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With the Synthesis API, you can leverage the ALTA analysis engine to perform accelerated life testing data analysis on an external data source. In this tutorial, you will learn how to use the API to create and analyze a data set, and then estimate the probability of failure.

Tutorial: Accelerated Life Testing Data Analysis - Single Stress

The following example demonstrates how to define an ALTA data set and obtain analysis results from a single stress model. A discussion of the example follows.

The following table shows the data set for this example.

Number in State	State	Time to F or S	Temperature
1	F	245	353
5	S	250	353
1	F	110	373
1	F	180	373
1	F	200	373
3	S	250	373
1	F	50	393
1	F	70	393
1	F	88	393
1	F	112	393
1	F	140	393
1	F	160	393

VB.NET

Imports SynthesisAPI 

Module Module1
   Sub Main()

  'Declare a new ALTADataSet object.  
   Dim ADS As New ALTADataSet

  'Define a stress type with use stress level = 300.  
   ADS.AddStressDefinition("Stress1",,300)

  'Add failure times to the data set. 
   ADS.AddFailure(245, 1, 353)
   ADS.AddFailure(110, 1, 373)
   ADS.AddFailure(180, 1, 373)  
   ADS.AddFailure(200, 1, 373)
   ADS.AddFailure(50, 1, 393)
   ADS.AddFailure(70, 1, 393)
   ADS.AddFailure(88, 1, 393)
   ADS.AddFailure(112, 1, 393)
   ADS.AddFailure(140, 1, 393)
   ADS.AddFailure(160, 1, 393)
   
  'Add suspensions to the data set. 
   ADS.AddSuspension(250, 5, 353)   
   ADS.AddSuspension(250, 3, 373) 
 
  'Use the Arrhenius-Weibull model to analyze the data set. 
  'Keep all other analysis settings at default. 
   ADS.AnalysisSettings.ModelType = ALTASolverModel.Arrhenius
   ADS.AnalysisSettings.Distribution = ALTASolverDistribution.Weibull
 
  'Analyze the data set. 
   ADS.Calculate()

  'Calculate the B10 life and display the result. 
   Dim r As Double
   r = ADS.FittedModel.Time(.90)
   MsgBox("B10 Life: " & r)

   End Sub
End Module

Discussion

The ALTADataSet class represents an ALTA standard folio data sheet. The class contains all the methods and properties that allow you to define a data set and fit a life-stress relationship and distribution to the data.

 'Declare a new ALTADataSet object.  
  Dim ADS As New ALTADataSet

The data set can contain failures, suspensions or interval data. The following example shows how to use the AddFailure method to define failures and the AddSuspension method to define suspensions.

 'Add failure times to the data set. 
  ADS.AddFailure(245, 1, 353)
  ADS.AddFailure(110, 1, 373)
  ADS.AddFailure(180, 1, 373)  
  ADS.AddFailure(200, 1, 373)
  ADS.AddFailure(50, 1, 393)
  ADS.AddFailure(70, 1, 393)
  ADS.AddFailure(88, 1, 393)
  ADS.AddFailure(112, 1, 393)
  ADS.AddFailure(140, 1, 393)
  ADS.AddFailure(160, 1, 393)
   
 'Add suspensions to the data set. 
  ADS.AddSuspension(250, 5, 353)   
  ADS.AddSuspension(250, 3, 373) 

The AnalysisSetting property returns an ALTAAnalysisOptions object, which represents the analysis settings of the ALTADataSet object. In the following example, we use the ModelType and Distribution properties of the ALTAAnalysisOptions class to specify the life-stress relationship and distribution.

 'Use the Arrhenius-Weibull model to analyze the data set. 
 'Keep all other analysis settings at default. 
  ADS.AnalysisSettings.ModelType = ALTASolverModel.Arrhenius
  ADS.AnalysisSettings.Distribution = ALTASolverDistribution.Weibull

To analyze the data set, use the Calculate method. The method returns a message box that shows the estimated parameters of the model, based on the settings specified in the AnalysisSettings property.

 'Analyze the data set. 
  ADS.Calculate()

The FittedModel property gets a cModel object that represents the fitted model of the accelerated life testing data analysis. From the model, you can calculate useful metrics such as reliability, failure rate, mean time, etc. In this example, we calculate for the B10 life.

  'Calculate the B10 life and display the result. 
   Dim r As Double
   r = ADS.FittedModel.Time(.90)
   MsgBox("B10 Life: " & r)

Notes

For a two-stressTo analyze results for a

References

• ALTADataSet Class
• ALTADataSet.AddFailure Method
• ALTADataSet.AddSuspension Method
• ALTADataSet.Calculate Method
• ALTAAnalysisOptions Class
• cModel Class