Turbine Blade (SFEM - Collocation PC)

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In the following, Turbine Blade structure will be analysed using P-C formulation, more specifically where the coefficients will be estimated using the collocation formulation. The advantage of this implementation is that any response quantity, which is calculated by the FE solver and output to the ASCII formatted result file can be selected.

Definition of the probabilistic model

The same probabilistic model, as defined previously will be used here.

Performing SFEM Analysis

In this tutorial, turbine blade model will be used within the Collocation - PC analysis. After defining the input, the connector is created by right-clicking on the connector icon in the tree view and selecting the "add connector" option. The connector to NASTRAN is defined as follows for this example. Please note that the connector type should be chosen as NASTRAN within the configuration of the connector.


TurbineBladeCollocation2.jpg


Also, another important step within the definition of the connector is the creation of the injector. The definition of the identifiers (please note the formatting) for this tutorial is shown in the screenshot below:



TurbineBladeCollocation3.jpg


One should note at this point that the Collocation PC analysis works slightly different than the rest of methods within SFEM. The most important difference is that Collocation PC gives the possibility to select any response quantity (similar to the simulation methods), while for the other SFEM implementations the statistics are calculated only for the displacement vector.


Based on the above remark, an extractor has to be defined properly for a successfull Collocation P-C analysis. Please note that the selected responses should be output to the results file at the end of each FE analysis. In this tutorial, the stress in X direction and the von Mises stress of an arbitrary element (with ID 158) are selected as responses:


Definition of the XXstress response within the Extractor editor:


TurbineBladeCollocation4.jpg


Definition of the von Mises response within the Extractor editor:


TurbineBladeCollocation5.jpg


Once the connector is defined properly, a physical model has to be created, where the above defined connector is assigned in the evaluator window. Please note that the remaining input/output quantities appear automatically:


TurbineBladeCollocation1.jpg


Now, it can be proceed to the SFEM wizard: Select the PC method with the Collocation option (Note that the componentwise and solverbased implementations are not valid for this method):


TurbineBladeCollocation6.jpg


After clicking the next button, you can setup the advanced settings of the Sparse Grid toolbox, which is used within the Collocation analysis (it is not recommended to change the settings, unless you are not confident with what you are doing):   


TurbineBladeCollocation7.jpg


In the final menu, the user is asked to set the High performance settings. First select the Oracle Grid Engine and wait until all the queues are retrieved from the system. Once this step is completed click on the Queue column in the Analysis selection menu and select the NASTRAN queue. Click on finish to start the analysis.


TurbineBladeCollocation8.jpg

Results of the SFEM analysis


The estimated statistics of the response obtained using various methods are summarized in the following table:

Summary of Statistics (using Collocation PC)

Response

XY stress of Element 158 Von Mises stress of Element 158

Mean Value

4112.0
34757.5

CoV

0.048
0.048