Related Topics:

ALTA Standard Folio Control Panel

ALTA Single-Stress Example

ALTA Two-Stress Example

ALTA Standard Folio Setup

The ALTA standard folio contains the tools for performing an accelerated life testing data analysis. A setup window for configuring your folio will be displayed when you:

The first page of the Data Sheet Setup window is shown next.

This page of the window is used to select what types of data can be included in the data sheet. The available options are described next. (See Data Types for more detailed descriptions of each data type below.)

In the example shown next, the first unit was operational at the start of the test but found failed at 150 hours (thus, it is a left censored data point). The second unit was still operating at 150 hours, but it failed at some point prior to the next observation at 300 hours, and so on.

The first row represents 2 left censored data points (2 units were observed at 24 hours and found to be failed). The fourth row contains an exact failure time (failure at 100 hours) for 1 unit. The sixth row represents an interval suspension for 5 units that were found operational at 120 hours and then also at 150 hours. The remaining rows represent interval data for units that failed during the test.

Note that when you select a data type, the preview table at the bottom of the setup window will show you the name of the data entry columns that will appear in the data sheet.

If you are creating a new folio, you will also need to specify the time units appropriate for your data. Units may be measured in time, distance, weight, etc. The appropriate columns in the data sheet will be automatically configured for the units you select. If you later wish to change the time units of an existing data sheet, click the Change Units icon on the Main page of the control panel of the data sheet.

Note: In Version 8, you now have the ability to define the time units used for the data set and calculations. For example, if your data set contains failure times in hours, you now have the option to perform calculations using different time units such as years, months, days, etc. The software performs the unit conversion automatically.

Authorized users can define the time units that will be available for use in any project within the database and set up the conversion factors.

If you wish to use the same stress column and stress level settings that were used when you last set up an ALTA standard folio—or if you are only changing the data type of an existing folio—click OK to close the window and view your folio. Otherwise, click Next> to display the second page of the window.

You can use this page to do the following:

IMPORTANT: Temperature values must always be entered in absolute units (e.g., Kelvin or Rankine). To convert temperature values in the data sheet that were entered in Celsius or Fahrenheit to absolute units, choose ALTA > Options > Convert Stress Values.

Like the first page of the setup window, there is a preview at the bottom of the page that shows you how the names of the associated columns will appear in the data sheet.

 

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