Related Topics and Links:

ALTA Life-Stress Data Folio

Control Panels

ALTA Plots

ALTA Quick Calculation Pad


 ReliaWiki: Distributions Used in Accelerated Testing

ALTA Life-Stress Data Folio Control Panel

The ALTA life-stress data folio control panel allows you to configure the analysis settings for the data sheet and view/access the results. It consists of multiple pages, each containing options for performing particular tasks. This topic focuses on the Main page of the ALTA life-stress data folio control panel, which contains most of the tools you will need to perform accelerated life testing analysis. For more information about the control panel in general, see Control Panels.

Control Panel Main Page

The Main page of the ALTA life-stress data folio control panel includes the following settings:

Depending on your application settings, additional information may also be displayed:

Additional Results

The following tools may also be used in conjunction with your own engineering knowledge about the model in order to further evaluate the fit of the model to the data set.

Folio Tools

The folio tools are arranged on the left side of the Main page of the control panel. Use these tools to manage data and experiment with the results of your analysis.

  Calculate estimates the parameters of the chosen model, based on the current data set and the specified analysis settings. This tool is also available by choosing Life-Stress Data > Analysis > Calculate.

  Plot creates a new sheet in the folio that provides a choice of applicable plot types. For life-stress data folios, this includes plots such as Use Level Probability, Reliability vs. Time, Life vs. Stress, etc. You can also create a Plot sheet by choosing Life-Stress Data > Analysis > Plot.

  QCP opens the ALTA Quick Calculation Pad, which allows you to calculate results, such as the mean life and the probability of failure, based on the currently active data sheet. This tool is also available by choosing Life-Stress Data > Analysis > Quick Calculation Pad.

  Distribution Wizard opens the ALTA Distribution Wizard, which helps you select the life distribution that will best fit your data. This tool is also available by choosing Life-Stress Data > Analysis > Distribution Wizard.

  Alter Data Type opens the Data Sheet Setup window, which allows you to change the data entry columns in the current data sheet. Note that when you change the setup, you may lose information already entered in the data sheet. For example, switching the data sheet from one that supports interval data to one that supports only right censored data will remove all the inspection times. This tool is also available by choosing Life-Stress Data > Format and View > Alter Data Type.

  Add or Remove Columns allows you to add/remove columns for stress levels and unit IDs.

  Change Units opens the Change Units window, which allows you to change the units for the values in the current data sheet.

  Auto Group Data opens the Auto Group Data window, which allows you to group together identical data points. Grouping data significantly speeds up calculations when you have a very large data set. This tool is also available by choosing Life-Stress Data > Format and View > Auto Group Data.

  Alter Parameters (also called Alter Parameters w/o Recalculation) allows you to manually alter the value of one (or more) parameters, while keeping the original values of the rest of the parameters and the variance/covariance matrix the same. The LK value, the solution line on plots and all subsequent analyses will be based on the modified set of parameters.

  Likelihood Ratio Test opens the Likelihood Ratio Test tool, which allows you to assess the assumption of a common shape parameter across all the stress levels used in the test. This assumption underlies the use of any model that includes the Weibull or lognormal life distribution. You can also open this tool by choosing Life-Stress Data > Options > Likelihood Ratio Test.

  Transfer Data to Weibull++ allows you to transfer data from the ALTA life-stress data folio to a Weibull++ life data folio.

 

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