Week 6
CAR REAR DOOR CONNECTIONS
AIM:
This model is included with car rear door that should be given connections( like bolt, washers, spot welds, seam welds, clusters etc., ) where it is needed so that it should be resulted in better fixing of door without any loose parts.
PROCEDURE
1.GEOMETRY CLEANUP:
Basically in this challange the FE model is given that should be further taken to make the connections after any geometry checks.
The basic thing when a model is dumped into the ANSA is to check the geometry to find if any errors were present. The geometry checked model is shown in the image below.
Now in previous challanges we are gone through the topo, mesh and volume modules but here for giving connections between the different parts we are going to use the NASTRAN deck where it consists of tools like elements, grids, boundary conditions and coordinates that are useful in the connections. Below is the image showing the contents cover under NASTRAN deck.
2.ANALYSING:
The things that should be done after geometric checks was analysing the connections that where it should be needed like the bolt connections where rigid fixing of two elements with washers as a RBE2( rigid body element) and without washers as cluster RBE2. The main critical parts of connections in the door model is the glass which is the reason for regulate the climate connection between inside and outside atmosphere and the door handle has to be mentioned with the mass in its PID that is applied on the handle.
3.CONNECTIONS:
Firstly in this model there is a sequence of operations in creating the types of connectiions.
BOLTED CONNECTIONS :
For the bolted connections if it consists of only rigid elements that should be fixed it is connected with rigid body elements many nodes (RBE2) with a bolt connection, for this a COG point is created between one of the element and it is converted to bolt type connection then that should be given bolted vconnection by using connection manager selecting part 1, part 2, etc., and maximum four parts can be connected together as a rigid or cluster. Now here cluster connection is also a many node RBE2 connection type but this type of connections are given to those where mechanism is situated.Cluster connection can also be given between maximum 4 elements.
Below is the image shown for marking the tools used for rigid and clusted bolted connections.
Below is the image shown for created bolted connection rigid and cluster types.
The iimportant part of door connections were hinges where door is hinged and can be rotated in an axis that should be in a constrained manner by defining the degrees of freedom(DOF) 12345 and 6 is non constrained as door rotates in Z-axis in this given model and the connection is done with a stem connection between the hinge part and that is shown below in the image.
The door handle connection consists of a different type of representation where we have to specify the amount of mass we are going to apply on the handle bar which is called as con mass that should be given in weight of tonnes.
Here the mass applied on the door is given as 250 grams and the same should be represented in tonnes.
1000 gm = 1 KG
1000 KG = 1 tonne
250 gm = 0.00025 tonnes
The below image shows the door connection creation.
SPOT WELD CONNECTIONS:
There are some specific connections where the two surfaces of the elements overlap, that kind of connections are given with a sppot weld connections when it is necessary to do it. the below image shows the spot weld connections which are created with using COG points-covert them to spotweld points-given connections using connection manager by RBE3-HEXA-RBE3 type of connection.
WIND GLASS CONNECTIONS :
When coming to the wind glass conections this is the most critical and important connections through out the door model as this stands between the inside and outside the atmosphere for the air circulation.so coming to the connections for this first the glass should be given a fixed representation in ANSA so that it can be shown as non loose part. The glass perimeters are guided with the weather strips so that it has a definite air leakage proof. Now when taking up the connections for this first we have to represent these weather strips using a CBUSH elements in the tools so that the glass is exactly situated between the weather strips. For creating connection firstly we have to create a feat to curve along perimeter of the glass and coverting it to a spot line. Then the using the spot line the part 1 and part 2 is selected in connection manager with a RBE3-CBUSH-RBE3 connection type and PID is established then connection is given between the glass and the outer panel using CBUSH connection that resembles the weaather strips.
The below image shows the connections of weather strips using CBUSH connection:
After the CBUSH connections are given the each CBUSH connections should be assigned from local coordinates to global coordinates for a better viewing of the connections. First the orient should be enabled and also CID should be enabled then by selection all the CBUSH connections in the elements they can be changed to global coordinated by assigning the CID to zero. The image regarding this is shown below.
NEW THINGS LEARNED:
- Learnt to operate the NASTRAN deck tools
- Learnt to create bolt, cluster connections.
- Learnt to create seam weld, spot weld connection, CBUSH connections.
- Learnt the differnce between real life and software based connection systems.
- Learnt to analyse the connections that where they must to be deposited.
- Lerant lot more things to explore by trial and error.
CONCLUSION:
All the connections were given with atmost care and intrest that were necessary at required regions and also lot more things can be learnt from the connection systems.
LINK FOR ABOVE PROCESSED MODEL: