Week 9-Creation of 1D Connectors Challenge

CREATING 1D CONNECTORS IN HYPERMESH

OBJECTIVE:

• To mesh the given geometry according to quality parameters
• To create connectors at the different joints and attach the various parts in the given model

Quality Criteria Used:

Target Element size - 5 Units

S.No	Quality Criteria	Value
1	Aspect Ratio	5
2	Skewness	45
3	Warping	15
4	Taper	0.5
5	Min. Length	2 Units
6	Max. Length	8 Units
7	Min angle Quad	45
8	Max angle Quad	135
9	Min angle Tria	30
10	Max angle Tria	110
10	Tria %	15

Create connectors and Attach the various parts of the given model as per specified below.

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 2 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
9. Rest all the component left Join them with suitable connectors

PROCEDURE:

• Import Geometry: Go to File >> Import >> Model/Geometry

different component of wireframe assembly are shown below :

Fig: Front Truss 1

Fig: Front Truss 2

Fig: Reinforcement Plate

Fig: Right Rail 1

Fig: Right Rail 2

Fig: Left Rail 1

Fig: Left Rail 2

Fig: Rear Truss 1

Fig: Rear Truss 2

Mesh Generation:

Mesh each surface individually according to quality parameters

Improve mesh flow and clear off elements and opposite trias

The model is cleaned up using the autocleanup option and by manual efforts. Meshed with proper mesh flow. The mesh type is mixed and element size is taken as 5 mm. It is a 2D mesh since the entire model comprises extracted midsurfaces already.

Meshed model and quality criteria under which it is meshed, shown in images below.

Connection Deployment:-

Connectors are geometric entities, which are primarily used to represent the CAD geometric connection in terms of FEA. Connections can be created as a spot-weld, seam-weld, adhesive, bolts and masses. A realized connector will be considered as the successful representation of a CAD model in preprocessing and the connecting parts can be considered as connected.

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

The first connection that needs to be made is between Right_Rail_2 and Front_Truss_1 which is a Seam-Quad(angled+capped+L) connection.

• Select 1D/2D > Connectors > Seam option.
• Now select the location, where the Weld has to be created, by clicking the “node path”.
• Tick the checkbox of “retain nodes” option, to retain the position of the nodes, while creating and realizing a connector.
• Specify the “spacing” value and select the “comps” option under “connect what”, in order to create the weld between those two components.
• Specify the “tolerance” value, based on the distance between the two components.
• Select the type as “seam-quad (angled+capped+L)”.
• Click on the “create” button, to create the seam weld.

There are some parameters that a capped seam weld connection contains, so those need to be taken care of -

Spacing:- It is generally kept equal to the target element length of the meshing.

Tolerance:- It is the search radius around a node that the software looks for any component to connect with and generally it is kept either equal to or greater than the distance between the two components that need to be connected with each other.

Weld Angle:- Angle between the normal projection of the nodes and slant length of the weld element. It is recommended to define weld angles between 0 and 90 degree.

Cap Angle:- Angle between the normal of the first slant weld element and its adjacent side element. To define seam weld for 0 to 45 degree cap angle, it is recommended to select ≤10 degree and for the 45 - 90 degree cap angle, it is recommended to select ≥75 degree.

Runoff Angle:- Angle between the normal of the first slant weld element and its adjacent weld elements.It is recommended to define weld angles between 0 and 10 degree.

2) Left_Rail_2 & Front_truss_1:- Quad elements

• Select 1D/2D > Connectors > Seam option.
• Now select the location, where the Weld has to be created, by clicking the “node path”.
• Tick the checkbox of “retain nodes” option, to retain the position of the nodes, while creating and realizing a connector.
• Specify the “spacing” value and select the “comps” option under “connect what”, in order to create the weld between those two components.
• Specify the “tolerance” value, based on the distance between the two components.
• Select the type as “quads”.
• Click on the “create” button, to create the seam weld.

