Week 6

Objective: To apply different types of connection techniques for the given Rear door FE model using the options under NASTRAN deck.

FE model file of rear door:https://drive.google.com/file/d/1poIryIllMcmnRr-Rrn54pa_C8yHavooG/view?usp=sharing

Procedure:

• The given FE model is in .nas format. So, to open this file in ANSA workbench, follow File>Input>Nastran
• Check for the regions where connections need to be implemented
• Set seperate PIDs for parts throughout the model
• Start making connections from one end and move to other end
• All single holes in the model are made rigid using RBE2 elements connection under NASTRAN deck (RBE2 many nodes)
• For matching holes, assign a Center of gravity point for one of the hole using Topo module>Points>On COG
• Change this point into Bolt connection by following Assembly>Convert>3D points>Connection type>Bolt
• Using Connection manager with FE Rep type-[Bolt], by assigning proper P1 & P2, a bolt connection is made wherever a bolt is necessary
• Also, rigid connections for matching holes can be done using 2node RBE2 or a cluster RBE2 connection
• At latch area, the 2node RBE2 is modified in CM as 12345, because a rotational movement about Z-axis is required for opening & closing of door
• Spot weld connection at required regions are made by assigning a COG point and making it as a spot weld connection type and by using connection manager with FE Rep type-[RBE3 HEXA RBE3], giving proper values of search distance, setting RBE Pinflags-123456 and a PSOLID ID, a spot weld connection is established
• For door handle, a RBE2 rigid connection is made at both ends and a CONN Mass is assigned at the center master node which connects two master nodes of both ends
• NAST. deck>Elements>CONMi>CONM2>Nodes
• The value of mass should be given in terms of tonnes(100gms=0.0001tonnes)
• The glass windows connections are done using CBUSH elements
• The perimeters of glass are made to curves using Feat2Curve option in perimeters of mesh module
• These curves are converted to Spot line each, one after another
• In Connection manager, using RBE3 CBUSH RBE3 as FE Rep type, and by assigning P1, P2, search distance value with switching on keep all branches option, the connection is established
• In PBUSH ID, 6 stiffness values need to be assigned (K1=K2=K3=0.001;K4=K5=K6=10)
• All the orientaions of CBush are made similar to that of Global coordinate system using CBUSH property card (Orient-with coord;CID=0)

Image for Reference:

• Spot weld, bolt, cluster, and bush connections

Worked model Link: https://drive.google.com/file/d/16DTJ9E0m_r8LVXuDdygrx2XUf3zrVN1n/view?usp=sharing

Learning Outcomes:

• Rigid connections, Spotweld connections, CBUSH elements
• Assigning mass and degrees of freedom

Conclusion:The connections in rear door FE model are made with appropriate type of connections wherever they are required.