Configuring the Technique and Execution Options

You use the General tab to select the analysis type, the technique, and set any tuning parameters associated with the technique. In addition, you can also set options that you want the component to take during execution.

  1. Double-click the Six Sigma component icon .

    The Six Sigma Component Editor appears.

  2. From the Six Sigma Component Editor, click the General tab.

  3. Select a Run Mode:

    Option Description
    Six Sigma Analysis Isight evaluates the quality level of a single design. A set of points are sampled around the mean value point—the current design point—based on the analysis type and technique that you select. These sample points are used in postprocessing to calculate the number of sigma levels, the probability of success (reliability), the probability of failure, and the number of defects per million for each response for which response limits are defined. The mean and standard deviation for each response area are also calculated.
    Six Sigma Optimization Isight performs a six sigma analysis at each new design point selected during a robust design optimization strategy. The focus of robust design optimization is to search for robust or flat regions of a design space to reduce the effects of variations in uncertain design parameters, while satisfying design requirements with a high degree of certainty (reliability or sigma level). In a Six Sigma/Robust Optimization formulation, deterministic constraints (e.g., stress < strength) are replaced with results from the six sigma analysis performed at the current design point: sigma level > minimum desired sigma level, probability of failure < maximum acceptable failure probability, etc. The optimization objective (e.g., minimize mass) is replaced with a robust design objective formulation: maximize nominal performance and minimize performance variation. For information about the optimization techniques, see Configuring the Optimization Techniques.

  4. In the Analysis list, click one of the following:

    Option Description
    Reliability Technique The focus in structural reliability analysis is to assess the probability of failure—the probability of violating a constraint—of a structural component or system, resulting from performance (output) variation caused by the variation of uncertain, random (input) variables.

    For more information, see Overview of Reliability Analysis Methods.
    Monte Carlo Sampling Monte Carlo simulation techniques are implemented by randomly simulating a population of designs, given the stochastic properties of one or more random variables. The focus is on characterizing the statistical nature (mean, standard deviation, variance, range, distribution type, etc.) of the performance responses (outputs).

    For more information, see Monte Carlo Simulation.
    Design of Experiments In a Design of Experiments analysis a design matrix is constructed that specifies the values for the design parameters (uncertain parameters in this context) for each sampled point or experiment. For more information, see DOE Component.

  5. In the Technique list, select the technique of your choice.

    The technique’s tuning parameters appear in the Technique Options area. Information about the technique appears in the Technique Description area on the right side of the editor.

  6. If desired, review the information in the Technique Description area.

    For additional information on the techniques, see About the Available Techniques.

  7. In the Technique Options area, set the tuning parameter values for your technique.

    For more information, see Configuring the Analysis Types.

  8. In the Execution Options area, set the following:

    Option Description
    Reliability Technique Execute Reliability points in parallel. Select this option if you want the gradient sample points defined by the reliability technique to execute in parallel.
    Monte Carlo Sampling
    • Execute Monte Carlo sample points in parallel. Select this option if you want the sample points defined by the Monte Carlo simulation to execute in parallel. The convergence check interval may limit the number of sample points that are executed in parallel to batches that are the size specified for this convergence check interval.
    • After execution, reset to mean value point and run. Select this option if after execution you want all Monte Carlo simulation points and random variables set to their mean values, and the Monte Carlo subflow to execute one additional time. In this case, the Monte Carlo parameters (inputs and outputs) will be left at the values calculated for this “mean value point.” If this option is not selected, after execution the Monte Carlo parameters are left at the values associated with the last (random) Monte Carlo simulation point. This option is selected by default.
    • Convergence Check Interval. This integer value specifies the frequency at which the convergence of the Monte Carlo response statistics (low order—mean and standard deviation) are checked. The default setting requires the convergence of response statistics to be checked after every 25 sample points. Decreasing this value may result in premature convergence. Because the sample points are random or in random order/combinations, sufficient sample points are needed to determine if the response statistics are estimated accurately.
    • Convergence Tolerance. This value is the Monte Carlo termination criterion, which specifies the fractional change in response mean and standard deviation that will allow the simulation to be terminated before reaching the specified number of simulations. For example, if you want the simulation process to stop if the change in the response statistics goes below 5%, enter a value of 0.05 in the corresponding text box. Convergence is checked after each set of simulations defined by the Convergence Check Interval (by default, after each set of 25 simulations). The default Convergence Tolerance is 0.001.
    Design of Experiments
    • Execute DOE design points in parallel. All the design points defined by the design matrix are submitted for execution simultaneously. You may want to clear this option if components within the DOE subflow have license limitations or other requirements that mandate only one execution at a time.
    • Action when design point fails. If a design run fails during execution of the DOE technique, you can choose to have Isight ignore the failed run, fail the entire execution, retry the failed run (a specific number of times), or replace the failed run by re-executing with a specified percentage modification of the failed run.

  9. Set any desired Advanced Options.

    Advanced options include options that you want Isight to take after execution and termination criteria. For more information, see Configuring the Advanced Options.

  10. Map an option to a parameter.

    For more information, see Mapping Options and Attributes to Parameters.

  11. Click to import all or part of the Six Sigma component configuration from a file or to export the entire configuration to a file.

    This option provides you with an easy mechanism for quickly configuring the component using information that comes from an external source without manually entering all the information in the component editor. For more information, see About Importing and Exporting Configuration Files.

  12. Click OK to save your changes and to close the Six Sigma Component Editor.