Challenge

Week 6 - Creating connection for Rear door

Aim :

The given Rear door FE model, Perform suitable connections between various parts .
Create and Apply different PIDs for different components.

Procedure :

First we need to import the model as shown. Then the entire model will be separated into different PIDs
This process can done by using Set PID > Select Macro / shells and assign the property
This process is repeated until PIDs have been assigned for every component in the model.

BOLT CONNECTION

We can start with RBE2 connections . This option can be done by NASTRAN DECK > ELEMENTS > MANY NODES
We deploy the 'MANY NODES' option . This is merely done by selecting the two sets of nodes surrounding the holes and letting the alogrithm create a master node and form connections . This also called as cluster node RBE2

Next we moved two node RBE2 connection . this option specially used in hinge area due to hinge joint requires yaw movement
And, such will have 5 D.O.F s fixed . Meaning , When defining it during the two nodes RBE process, care must be taken to ensure the value of 'CM'is 12345 to allow the movement

There is another way to assign bolt connections which becomes especially useful in cases where there are more than 2 layers that requries connecting.
This will involve using the connection manager . Before that , we need to create a COG point in one of the holes from a layer in the middle
Using the POINT > ON COG . Then point needs to be converted into a bolt using the convert tool

After converting the point into a bolt , the connection manager is accessed and the bolt point selected
In connection manager we need to assign the P1,P2 & P3 by selecting the PIDs
Then FE Rep type needs to be 'BOLT' . The search distance can be assigned according to the distance from the bolt point.

Now into the door handle , in this region , we need to create a connection that applies a mass . For this , we need to create RBE2 nodes in either handle holes separetly
Again , using the same tool , the two master nodes for either handle hole is selected and another connection is created , with the alogrithm assigning a new master node at the centre of this connection
Now , we make use the Con Mass tool accessible through ELEMENT > CONMI > NODES .

Then the priviously mentioned master node is selected . This is where the mass of the handle will be concentrated . After proceeding let us assign the mass.

WELD CONNECTION

We shall be looking at seam and spot weld connections . in the case of seam welds , the basis is creating the weld locations from curves basis is creating weld location from curves derived from the particular feature
We using the MESH MODULE > PERIMETERS > FEAT2CURVE option . this will let us select the edge and derive a curve
Then using the convert tool that was used earlier, the curve can be converted into seam line

Again , as before we make use of the connection manager .The seam line selected and proceed and assign P1 and P2 are selected .
The FE Rep type here would be OVERLAP shell since both layers are parallel to each other

Next Spot welds , we shall be making use of the COG tool again to create 3D points . These 3D points are then converted into 'SPOT WELD' .
After conversion, its the same process of accessing the connection manager and assigning properties
This time , since it's a spot weld , the FE Rep type would be RBE3 >HEXA >RBE3 . then assingn the P1 and P2
A PSOLID will be need to be created and assigned.

CBUSH CONNECTION

The next type of connection would be that of CBUSH RBE3 elements, which will be used wherever window weather strips are involved.
To begin , the perimeter of the glass components is used to create curves. for this, PERIMETER > FEAT2CURVE tool is used to select and create them
Selecting the curves , they can be converted into SPOT LINES using CONVERT > CURVES tool.Each curve need to be selected separetly and converted

After converting them , we avail the help of the connections manageer again to create these CBUSH connections . The process will be repeated for each curve
Then we need to select the P1 and P2 as usual . Need to assign the spacing value . The FE Rep type would be RBE3-CBUSH-RBE3
We can proceed to create a BUSH ID . In the PBUSH ID. The ID will be requires 6 stiffness values and they can be entered

FINAL MODEL IMAGE

LEARNING OUTCOMES :

Learned about various connections available in the NASTRAN deck
Learned to convert curves and points into connection lines / points
Learned to assign properties to connections and edit connections as per requirements
Learned about the concepts of weather stripping and its importance, along with the concept of tailor welds

Conclusion :

Suitable connections were deployed between various components in the rear door model after PIDs were assigned to each component.

Ship work like this
in your own course.