Week 6

Connections for the given Rear Door Model

Aim:

To connect the various components of the given rear door model using the connection tools in ANSA.

Abstract:

The connections for a model are given in ANSA so that the model should not fail for quality while running a simulation and to give a resembling 1D node connection weights for actual working for a particular function. A Rear door has various components and mechanisms which are to be connected rigidly without blocking the essential mechanisms of the door. The given model has provisions to give bolt connections and some spot welds in few areas where the components are attached firmly without any free movement. A bush connection around the window is given for isolating the temperature inside the cabin of the car.

Methodology:

• The given model has many components and the property IDs are to be created for each part.
• Start giving connections in all required areas and PIDs are to be created for the connections.
• The degrees of freedom are to be taken care of so that the connections in a few areas will not block the movement mechanism of the door.

Introduction:

A car door is a type of door, typically hinged, but sometimes attached by other mechanisms such as tracks, in front of an opening which is used for entering and exiting a vehicle. A vehicle door can be opened to provide access to the opening, or closed to secure it. These doors can be opened manually, or powered electronically. Powered doors are usually found on minivans, high-end cars, or modified cars.

Fig 1: Actual Rear door.

Fig 2: Front view Fig3: Rearview

Procedure:

• First, start creating the PIDs for each part for easy identification of the components.
• Start giving the connections in required areas. The following tools are used for connecting the components.

1. RBE2 and RBE3 connections:

RBE2 and RBE3 are rigid links in FEM used for load transfer. These elements impact will not deform as they are considered to be infinitely rigid and the sole purpose of these elements is to transfer the loads between the grid points or nodes. RBE2 transfers the loads in such a way that all the slave (dependent) nodes have zero relative deformation after the loan application. Whereas RBE3 transfers the load using a weighted average of slave nodes(independent nodes) position. The procedure to give the RBE 2 and RBE 3 connections are given below.

a. RBE 2:

Select the nodes where the bolt connection is to be done. After selecting the nodes for connection, a master node is created concerning all the selected slave nodes i.e., the master node indicates the bolt connection and the load formed in that particular area. The connection PID is to be created so that the properties of the connections are mentioned in it.

Fig 4: Connection to be given

Fig 5: Selecting the slave nodes.

Fig 6: Creating the master node.

Fig 7: Creating a fixed connection

To create connections between two components which are far way than usual, the two-node connection option is to be used so that it creates a steam connection between the two nodes i.e., to resembles the steam part of the screw.

Fig 8: Creating the two-node connection

Fig 9: Node selection window

Fig 10: Connection PID

Fig 11: Created connection.

In a door, the hinge connection should be given in such a way the opening and closing of the door should be free. In this situation, the degree of freedom for rotation in the z-axis is to be free. So the degree of freedom for the hinges is to be restricted to 5 instead of 6.

Fig 12: Info of the selected connection

Fig 13: A changed degree of freedom

b. Creating handle load using RBE2 connection:

In the given model the hand to open and close the door is assumed as a transparent load by creating a master node in between.

Fig 14: Creating a master node in place of the handle

• First, the open regions are to be connected using the RBE2 Thus two master nodes are created in the gaps provided. Then connect the two master nodes so that the main master node is created in between so that to resemble and to create a weight on the main master node.
• Use the conmass option to add weight to the master node.

Fig 15: Conmass option

• Select the node which is required to add mass. The weight of the handle bar is assumed as 100g. So the mass of the handle bar is represented in the property card of the master node.

Fig 16: Selecting the master node.

Fig 17: setting the mass ‘M’ for the selected node

Fig 18: created master node.

Thus the master node is created resembling the handle weight.

2. RBE 3 connection:

In this challenge, the RBE3 connections are used for creating the spot weld connections and the bush around the window used to seal the window opening. The various connections and steps are used to create RBE3 connections.

a. Spot welds:

• Spot welding (or resistance spot welding) is a type of electric resistance welding used to weld various sheet metal products, through a process in which contacting metal surface points are joined by the heat obtained from resistance to electric current.

