Post buckling with SOL 601,106 workflow

The following steps summarize the process to create and solve a Simcenter Nastran SOL 601,106 post buckling solution. You perform a post buckling analysis of the model by using an arc length method.

Step	Summary	Detailed help topic
1.	Build the finite element (FE) model	In Pre/Post, define the geometry, material properties, mesh, constraints, and contacts as you would for other structural solution types.	Create new FEM and Simulation files
2.	Create the Simcenter Nastran solution	Set the analysis type to Structural and the solution type to SOL 601,106 Advanced Nonlinear Statics.	Create or modify a solutionSimcenter Nastran Advanced Nonlinear Theory and Modeling Guide, 1.2 Overview of Advanced Nonlinear Solution
3.	Configure the solution	At the solution level, modify the default output request, create modeling objects, and choose the Load Displacement Control (LDC) method (arc length method).	Configure SOL 601,106**Simcenter Nastran Advanced Nonlinear Theory and Modeling Guide, 6.2.6 Load-Displacement-Control (LDC) method
4.	Define the load for the LDC method	The LDC method automatically scales an applied load at each step. The solution scales the entire load vector, so you do not need to apply a load to the LDCGRID. The load can be time independent.	Define a force or moment load using components
5.	Solve the model	The Solution Monitor contains information about the status of your solution, and the Simcenter Nastran .f06 output file contains the requested results from your analysis.To locate the Simcenter Nastran .f06 file, right-click the solution and select Browse.	Solve the modelSolution Monitor
6.	Post process the results	Use the Post-Processing Navigator and the Results tab to manage and view the results from all steps. Note: If the model contains contacts, set the deformed scale to 1.0. Otherwise the results may show penetration between objects.	Post-processingControl the display of deformation
7.	Generate the load-displacement curve and graph the results	Use the .f06 file and third-party applications to extract the load vector multiplier and corresponding displacements.	Generate the load-displacement curve and graph

Configure SOL 601,106

1. In the Solution dialog box, click the General page.

2. Select the Ignore Material Temperature Dependence check box.Note: The LDC method does not support thermal loading.

3. Click the Case Control page.

4. Next to the Output Requests list, click Create Modeling Object .

5. In the Structural Output Requests dialog box, for each of the following pages, from the Output Medium list, select PLOT:Contact Results (only if your model contains contacts)DisplacementSPC ForcesStress

6. In the Structural Output Requests dialog box, click OK.

7. On the Case Control page, next to Time Step Intervals (0), click Create Time Step Intervals .Note: Although time is not a variable in an LDC analysis, the time step interval limits the solution to the maximum number of steps that you specify.

8. In the Modeling Objects Manager dialog box, click Create.

9. In the Time Step dialog box, set the following, and then click OK:ParameterDescriptionNumber of Time StepsThe maximum number of steps you want this solution to process. Note: Increase number of time steps, if the solution does not converge.Time IncrementThe time increment between time steps. Note: To avoid inaccurate or unstable results, a small time increment is recommended.Skip Factor for OutputThe interval at which the software saves results for output.

10. In the Modeling Objects Manager dialog box, click Close.

11. On the Case Control page, next to the Strategy Parameters list, click Create Modeling Object .

12. In the Strategy Parameters dialog box, do the following: Click the Analysis Control page, and from the Automatic Incrementation Scheme (AUTO) list, select LDC.Click the LDC Scheme page and set the following:ParameterDescriptionSpecify Grid Point for Prescribed Displacement****Grid Point IDThe ID of the grid to which the displacement will be applied.Degree of FreedomThe appropriate translation or rotation.Magnitude of Prescribed DisplacementThe maximum distance you want to allow for displacement.Critical Point Reached****Solution ContinuesIf you are using RBAR or RBE2, click the Translation page, and from the RBAR Elements Option or RBE2 Elements list, select Rigid.In the Strategy Parameters dialog box, click OK.

13. In the Solution dialog box, click the Parameters page, and select the Large Displacements check box.

14. Click OK.

Generate the load-displacement curve and graph

1. From the Simcenter Nastran .f06 file, extract the LOAD VECTOR MULTIPLIER (LVM) and CORRESPONDING DISPLACEMENT data  that is printed at the end of each converged step. Example: L O A D   V E C T O R   M U L T I P L I E R . . . .=   7.358336E-03 C O R R E S P O N D I N G   D I S P L A C E M E N T=  -1.000000E-02You can use a utility such as grep that performs repetitive searching tasks and prints the results.

2. Copy and paste the LVM and displacement data into a spreadsheet application with graphing capability, such as Microsoft Excel.

3. Multiply the LVM values by the applied load to compute the scaled load.Note: If the displacement values are negative, multiply them by –1.0, so the displacements increase from left to right on the X-axis of the graph.

4. In the spreadsheet application, create an Applied Load versus Displacement Magnitude graph from the load and displacement values you calculated in step 3.

Learn more

Nastran nonlinear analysis in Pre/Post

Controlling the iteration strategy in Nastran nonlinear analyses

Defining time step intervals for transient or nonlinear analyses

Controlling the birth and death times of elements in advanced nonlinear analyses

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Post buckling with SOL 601,106 workflow, Simcenter 3D 2021.1 Series

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