EBW tooling for PETS FEM Riku Raatikainen

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 < 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 (~ rad/s)

Mesh/Loads/Boundary Conditions Fixed Surface Axial Loading (Screw) Gravity Radial fixed, Axial & Tangential Free Approximately 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 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