Week 9-Creation of 1D Connectors Challenge

OBJECTIVE:
To mesh the given geometry and create 1D connectors at desired locations using Hypermesh.

The following connections have to be realized in each respective component

1. Right_Rail_2 & Front_truss_1:- Seam-Quad(angled+capped+L)

2. Left_Rail_2 & Front_truss_1:- Quad elements

3. Front_truss_2, Front_truss_1 & Right_Rail_1:- Spot weld with 3 Layers and 5 mm Diameter

4. Front_truss_2, Front_truss_1 & Left_Rail_1:- Hexa (Adhesive)

5. Rear_truss_2 & Right_Rail_2:- Bolt Connector

6. Rear_truss_2 & Left_Rail_2:- Bolt Connector

7. Right_Rail_1 & Right_Rail_2:- Spot-weld with Rigid Elements

8. Left_Rail_1 & Left_Rail_2:- Spot-weld with Spring Elements

PROCEDURE:

Setting up model

• Import the .hm model and the connector points in the model tree are hidden while meshing
• Each individual component is separated and meshed seperately.
• If required, the components can be cleaned for topological errors and defeatured using manual or autocleanup method.
• To clean geometrical errors: Geom - autocleanup - set parameters - clean

2D surface Meshing & Mesh refinement

• To generate a shell mesh over each component:
• 2D - automesh - surfs (displayed) - target length =5 - specify elem type and order - mesh
• However to achieve a perfect mesh without quality errors the comp is sectioned into different surfaces using surf trim option and meshed separately.
• Since volume tetras arent being generated, the surfaces can be meshed with quads majority
• Similarly, symmetrical components can also be trimmed about the mid point and meshed and reflected about the central axis
• Finally all components have been meshed using 2D elems (trias and quads)

Assigning property card

• A single property and material card is added for every component.
• Assuming every comp has the identical thickness and material, a single card is added to each
• To create a material card: name =steel - type=ISOTROPIC - card=MAT1
• Then the necessary material values like poissons ratio, youngs mod etc.. are specified
• Similarly a new property card is created with the PSHELL card image and the above mat card is assigned to it.
• The thickness of the comp are also specified in the property card.
• Each card is assigned the property card which is linked to the material card.

1D Connections

1. Seam-Quad(angled+capped+L)

For: Right_Rail_2 & Front_truss_1

• To create a seam weld: Connectors - seam
• Select the nodes (by path) on one of the component
• tolerance = Specify the search distance (10mm)
• Select the two components and keep the imprint check on
• weld type is set as seam-quad (angled+capped+L)
• The weld angle can be altered but an angle of 60 or 45 is widely preferred based on the alignment of the two components.
• The spacing is set a 5mm. Spacing defines the distance between the two adjacent weld elements

2. Seam- Quad elements

For: Left_Rail_2 & Front_truss_1

• To create a seam weld: Connectors - seam
• Select the nodes (by path) on one of the components
• tolerance = Specify the search distance (10mm)
• Select the two components and keep the imprint check on
• weld type is set as quad and the spacing (distance between the two adjacent weld elements) is kept as 5mm

3. Spot weld with 3 Layers and 5 mm Diameter

Front_truss_2, Front_truss_1 & Right_Rail_1

• To create a spot weld: 2D - connectors - spot - type=weld
• Select all the required nodes where the location of the spot weld has to be placed.
• Then select all the 3 components
• Specify a diameter of 5mm and number of layers as 3.
• NOTE: Since the layer is set as 3, a minimum of three components have to be selected and in case only two components are present then the layer has to be set as 2.

4. Hexa (Adhesive)

For: Front_truss_2, Front_truss_1 & Left_Rail_1

• To create a seam weld: Connectors - seam
• Select the nodes (by path) on one of the component
• tolerance = Specify the search distance (10mm)
• Select the two components and keep the imprint check on
• weld type is set as hexa (adhesive) under the weld type category.
• The strips and coats of the weld can be altered. In this case, the strip is set as 2 and a single coating is specified

5. Bolt Connector

For: Rear_truss_2 & Right_Rail_2

• To create a bolt connector: Connectors - bolt
• Specify the location of the bolt by selecting two single nodes at a certain distance in one of the component since two bolt connectors are being realised.
• Select the two components which has to be fixed by the bolt.
• Select the option to create a hole to define the bolt as a physical element (Note that this will modify and alter the neighbouring mesh )
• Specify the search length (about 10mm)

The realised bolt connection is shown below

6. For: Rear_truss_2 & Left_Rail_2

7. Spot-weld with Rigid Elements

For: Right_Rail_1 & Right_Rail_2

• As similar to previous spot weld creation, this spot weld is created using rigids instead of weld
• To create a spot weld: 2D - connectors - spot - type=rigids
• Select all the required nodes where the location of the spot weld has to be placed. (by path)
• Then select all the 2 components
• Specify the diameter and number of layers as 2 (since only two components are present)

8. Spot-weld with Spring Elements

For: Left_Rail_1 & Left_Rail_2

• Similarly as done for the previous case, here the spot element type is set as spring instead of rigid or weld

9. For other components

CONCLUSION:

Hence every components have been meshed and required connections have be defined and sucessfully realized.

Finally the entire connections and meshed components are shown below