1. Luca Dassa – 23/03/2015 1 / 9 CRAB cavities meeting Stress linearization Analysis performed on the sub-model (with previous remarks) I think that in any case the main considerations are the same FEM (1) From test performed on material EDMS 1493400 -> Rp0.2 = 70 MPa Standard FEM strength assessment According to EN 13445-3:2002 -> f = Rp0.2/1.5 = 47 MPa Design by analysis – method based on stress categories According to EN 13445-3:2002 -> 1.5*f = 70 Mpa What about bending stress? Primary or secondary? I assume that they are primary stress

2. Luca Dassa – 23/03/2015 2 / 9 CRAB cavities meeting FEM (2) Path 1 1.5 f = 70 MPa

3. Luca Dassa – 23/03/2015 3 / 9 CRAB cavities meeting FEM (3) Path 2 1.5 f = 70 MPa

4. Luca Dassa – 23/03/2015 4 / 9 CRAB cavities meeting FEM (4)Path 3 1.5 f = 70 MPa

5. Luca Dassa – 23/03/2015 5 / 9 CRAB cavities meeting FEM (5) Conclusions: Standard FEM strength assessment: NOT VERIFIED Design by analysis – method based on stress categories: NOT VERIFIED Design by analysis – Direct Route -> material constitutive law: linear-elastic ideal-plastic -> very complicate strength assessment Should we go with strength assessment according to “Design by analysis – Direct Route“ ?

6. Luca Dassa – 23/03/2015 6 / 9 CRAB cavities meeting Galling Galling on bolts It seems that galling could be a problem, above all with super-clean bolts Coating on Ti bolt never requested at CERN (phone call with M. Malabaila) threaded inserts? (available in stainless steel and Nitronic 60 (Jeweka)) M6x1 L=9 mm available A possible solution that we´ve researched only at present, is hardening the Titanium Grade 5 surface of the fasteners by making use of Ion Implantation. Kolsterizing this material is not possible, but the results I´ve seen on paper from Ion Implantation look promising. Advantage of this message is, that it´s not a coating that can come off and produce particles.

7. Luca Dassa – 23/03/2015 7 / 9 CRAB cavities meeting Washers: another possibility? Washers

8. Luca Dassa – 23/03/2015 8 / 9 CRAB cavities meeting Tests on bolts: works in progress Test on bolts

9. Luca Dassa – 23/03/2015 9 / 9 CRAB cavities meeting HSE meeting Meeting with HSE (C. Arregui Rementeria) on 20/03/2015: What has been stated by HSE in the past is not anymore valid Voltage in the cavity is not a reason to be out of the scope of PED directive, as well the exotic materials The equipment should be CE marked! Since we are dealing with category 1 equipment, an exemption could be discussed, but it shall be supported by valid reasons