Modal Analysis using Optistruct

AIM:

To carry out modal analysis in the given bracket using optistruct solver.

PROCEDURE:

1. Open Hypermesh and select Optistruct as the solver.

2. Go to Import Solver Deck>>Import Geometry>>File type: IGES>>Import the necessary file.

3. Change the view to Topo Mode to check for the errors.

4. Now, go to 3D>>Tetramesh>>Volume Tetramesh>>Element size: 4mm>>Element Type: R-Trias>>Mesh. The meshed model is shown in the figure below.

5. Go to components tab and create a property as PSOLID as shown in the figure below. 

6. Create a new material to in the model. The material steel is selected for this simulation. 

7. Now create rigids as load collectors along the geometry as shown in the figure below. All the degrees of freedom are arrested.

8. Assign the property to the component.

9. Create another load collector to define the eigen values. The card name EIGRL is used for this analysis. In this there are two values namely V1 and V2 are used to define the range of modes. But here we are not defining it since the solver iterates using all possible frequencies. The number of modes is defined as 10. This is shown in the figure below.

10. Now, a load step card is created to give the output requests. The strain and strain energy outputs are requests in the deck as shown in the image below.

11. Save the file with a suitable name. Go to Analysis>>Optistruct>>Run the simulation.

RESULTS AND DISCUSSION:

1. The following output is obtained after the simulation.

2. The elemental strain energy for mode 1 is shown in the figure below.

Note:

1. Modal analysis does not give any results for deformation. For obtaining deformation, static strucutural analysis has to be carried out. 

2. Number of modes indicate the eigen vector. Ideally, there are infinite number of modes possible. But in general the software accounts for the mode which causes the largest deformation.

3. The elemental strain are evaluated for each mode and the corresponding values are noted down. For highly deforming region, suitable reinforcements are given to avoid failure due to vibration.

CONCLUSION:

Therefore, modal analysis is carried out in the given model using optistruct as the solver.

Drive Link: https://drive.google.com/file/d/1GDH-6-YLgCdadSQV5_cf63U3_F5okvfn/view?usp=sharing