Related Topics:
	Application Setup

Application Setup ALTA Folios Page

The ALTA Folios page of Weibull/ALTA's Application Setup allows you to set the options that apply only to ALTA folios. Options that apply to both Weibull++ and ALTA appear on other pages.

• Data Sheet Options for ALTA

• • To display the likelihood function value in the control panel Analysis Summary area, select the Show likelihood value (LK) option.

  • To display the activation energy (Ea) in the control panel Analysis Summary area, select the Show activation energy option. Note that this option does not apply to the inverse power law, proportional hazards or general log-linear life-stress models.

  • • In the Units drop-down list choose either Kelvin or Rankine for the time units in which to display the activation energy.

  • To display the selected stress columns in the data sheet with a colored border, select the Indicate stress columns used option, then click the Color box to open the palette and select a border color.

• Default Grouped Data Settings

• • If you select Ungroup points on plot, ALTA assigns an individual median rank value to each data point (observation) within a group. When plotted, the points in each group will appear vertically aligned. If not selected, the observations in each group will be represented by a single point at the highest median rank value within the group. The line is independent of whether data points are treated as grouped or ungrouped.

• Other Options

• • To open other ALTA standard folios while the Use Stress Level window remains open, select the While the Use Stress window is open, have access to all folios option. The Use Stress Level window will be linked to the currently active data sheet. If not selected, you must close the Use Stress Level window in order to return to the folios.

• In the Default Life Distribution area select whether the Weibull, Lognormal or Exponential distribution will be selected by default for ALTA standard folios. If lognormal is selected as the default and you select a model for which the lognormal distribution is not available (i.e., Proportional Hazards or Cumulative Damage in ALTA 9 PRO), the life distribution will automatically reset to Weibull.

• For time-dependent stress profiles, in the Calculations Options area select the option that specifies when ALTA will apply the stress to a time-to-failure data point that occurs at the both the End time of one segment and the Start time of another segment:

• • Select Implement stress at end of step to apply the stress from the later segment.

  • Select Implement stress at beginning of step to apply the stress from the earlier segment.

For example, suppose that the selected stress profile applies a stress of 300K to failure times between 0 and 100 hours and a stress of 350K to failure times between 100 and 200 hours. If the observed failure time is 100 hours, you must determine whether to apply the 300K or 350K stress to that data point. These settings are available only in ALTA PRO and apply only when Cumulative Damage is selected as the life-stress model.

• Select Allow large Beta values (Cumulative Damage model) to display beta values up to 250 when using the cumulative damage model. If not selected, the default maximum beta value is 100. This option is available only in ALTA PRO and applies only when Cumulative Damage is selected as the life-stress model.