Fig 19: Spot welding

• In ANSA, spot weld is formed by creating a 3D COG point where two surfaces are to be welded. After creating a 3D point in the required area, the point is to be converted to a spot weld option so that to create a connection between two surfaces.

Fig 20: Selecting the area to be spot welded.

Fig 21: Creating a 3D point

Fig 22: Options to convert to connections

Fig 23: Converting 3D point to spot weld point

• The spot weld point is to be selected through the connection manager and the two surfaces which are to be connected should also be selected as P1 and P2 i.e., part 1 and part 2.

Fig 24: Selecting and Creating the spot weld through the connection manager

Fig 25: Connection manager window

Fig 26: Selecting the parts to be welded

Fig 27: Entering the parts to the connection manager for welding

• The spot weld in this challenge is used for creating hexa connection, so the RBE3 HEXA RBE3 option is to be used.

Fig 28: Selecting RBE3 HEXA RBE3 option for welding

• Set the search distance as required and a new PID for all the spot welds in the model is to be created.

Fig 29: Entering the dimensions and PID data

• Apply and realize the connection so that the connection is created.

Fig 30: Created spot weld connections

b. RBE3 CBUSH connections:

A CBUSH connection is used for generating spring and damped connection between two components. In this model, the CBUSH is used for connection between the window and the frame of the door, which resembles a rubber cable connection around the window to the window frame. The rubber cable connection is usually used for isolating the inner temperature of the cabin of the car.

Fig 31: CBUSH of the window.

• To create a CBUSH connection around the window glass first, a curve should be created around the glass by using a con to curve option so that the curve is created with respect to the con of the glass.
• A second curve is created at the lower part of the windshield so that to create a support for the outer panel and the inner panel of the door.

Fig 32: Selecting the copy option

Fig 33: setting the distance and direction where the curve has to be created.

Fig 34: Transformation option window.

Fig 35: create a second curve.

• The curves must be converted to a spot line for creating the connection.
• Then the spot line must be converted to CBUSH connection through the connection manager option. Select a curve and select the parts to be connected. Set the RBE3 CBUSH RBE3 option and set the search distance and create a new PID and apply and realize to create a CBUSH connection.

Fig 36: Connection manager data

Fig 37: created CBUSH connection

• The created CBUSH connection shows the vector lines i.e., 1, 2, 3 which represents the pressure required to isolate and connect the windshield.

These are the connections used for connecting the particular model. Some of the important connections are:

3. Welding:

Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature metal-joining techniques such as brazing and soldering, which do not melt the base metal.

• In ANSA the weld is created by taking the data of the CAD model weld in the form of a curve which represents a weld length.

Fig 38: Weld in CAD Fig 39: creating a curve for seam weld

• The curve must be created into a seam line so that it helps to create a seam weld connection for the two surfaces.

Fig 40: converting curve to a seam line.

• After converting to a seam line, select the seam line to create a connection in the connection manager. The following weld should be an overlap shell weld. So select the required two sheet metals to be connected and set the FE representation type to overlap shell. Set the required data such as the search distance, base sheet, set length, width, and the weld PID.

Fig 41: Connection manager data.

• Apply and realize the connection so that the connection is formed on the two sheet metals.

Fig 42: Overlapped shell weld connection

• Welds in few areas are used for connecting the holes and tubes which are a little complicated in the real world. In ANSA these types of welds are represented in the form of Y-JOINT SHELL. The weld is round curves and should provide a rigid connection for the two components.

Fig 43: Y-JOINT SHELL connection

Result:

Thus connecting the components for the given rear door model is completed using the tools in ANSA.

Fig 44: given model rearview Fig 45: given model front view

Fig 46: Connected model rearview. Fig 47: Connected model front view

Learning Outcomes:

• Learned to use RBE2 and RBE3 connections
• Learned to give a seam weld overlap shell and Y- JOINT shell
• Learned to give CBUSH connections.
• Learned to give resembling weights to a master node.

Conclusion:

All the required connections are given using various tools and can be proceeded for simulation.

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