Creation of 1D Elements - Bar Beam Rod

INTRODUCTION

BAR ROD & BEAM

Loading conditions plays a important role between bar rod and beam. A bar and a rod can be only subjected to axial loads like tension or compression, whereas beam can be subjected to any types of load like tension, compression, torsion, and bending.

MIDSURFACING

Midsurface is 2D element, extracted to represent the 3D surface. It can be done only on surface with uniform thickness. Whenever we mesh a 3D model, large nodes and elements will be involved, which in turn will consume huge time,memory and processing power to complete the task. To overcome this type of difficulty midsurface is used to represent the entire 3D model.

OBJECTIVE

The main objective of this project is to understand different options in 1D element and apply those to create rod, beam & bar element according to the given conditions and also to study the hyperbeam envrionment where we can define cross sections. Understanding material, property application and different node selecting techniques and to learn about rbe2 and rbe3 elements and their properties.

PROCEDURE

1) Import the model which are going to be travelled throughout this project. Use import model option as shown.

2) Go to Geom>Midsurface, and select the top bracket & hit extract button to create midsurface of top bracket.

3) Rename the Midsurface component to Bracket1.

4) Similarly do the same procedure for bottom bracket also to extract the middle surface.

5) Create a new folder under components and rename to Bracket2

6) Delete the solid bracket and also delete the folder Parallel_Bracket_body_0 & Parallel_Bracket_body_1 to avoid confusion during progress. Use delete option under graphical area.

7) Move the selected (White colour) surface to the Bracket2 folder. To acheive this, use TOOL>ORGANIZE option. Since we are going to select a surface (white colored), select the surfs option or change to surfs if element or some option presents, also verify that dest component is Bracket2 (where white colored surface is going to be stored).

8) To repersent this 2D element into 3D we need to assign thickness for them. To help the former, we need to assign material and properties for the two brackets.

Right click on the tab bar, use 1) Create>material ( to create material).

2) Create>Property (to create properties).

Since we have two brackets, we are creating two properties for each brackets.

Material is assumed as Steel, also apply Youngs modulus and Poission ration value.

Card ID is taken as PSHELL for OPTISTRUCT profile, since we are representing 2D shell elements.

9) Next we have to apply the assigned material to each bracket. Select the Bracket1 as shown below, we will get the table for Bracket1 in the tab bar (Left bottom). In that update for material section as steel.

10) Also update property for Bracket1, by selecting bracket1 in select property pop up.

In the same way apply material and property for Bracket2 also by repeating the previous two steps.

11) Washer split is given, for all the holes as mentioned below. For this use, Geom>Quick Edit>washer split. Give the required offset value, I have taken 5mm offset.

12) Mesh the parallel brackets. Use 2D>automesh.

Select the surfs option, and select displayed or all so that the entire model in graphics area gets elected for meshing. Then hit the mesh button.

Element size taken is 8mm.

RIGIDS & Rbe3 ELEMENTS

Rigids are also called Rbe2 element and hae infinite stiffness.

Rbe3 elements can be moved on the required direction based on the application of load.

13) As per the requirements for the challange, create Rbe2 links on the nodes of the hole selected on the upper bracket. Use 1D>Rigids to create Rbe2 links.

Select the dropdown arrow to select multiple node, since we are selecting huge number of nodes for creating rigids link. Make sure calculate node option is used for creating rigids link as mentioned below.

dof1, dof2, dof3 - they repersent translational degree of freedom

dof4, dof5, dof6 - they represent the rotational degree of freedom

Enable the required dof as per the conditions given. Here for the first hole I have enabled all transational degree of freedom.

14) Similarly repeat the above procedure, to create Rbe2 link on the lower bracket also.

15) Create Rbe3 links on the second hole of the upper bracket. Use 1D>rbe3

Here I used by path option to select the nodes. After selecting nodes option, on the pop up shown right side select by path option. The main advantage by using path is if we select two nodes in a particular path, remaining all node between the selected nodes will be selected as show below.

After selecting the nodes hit the create button to create rbe3 links. For dof I have enabled every dof.

16) Similarly create rbe3 links on the lower bracket by repeating above procedure.

17) Create rbe3 links on third hole with x and y dof enabled (as per condition).

As the same way, create rbe2 links, as mentioned below on both holes on upper and lower bracket.

18) Give mass of magnitue 10 to the created links by above procedure. Use 1D>Masses

Select the nodes at which mass have to be applied & hit create button.

19) Join the two bracket by applying spring element as shown below. For this use 1D>Springs. Here CELAS1 represents the spring element.

20) Now we have to create cross sections for the beam bar & rod which can be done by hyperbeam. Use 1D>Hyperbeam

In Standard selection type, select the required cross you want and select create button it will guide you to a new environment, where we can assign parameters for the cross section. By selecting the drop down in standard selection type the below mentioned pop up will be visibile. From this required type can be selected.

Below mentioned environment will appear as soon as we hit the create button after selecting the section type. For my case I selected box for rod.

The parameters for the box can be defined in the table bottom.

21) To create another new cross section, right click on the white space and select Create>Standard Section>Hypermesh as shown below. For my case I\'m selecting I section for beam and the parameters for that is defined at bottom.

Similarly create cross section for bar element as show below and define their respective parameters.

22) Create rod element for the holes as mentioned. Use 1D>rods.

Select the nodes of both upper and lower bracket of first hole and change the elem type to CROD and hit the update button.

23) Create Beam element for the holes as mentioned. Use 1D>bars.

Select the nodes of upper and lower bracket and for orientation select the green node and blue node for N1 and N2 respectively for cross section.

Update the elem types as CBEAM and finally hit the tab button to create beam element.

24) Similarly create bar element by repeating the above procedure and update elem type as CBAR.

25) Create properties for bar rod & beam by right clicking on the tab bar and select Create>property

26) Assign the properties for rod by selecting on it and making the card image as PROD. Also udpate beamsec to rod which we created in hyperbeam environment.

Proceed the same way to assign for beam and bar. Also make a note of Card unit for beam & bar.

27) Update the assigned properties to rod. Use 1D>rods. Make use of update option instead of create to update properties to rod.

Select the property box and a pop up will emerge, in that select rod as shown below and hit the update button.

28) Update the assigned properties to beam. For this use 1D>bars. Select update option.

Select beam element to be updated

Go to property box & select the empty space and a pop up will emerge, in that select beam as shown below.

After selecting beam section refered in green color, again HM will show us different option in which select property and elem type and hit the update button.

29) In a similar way update cross section for bar element also. Make sure elem type is CBAR.

29) Here 1D detailed element representation is used to view the applied cross section to the respective element.

These three structures represents the cross section applied to each beam rod and bar element.

RESULT:

Thus the above mentioned procedure is folowed to complete the project and the final result is :

CONCLUSION:

Thus by using these project various features of 1D element like rod, beam, bar and their properties, spring elements, importance of midsurfacing application of cross sections to the beam and rod elements, properties of rigids and rbe3 element and special edit option like washer split were explored in depth and learnt successfully.