Pre-processing rear-door mesh assembly connections

JORGE LOZANO

Preprocessor for Structural Analysis using ANSA

Pre-processing rear-door mesh assembly connections

Objective

This week, the connection of the front door is shown in detail and the different types of connection techniques along with different 1D elements.

Now for the given rear door FE model, apply the same technique and the elements to implement the connections

Theory

The term “assembly” in ANSA involves numerous actions that will finally lead to the creation of an inter-connected structure. Characteristics of this structure are:

-The hierarchical organization of all components in the ANSA Parts Manager which represents the CAE model tree structure

-The welding of standalone components with suitable FE-representations

-The connection of standalone components or sub-systems so that the kinematic conditions that physically exist between them are modeled with suitable FE-representations.

In most applications, all three characteristics co-exist in the final model. However, ANSA can also handle any of these aspects individually.

Since in an assembled model the individual components are connected in various positions and with various welding/assembling techniques, the tools which will carry-out such tasks must be able to easily interpret the information provided by the user into the desired FE-representations.

The tools used in ANSA for this purpose are the Connection Manager, the connector entities, the “Adhesive” function and the “BOLT” function. Assembly specific tools are gathered in the “Assembly” menu and can also be accessed through the “Assembly” toolbar.

F.1 Assembly tools.

The following represents the connection types and tools that could be useful while representing it into the Ansa software.

F.2 Connections table.

Spot-weld points

Spot-weld points are the most common connection type and are used to model welding points. Their basic attributes are listed in the table below:

F.3 Spot-weld- characteristics.

Bolts

Bolts are used to model bolt-connections. Subsequently, they can attach on openings or nodes and they can also drill holes on shell structures, if necessary.

F.4 Bolts characteristics.

Seam lines

Seam lines are used to model arc welds. Their basic attributes are listed in the table below:

F.5 Seam lines characteristics.

Procedure

At first is to open the structural shell mesh, obtain an overview of all parts and assemblies that must be connected to perform, as in F.6.

F.6 Shell mesh rear-door geometry.

One important condition that must be taken care of before performing any assembly connections are to select each part separately and adjust an ID unique to each one of them to facilitate the selection when performing the connections, and to visualize the assembly better.

F.7 PID data assembly.

While checking the assembly shell mesh, there were several inconsistencies and visual parts that were missing, as in F. 8. After that by selecting each hole with COG hole tool, and the bolt connection to automate the assembly connections, all hole were performed as connections and spiders like connections in which several shells or faces are connected to be as a fixed condition along their degrees of freedom

F.8 Geometry error in assembly part.

In F. 9 the missing part and connections were performed to obtain a good bolt connection along the 5 degrees of freedom due to the angle in which the door can open, seeing these two connections with these limitations of degrees.

F.9 Completed and fixed assembly connector.

As in F.10 several assembly parts are shown to perform a spot-weld, bolt, or steam line connections which are the connections performed in this assembly. In F.11 the steam line characteristics and properties are shown in which the window shows the orientation of the connection between the window and the shell element pats, as RBE3-CBUSH-RBE3 connection type.

F.10 Internal rear-door view.

F.11 Windows connection RBE3-CBUSH-RBE3.

At last the CBUSH connections around both windows, as in F.12 the coordinates orientations are modified in one section to be as the global geometry coordinates direction.

F.12 Orientation general modification to connections.

Conclusion

A rear-door shell mesh geometry assembly was modified as expected to be in a real automotive, several connections were adjusted into the assembly to pre-process the file to be able to perform from it a structural or vibration simulation, arranging the properties, of mass at the handle connection, degrees of freedom, and absorbent coefficients with in the steam lines, perform either bolt connections or spider connection within the assembly areas. The final mesh and connections file are as F.13 representing the file ready to perform a simulation.

F.13 Completed assembly connection.

References

[1] BETA-ANSA documentation, Connections module.