Degradation Analysis Folio

Degradation analysis is a technique that uses the performance (degradation) measurements of a product over time to predict the point at which each unit in the sample is expected to fail. This analysis is useful for tests performed on products with very high reliability, where it is not possible to test the units to failure under normal conditions.

Weibull++ offers two types of degradation analysis folios:

The ReliaWiki resources portal has more information on degradation analysis at: http://www.reliawiki.org/index.php/Degradation_Data_Analysis.

What's Changed? Starting in Version 2019, you can now use the Inspection View with nondestructive folio data sheets.

Degradation Analysis Folio Setup

To add a degradation analysis folio, choose Home > Insert > Degradation, or right-click the Degradation folder in the current project explorer and choose Add Degradation on the shortcut menu.

In the setup window, select the type of degradation analysis folio to create. If you have Accelerated Life Testing activated on your computer, all four options will be available. The Accelerated Life Testing degradation analysis folios are similar to life data except that accelerated stress levels are used during testing to further reduce the test time required to obtain the predicted failure times.

Weibull++

  Nondestructive Degradation

  Destructive Degradation

Accelerated Life Testing

  Accelerated Nondestructive Degradation

  Accelerated Destructive Degradation

Degradation Folio Data Sheet

There are two options for displaying data in degradation analysis folio data sheets:

For nondestructive degradation analysis folios, there are two options for the data sheet view: the Unit View (which corresponds to the view used in all older versions of the software) and the Inspection View (new in Version 2019). When you create the folio, you will be able to choose which view to use.

For destructive degradation analysis folios, only the Unit View is available.

Unit View

When using this view, you enter measurements on a separate row for each unit and inspection time:

The following example shows a Weibull++ nondestructive degradation analysis for two automobile tires, A and B. The inspection time is in mileage because of its direct relation to the wear on the tires.

 

The following example shows an accelerated nondestructive degradation analysis for two LED units, A1 and A2. The light intensity is inspected every 50 hours and measured in milliamperes.

Inspection View

When using this view, you enter measurements for multiple units at each inspection time.

The following example shows a Weibull++ nondestructive degradation analysis for two automobile tires.

The following example shows a nondestructive degradation analysis for four LED units.

You can add additional unit IDs to the data sheet by clicking the Add/Remove Columns icon on the Main page of the control panel.

To switch between the views, choose Degradation > Format and View > [Switch to Unit View/Switch to Inspection View].

Conditions

If you are switching from the Inspection View to the Unit View:

Control Panel Settings

The degradation folio control panel contains most of the tools you need to perform a degradation analysis. For more information about control panels in general, see Control Panels.

Tip: If you are not certain which degradation model would provide the best fit for your data, you can use the Degradation Model Wizard to guide you through the selection process.

Nondestructive Degradation

Note: If the distribution and parameters are associated with a published model, then the model's name will appear as a link at the bottom of the Life Data Results area. Click the link to view the model's properties. See Publishing Models.

Destructive Degradation

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 analyzes the data set. This command is also available by choosing Degradation > Analysis > Calculate.

  Plot creates a new sheet in the folio that provides a choice of applicable plot types. This tool is also available by choosing Degradation > Analysis > Plot.

  QCP opens the Quick Calculation Pad, which allows you to calculate life data/life-stress data analysis metrics, identical to the calculations you can perform in a life data/life-stress data folio. This tool is also available by choosing Degradation > Analysis > QCP.

  Degradation Model Wizard opens the Degradation Model Wizard, which helps you select the degradation model that best fits your data. This tool is also available by choosing Degradation > Analysis > Model Wizard.

  Distribution Wizard opens the Distribution Wizard, which helps you select the distribution that best fits the data set. This tool is also available by choosing Degradation > Analysis > Distribution Wizard.

  Add/Remove Columns

    • For life data nondestructive folio data sheets, this allows you to add or remove subset ID columns when using the Inspection View.

    • For Accelerated Life Testing nondestructive data sheets, this allows you to add or remove columns for stress levels and, when using the Inspection View, add or remove subset ID columns.

This tool is also available by choosing Degradation > Format and View > Add/Remove Columns.

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

Related Topics and Links