents the reliabilities observed monthly for an automobile transmission that was tested for one year.
The following table presents the reliabilities observed monthly for an automobile transmission that was tested for one year.


:1) Find a Logistic reliability growth curve that best represents the data.
#Find a Logistic reliability growth curve that best represents the data.
:2) Plot it comparatively with the raw data.
#Plot it comparatively with the raw data.
:3) If design changes continue to be incorporated and the testing continues, when will the reliability goal of 99% be achieved?
#If design changes continue to be incorporated and the testing continues, when will the reliability goal of 99% be achieved?
:4) If design changes continue to be incorporated and the testing continues, what will be the attainable reliability at the end of January the following year?
#If design changes continue to be incorporated and the testing continues, what will be the attainable reliability at the end of January the following year?


{|border="1" align="center" style="border-collapse: collapse;" cellpadding="5" cellspacing="5"
{|border="1" align="center" style="border-collapse: collapse;" cellpadding="5" cellspacing="5"
|+'''Reliability data'''
|+'''Reliability Data'''
!Month
!Month
!Observed Reliability(%)
!Observed Reliability(%)
Line 41: Line 41:


'''Solution '''
'''Solution '''
<ol>
<li>The next figure shows the entered data and the estimated parameters.
<br>
<br>
:1) The next figure shows the estimated parameters.
[[Image:rga8.7.png|center|600px]]
<br>
<br>
[[Image:rga8.7.png|thumb|center|400px|Entered data and the estimated Logistic parameters.]]
</li>
<li>The next figure displays the Reliability vs. Time plot.
<br>
<br>
:2) The next figure displays the Reliability vs. Time plot.
[[Image:rga8.8.png|center|450px]]
<br>
<br>
[[Image:rga8.8.png|thumb|center|400px|Reliability vs. Time plot.]]
</li>
<li>Using the QCP, the next figure displays, in months, when the reliability goal of 99% will be achieved.
<br>
<br>
:3) Using the QCP, the next figure displays when the reliability goal of 99% will be achieved.
[[Image:rga8.9.png|center|450px]]
<br>
<br>
[[Image:rga8.9.png|thumb|center|400px|When the reliability goal of 99% will be achieved.]]
</li>
<li>The last figure shows the reliability at the end of January the following year (i.e., after 20 months of testing and development).
<br>
<br>
:4) The last figure shows the reliability at the end of January the following year (i.e., after 20 months of testing and development).
[[Image:rga8.10.png|center|450px]]
<br>
[[Image:rga8.10.png|thumb|center|400px|The reliability at the end of the following January (month=20)]]
<br>
<br>
</li>
</ol>

Latest revision as of 21:21, 18 September 2023

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This example appears in the Reliability growth reference.


The following table presents the reliabilities observed monthly for an automobile transmission that was tested for one year.

  1. Find a Logistic reliability growth curve that best represents the data.
  2. Plot it comparatively with the raw data.
  3. If design changes continue to be incorporated and the testing continues, when will the reliability goal of 99% be achieved?
  4. If design changes continue to be incorporated and the testing continues, what will be the attainable reliability at the end of January the following year?
Reliability Data
Month Observed Reliability(%)
June 22
July 26
August 30
September 34
October 45
November 58
December 68
January 79
February 85
March 89
April 92
May 95

Solution

  1. The next figure shows the entered data and the estimated parameters.
    Rga8.7.png


  2. The next figure displays the Reliability vs. Time plot.
    Rga8.8.png


  3. Using the QCP, the next figure displays, in months, when the reliability goal of 99% will be achieved.
    Rga8.9.png


  4. The last figure shows the reliability at the end of January the following year (i.e., after 20 months of testing and development).
    Rga8.10.png