3) Front_truss_2, Front_truss_1 & Right_Rail_1:- Spot weld with 2 Layers and 5 mm Diameter

• Select 1D/2D > Connectors > Spot option.
• Now select the location, where the Weld has to be created, by clicking the “node list”.
• Tick the checkbox of “retain nodes” option, to retain the position of the nodes, while creating and realizing a connector.
• Specify the “spacing” value and select the “comps” option under “connect what”, in order to create the weld between those two components.
• Select the number of layers(Number of Components) to be welded, under “num layers” option.
• Specify the “tolerance” value, based on the distance between the two components.
• Select the type as “weld”.
• Click on the “create” button, to create the spot weld.

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

• Select 1D/2D > Connectors > Seam option.
• Now select the location, where the Weld has to be created, by clicking the “node path”.
• Tick the checkbox of “retain nodes” option, to retain the position of the nodes, while creating and realizing a connector.
• Specify the “spacing” value and select the “comps” option under “connect what”, in order to create the weld between those two components.
• Specify the “tolerance” value, based on the distance between the two components.
• Select the type as “hexa (adhesive)”.
• Click on the “create” button, to create the seam weld.

5) Rear_truss_2 & Right_Rail_2:- Bolt Connector and 6) Rear_truss_2 & Left_Rail_2:- Bolt Connector

In order to create a Bolt connection, if hole is not present in the components, we have to locate a center node so that hole can be created at that place as shown below.

• Now click on the 1D/2D > Connectors > Bolt option.
• Under “location”, select the node, which we created already to establish the bolt connection.
• Then select the “comps” option under “connect what”, in order to create the weld between those two components.
• Select the number of layers to be welded, under the “num layers” option.
• Specify the “tolerance” value, based on the distance between the two components.
• Select the type as “bolt (general)”.
• Click on the “create” button, to create the Bolt Connection.

6. Rear_truss_2 & Left_Rail_2:- Bolt Connector

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

• Select 1D/2D > Connectors > Spot option.
• Now select the location, where the Weld has to be created, by clicking the “node list”.
• Tick the checkbox of “retain nodes” option, to retain the position of the nodes, while creating and realizing a connector.
• Specify the “spacing” value and select the “comps” option under “connect what”, in order to create the weld between those two components.
• Select the number of layers(Number of Components) to be welded, under the “num layers” option.
• Specify the “tolerance” value, based on the distance between the two components.
• Select the type as “rigid”.
• Click on the “create” button, to create the spot-weld with rigid elements.

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

• Select 1D/2D > Connectors > Spot option.
• Now select the location, where the Weld has to be created, by clicking the “node list”.
• Tick the checkbox of “retain nodes” option, to retain the position of the nodes, while creating and realizing a connector.
• Specify the “spacing” value and select the “comps” option under “connect what”, in order to create the weld between those two components.
• Select the number of layers(Number of Components) to be welded, under “num layers” option.
• Specify the “tolerance” value, based on the distance between the two components.
• Select the type as “spring”.
• Click on the “create” button, to create the spot-weld with spring elements.

9) Other Connections:-

Rear_Truss_1 & Rear_Truss_2:- RBE2 Elements

Go to 1D > rigids > independent - calculate node, dependent - multiple nodes > elem types - RBE2 > dof > create. Nodes are selected and elements are created separately for both the holes and then select dependent - single nodes to create the bolt stem connecting dependent nodes of the both RBE2 elements with each other.

10) All the other connections are made with the Seam-weld option.

• Select 1D/2D > Connectors > Seam option.
• Now select the location, where the Weld has to be created, by clicking the “node path”.
• Tick the checkbox of “retain nodes” option, to retain the position of the nodes, while creating and realizing a connector.
• Specify the “spacing” value and select the “comps” option under “connect what”, in order to create the weld between those two components.
• Specify the “tolerance” value, based on the distance between the two components.
• Select the type as “weld”.
• Click on the “create” button, to create the seam-weld.

RESULTS :

• The given model is meshed and connected using seam, spot and bolt connections and the final connected model is shown below.