1. Status of DCH Mechanical Structure 13 Dec 2011

2. S. Lauciani2 Summary Proposal for a mechanical structure of DCH Stringing strategy and analysis of deformations Buckling analysis on DCH

3. 13 Dec 2011 S. Lauciani3 Proposal of a mechanical structure: General layout External load bearing structure Thin inner cylinder Endplates fixed only on outer rim Homogeneus distribution of material in axial and angular direction Two halves shell is a preferred solution with respect to a single cylindrical one. It is less expensive, uses less radial space and it is easier to build. Inner rim is free to move in axial direction

4. 13 Dec 2011 S. Lauciani4 Endplate: materials and geometry Ex = 130 GPa n xy = 0.3 Gxy = 4.5 GPa Ey = 4.6 GPa n xz = 0.3 Gxz = 4.5 GPa Ez = 4.6 GPa n zy = 0.25Gzy = 4.5 GPa CF properties* Ply#Lamina TypeThickness(mm)Angle (deg) 1Graphite/Epoxy0.2500 2Graphite/Epoxy0.25090 3Graphite/Epoxy0.25090 4Graphite/Epoxy0.2500 Ply#Lamina TypeThickness(mm)Angle (deg) 1Graphite/Epoxy0.25090 2Graphite/Epoxy0.25090 3Graphite/Epoxy0.25090 4Graphite/Epoxy0.25090 8 x10 x Ply#Lamina TypeThickness(mm)Angle (deg) 1Graphite/Epoxy0.25090 2Graphite/Epoxy0.25090 3Graphite/Epoxy0.25090 4Graphite/Epoxy0.25090 20 x EndplatesInner stiffening ring Outer stiffening ring To consider the holes effect, material properties are downgraded by a factor of 0.7 *Taken from datasheets, may vary 10-20 %

5. 13 Dec 2011 S. Lauciani5 Wires: Materials and load Wire typeMatr (mm)N° WiresSag. (mm) FieldAluminium0.04246600.2 SenseMolybdenum (AU coated)0.01258360.2 GuardAluminium0.0480560.2 Minor changes in wire layout, inner and outer diameter have not an important effect on results Considering a maximum wire’s length of 2700mm and endplate curvature the nominal load is 15677 N Endplate curvature and thickness have a great influence on deformations

6. 13 Dec 2011 S. Lauciani6 FEM model for stringing process Initial Load (N) Force 01767 Force 02699 Force 03967 Force 04820 Force 05470 Force 06467 Force 07682 Force 08659 Force 09578 Force 10790 Force 11754 Force 12878 Force 13687 Force 14866 Force 15964 Force 16755 Force 17952 Force 181034 Force 19826 Force 201052 Endplate is divided in 20 circular areas. Total load is applied in 20 steps For every step displacements are calculated Every load is decreased according to material, length and deformation of every wire

7. 13 Dec 2011 S. Lauciani7 Final displacement Initial Load (N)Final Load (N) Force 01767670 Force 02699619 Force 03967864 Force 04820743 Force 05470429 Force 06467427 Force 07682623 Force 08659604 Force 09578531 Force 10790727 Force 11754697 Force 12878817 Force 13687644 Force 14866818 Force 15964921 Force 16755732 Force 17952933 Force 1810341026 Force 19826825 Force 201052 Max displacement: 0.31mm Total nominal load: 15677 N Total real load: 14711 N

8. 13 Dec 2011 S. Lauciani8 Stringing: Final sagitta For a fixed displacement sense wires have a greater sagitta than field wires. Molybdenum is more rigid (E_mo=320 e3 Mpa E_al=68.9 e3 Mpa) On the first layer act all the stringing process, so the difference is greater The first layers “feel” all the stringing process, so the difference in sagitta is larger Max. Sagitta difference : 0.026mm Nominal sagitta This plot takes into account a further displacement due to the cylindrical shell deformation, about 0.07mm

9. Buckling: Shell material Ply#Lamina TypeThickness(mm)Angle (deg) 1Graphite/Epoxy0.2500 2Graphite/Epoxy0.25090 3Graphite/Epoxy0.25090 4Graphite/Epoxy0.2500 5Honeycomb60 6Graphite/Epoxy0.2500 7Graphite/Epoxy0.25090 8Graphite/Epoxy0.25090 9Graphite/Epoxy0.2500 13 Dec 2011 S. Lauciani9 Cylindrical shell. Thickness 8mm Ex = 130 GPa n xy = 0.3 Gxy = 4.5 GPa Ey = 4.6 GPa n xz = 0.3 Gxz = 4.5 GPa Ez = 4.6 GPa n zy = 0.25Gzy = 4.5 GPa Ex = 138 MPa n xy = 0.02 Gxy = 1 MPa Ey = 3 MPa n xz = 0.02 Gxz = 45 MPa Ez = 3 Mpa n zy = 0.02Gzy = 24 MPa Honeycomb properties CF properties 1mm CF 6mm HC 1mm CF

10. 13 Dec 2011 S. Lauciani10 N°Buckling Load (N) 10.32856E+06 20.32863E+06 30.32910E+06 40.36709E+06 50.40102E+06 6 70.40103E+06 8 90.45618E+06 100.45618E+06 Buckling occurs only on endplates. Using HC allow to avoid instability problem on cylindrical shell and to use less material First instability load: 328560 N 20 times higher than wire load Buckling: Analysis

11. Conclusions and plans Inner load bearing cylinder is not needed DCH can be strung without overtensioning wires CF laminates are optimized to reduce displacement The numbers used for the DCH inner radius, length and thickness of all elements are close to final, but we will check for updates. These updates are expected not to cause important changes on the conclusions Realize some test due to uncertainty on material properties Understand effect of feed-through holes with tests Understand how DCH is supported 13 Dec 2011 S. Lauciani11