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| ==CD GLL-Weibull Example== | | <div class="noprint"> |
| <br> | | {{Examples Box|ALTA Examples|<p>More application examples are available for the Cumulative Damage model:</p>{{Examples Both|http://www.reliasoft.com/alta/examples/rc8/index.htm|Multiple Time-Dependent Stresses Example|http://www.reliasoft.tv/alta/appexamples/alta_app_ex_8.html|Watch the video...}}{{Examples Both|http://www.reliasoft.com/alta/examples/rc4/index.htm|Step-Stress Test for Automotive Part|http://www.reliasoft.tv/alta/appexamples/alta_app_ex_4.html|Watch the video...}}{{Examples Both|http://www.reliasoft.com/alta/examples/rc1/index.htm|Voltage Step-Stress Example|http://www.reliasoft.tv/alta/appexamples/alta_app_ex_1.html|Watch the video...}}}} |
| A sample of 18 units of an electronic component was subjected to temperature and voltage stresses. The temperature was initially set 100K and was then continuously increased to 200K over a period of 20 hours. The temperature was again increased at 120 hours to 300K over a 20 hours period as shown in the next figure.
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| [[Image:ALTA12.3.gif|thumb|center|150px|Temperature profile.]]
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| The voltage was initially set 4V and was then increased continuously to 8V over a period of 10 hours. The voltage was again increased at 110 hours to 12V over a 10 hours period as shown in the next figure.
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| [[Image:ALTA12.4.gif|thumb|center|150px|Voltage profile.]]
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| The failure times, as entered in ALTA, are shown in the next figure.
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| [[Image:CD_GLL_Example_3.gif|thumb|center|150px|]]
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| The stresses are transformed using an Arrhenius life-stress relationship for temperature, a Power Law life-stress reliationship for voltage and the Weibull distribution as the underlying distribution.
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| [[Image:CD_GLL_Example_4.gif|thumb|center|150px|]]
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| The estimated model parameters are shown next.
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| ::<math>\begin{align}
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| \widehat{\beta }=\ & 3.507277 \\
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| \widehat{{{\alpha }_{0}}}=\ & -1.377671 \\
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| \widehat{{{\alpha }_{1}}}=\ & 450.488282 \\
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| \widehat{{{\alpha }_{2}}}=\ & 1.981082
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| \end{align}</math>
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| The use level (temperature = 100K, voltage = 4V) reliability plot is shown in the next figure.
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| <br>
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| [[Image:ALTA12.5.gif|thumb|center|150px|Reliability plot at normal use conditions (100K and 4V).]]
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