EBW tooling for PETSFEM

Riku Raatikainen 2.5.2011

Motivation for FE-analysis:

-Demonstrating the structural behavior of the PETS under compressive force in a workbench for welding

- Large value of force could lead into stability problems. Appropriate force range is needed for tooling without significant deformation

Geometry

Cross Section View

PETS Structure

- Copper Alloy (yellow)- Structural Steel (grey)

Geometry

Gaps (50 µm) for Welding

Simplified Geometry

• Simplified geometry was created including the outer shell and inner solid structure without damping material

• Critical connecting surfaces (load carrying surfaces) remain the same

Outer Shell

Inner Solid

FE-Analysis

Assumptions and restrictions:

• Maximum total deformation of 50 µm were allowed (transversal < 10-20 µm)

• Friction factor between Copper-Copper surfaces roughly ~ 1.0

• PETS under axial loading + the effect of gravity

• Effect of rotational velocity was neglected since its small value (~ 0.004 rad/s)

Mesh/Loads/Boundary Conditions

Fixed Surface

Axial Loading (Screw)

Gravity

Radial fixed, Axial & Tangential Free

Approximately 34 000 elements

Fully frictional contacts were used

Results

Total deformation under 5 kN of axial force ~ 8 µm(small transversal deformation)

Total deformation under 50 kN of axial force ~ 70 µm(transversal deformation > 10 µm)

Results-Extra

Illustration of steel shell losing its stability if too large force value is applied

Conclusion

• Axial forces of 500-1000 kg (or more) can be achieved easily by tooling workbench, which should ensure the reliable tooling for the PETS welding. Large forces (several tons) will lead into instability.

• Exact forces can adjusted furthermore in machining

• Parts to be welded could be attached into the structure by using spot welding before actual welding > Even more reliable and accurate alignment

• For more detailed analysis the roughness of the contact surfaces should be studied more closely