Buckling Frequencies for Beams in Hypermesh
Download as PPTX, PDF1 like519 views
This document provides steps to model a hypermesh frame in Hyperworks to analyze buckling frequencies. It describes defining beam cross sections, materials, properties, nodes, beams, constraints, loads, buckling load collectors, loadsteps, and performing an analysis to obtain the first two buckling frequencies. Key steps include creating a steel material, rectangular beam section, applying pinned constraints to nodes C and A, a 1N load on node B, and using buckling load collectors and loadsteps to output the buckling frequencies in Hyperview.
Buckling Frequencies for Beams in Hypermesh
- 1. B U C K L I N G F R E Q U E N C I E S F O R B E A M S I N H Y P E R M E S H C R E AT E D BY : A K S H AY M I S T R I
- 2. SCENARIO • Youngs Modulus, E = 200E+3 N/𝑚𝑚2 • Yield Strength, 𝑆 𝑦 = 250 N/𝑚𝑚2 • Apply a load P = 1 N for finding buckling frequencies for the frame. • Consider y axis to be parallel to the screen and horizontal, to imagine the beam section orientation. • Thus, the side of the beams you see in the picture is of 100 mm and side 50 mm is perpendicular
- 3. DEFINING BEAM CROSS-SECTION • Open Hypermesh with OptiStruct as the user profile. • Go to 1D > HyperBeam > Standard Section and select the standard section type as solid rectangle. • Click on create. Enter values a = 100 and b = 50. • Then click on model view, first icon under word Model in top left corner.
- 4. DEFINE MATERIAL • Click on the material icon shown above and name it as steel. • Card Image : MAT1. • Click on create/edit. • Give value of E = 200E+3 = 2E+5. (N/sq. mm) • Click on return. • Please keep giving different color codes to different components seen in the specification tree.
- 5. DEFINING BEAM’S PROPERTY • Click on the property icon as shown above. • Select material and beam section we had created before. • Click on create.
- 6. CREATE A BEAM COMPONENT • We create this component to store beam elements. • Click on component icon as shown above. • Select the property which we had created before. • Click on create.
- 7. DEFINE NODES • Now we create nodes which represent pin-joints of our model. • Go to Geom > Nodes. • Create the following nodes: 1. 0,0,0 for point C. 2. 3000,4000,0 for point A. 3. 3000,-2000,0 for point B. Note that we are giving node distances in mm.
- 8. CREATING BEAMS BETWEEN NODES • Go to 1D > bars. Select property which we created and element type as CBEAM. • Give orientation using components (comes under first drop down arrow). • Give any one of the x or y component to be 1.00 so that the major axis of the beam is parallel to XY plane as shown. • Select first node at C and the one at top i.e A. • Click on 1D detailed representation to check the cross section of the beam is aligned correctly. • Similarly, select node A and Node B to create the vertical beam.
- 9. FINAL MODEL
- 10. CREATE LOAD COLLECTORS • Create a load collector named SPC with red color code, which will be used to constrain the nodes C and A. • Similarly, create a load collector for load application with green color code.
- 11. APPLYING CONSTRAINTS OR SPC’S • Go to Analysis > Constraints. • Nodes C and B are constrained, with pinned joints. In our case they are free to rotate about z-axis. • Hence, uncheck dof 6. • Also, before applying SPC’s check in the bottom right corner that SPC is the current load collector. If not, click on the bottom right corner and select SPC. • You can also make it current by right clicking on the SPC in specification tree and clicking on ‘Make it Current’. • Now click on nodes C and B to apply the SPC and click on create. • If you don’t see SPC’s on the nodes you can increase the relative size by giving value to 100 or more, as shown.
- 12. APPLYING LOAD • Go to analysis > forces. • Make Load as your current component. • Apply a load with 1 as magnitude parallel to x-axis. • You can increase the relative size, if the force vector is not visible.
- 13. CREATE BUCKLING LOAD COLLECTOR • Go to load collectors by clicking on • Create a load collector named Buckling which will store the buckling frequencies. • Give it a card image named as EIGRL which is actually eigen vector. • Click on create/edit. • Click on ND and give value equal to number of frequencies you want to see. (2 in our case) • Note that this value cannot exceed degrees of freedom of the model.
- 14. CREATING LOADSTEPS • Go to analysis > loadsteps. • Create a static loadstep named static. • Check SPC and Load and select load collectors for them by clicking on equal to sign. • Click on create. • Now change type from linear static to linear buckling and give name as buckling. • Select SPC we created for SPC and static (the loadstep we created in previous steps) for STATSUB(BUCKLING). • For METHOD(STRUCT) select the buckling load collector. • Click on create.
- 15. PERFORM ANALYSIS • Now we have completed our model and we can run it for analysis. • Go to Anlaysis > OptiStruct. • Select the run options as shown below. • Remember to save your file as with .fem extension in a separate folder, which will get result files after analysis gets completed. • You will get a pop-up window showing message Analysis completed. • Click on the results to open Hyperview player which will help to see final results.
- 16. POP-UP WINDOW
- 17. RESULTS IN HYPERVIEW • When Hyperview opens, click close for any message popping up. • Click on apply and click Yes for any other pop- ups. • Click on contour button and click on apply to see deformations.
- 18. BUCKLING FREQUENCIES • Deformations are, however not important here since we applied a unity load to get buckling frequencies. • To get buckling frequencies, change subcase 2 from linear to buckling. • Below the cases you can see two frequencies described as mode 1 and 2. • These are the buckling frequencies we wanted to get.