Gravity load on SAS – comparison between real and mock-up April 13 th, 2016

1.Introduction 2.Simulation 3.Conclusions

1. Introduction Super Accelerating Structure (SAS) of CLIC module ModuleAS SAS

1. Introduction Accelerating Structure (AS) of CLIC module Complete model of SAS Mock-up

1. Introduction Support system V-supports fixed to the girder Setup as planned for module assembly T1:

1. Introduction Support system Modelling of the V-supports: principle Supports are made fixed (in real case sliding is allowed but are ”fixed” by clamping) AS V-supports Tangential contact-> Line supports AS

1. Introduction Modelling of gravity load using Finite Element Method (FEM) Aim of the FEM simulation is to model the macroscopic deformations and stresses of the SAS structure due to its own weight (gravity load). Comparison between real structure and mock-up is important because next module assembly T1 will consist of real AS instead of mock-ups and the support system could still be modified if needed. The modelling is done using ANSYS 16.2 The FEM simulation of includes: – Static structural analysis – Isotropic elastic material (work-hardened copper with high Yield strength 280 MPa: later we will see that this is not critical property) – Bonded contacts between parts – Gravity load

1.Introduction 2.Simulation 3.Conclusions

2. Simulation SAS Mock-up: model Some geometries suppressed: bellows, flanges, pipes,... Load and boundary conditions: gravity, fixed supports at the V-support lines Mesh: 0.7 million nodes, 0.4 million elements

2. Simulation SAS Mock-up: results Vertical deformation [m]

2. Simulation SAS Mock-up: results Vertical deformation [m]: labeled points are selected inside the beam cavity Negative is down

2. Simulation SAS Mock-up: results Total equivalent stress [Pa] Global max (on the supports because they are fixed…) stays below 2 MPa

2. Simulation SAS Real: model Some geometries suppressed: bellows, flanges, pipes,... Load and boundary conditions: gravity, fixed supports at the V-support lines Mesh: 1.8 million nodes, 1 million elements

2. Simulation SAS Real: results Vertical deformation [m]

2. Simulation SAS Real: results Vertical deformation [m]: labeled points are selected inside the beam cavity Positive is down

2. Simulation SAS Real: results Total equivalent stress [Pa] Stress is not critical -> do not have to include plasticity In the middle the local max stays at ~ 1 MPa

2. Simulation SAS Mock-up vs. Real: results Vertical deformation [µm] along the beam cavity

2. Simulation Extra: SAS Real with “brazing-mixed” regions in the middle In current SAS, the two bonded disc stacks are connected to each other by brazing. Silver is used as brazing material Small regions around the brazed joints get mixed with silver: mixed alloy has different mechanical properties than pure copper. This might change structural properties Currently there are no possibility to model brazed joint directly in ANSYS. Disc stack

2. Simulation Extra: SAS Real with “brazing-mixed” regions in the middle Model the effect of brazed contact by setting thin slice (~0.5 mm) of the body as silver. The thin slice is connected to surroundings by basic bonded contacts. Note: Using silver instead of mixed copper-silver alloy

2. Simulation Extra: SAS Real with “brazing-mixed” regions in the middle Vertical deformation [m]: labeled points are selected inside the beam cavity (floor) Positive is down No notable difference to the previous result

1.Introduction 2.Simulation 3.Conclusions

Effect of gravity load on real SAS structure and mock-up was simulated with FEM. V-supports were modelled as fixed line supports with approximately the setup seen in T1. Deformations on the mock-up were near to zero; in real SAS the maximum deformation along the beam line was 1 µm. Equivalent stress in the middle region of real SAS remained around 1 MPa -> no plasticity expected. Brazed regions in real SAS were modelled with simplistic approach changing the material of brazed region. There were no notable difference to the previous case.