Robustness analysis quantifies and evaluates the variation of the model responses due to scattering input variables. Defining the inputs as random variables with distribution type, mean value and variation and further the dependence between the inputs by linear correlations, random sampling methods as Monte Carlo Simulation or Latin Hypercube Sampling (LHS) and Advanced Latin Hypercube Sampling (ALHS) are used to estimate the variation of the model responses.
By using LHS, the marginal distributions and the prescribed input correlations can be represented with a small number of samples. Based on the evaluated samples, the statistical properties of each response and safety margins of defined limits in terms of sigma levels are estimated. Along with the pure assessment of the response robustness, the source of the response variation is determined. Using variance based sensitivity analysis with help of Coefficients of Correlation, Coefficients of Importance, and MOP based Coefficients of Prognosis, the contribution of each input variable variation is quantified. Additionally, unexplainable response variation which may indicate implausible solver behavior can be detected and quantified by the MOP/CoP approach. In all statistical evaluations, failed designs are neglected.
Further information about methods of robustness analysis used in optiSLang can be found here.
Relevant Parameters
Only parameter with stochastic properties (stochastic or mixed parameter) are relevant for the robustness analysis.
Initialization Options
To access the options shown in the following table, double-click the Robustness system on the Scenery pane and switch to the Dynamic sampling tab.
| Option | Description | ||
|---|---|---|---|
| Dynamic sampling | This check box is selected by default. When cleared, only start designs are evaluated and considered for the robustness analysis. | ||
| Sampling type |
Select one of the following sampling methods: | ||
| Number of samples | Displays the number of samples used by the selected sampling type. | ||
Additional Options
To access the options shown in the following table, in any tab, click .
| Option | Description |
|---|---|
| Limit maximum in parallel |
Controls the resource usage of nodes in the system. When the check box is cleared (default), a value is chosen to ensure the best possible utilization of the child nodes. When the check box is selected, set the value manually to specify how many designs are sent to child nodes, limiting the maximum degree of parallelism for all children. Ansys recommends keeping the check box clear. |
| Auto-save behavior |
Select one of the following options:
The project, including the database, is auto-saved (depending on defined interval) after calculating this node/system (either when the calculation succeeds or fails). By default, all parametric and algorithm systems have selected, all other nodes have selected. |