Stress linearization Analysis performed on the submodel with
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 -> Rp 0. 2 = 70 MPa Standard FEM strength assessment According to EN 13445 -3: 2002 -> f = Rp 0. 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 CRAB cavities meeting Luca Dassa – 23/03/2015 1/9
CRAB cavities meeting FEM (2) 1. 5 f = 70 MPa Path 1 Luca Dassa – 23/03/2015 2/9
Path 2 CRAB cavities meeting FEM (3) 1. 5 f = 70 MPa Luca Dassa – 23/03/2015 3/9
Path 3 FEM (4) 1. 5 f = 70 MPa CRAB cavities meeting Luca Dassa – 23/03/2015 4/9
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“ ? CRAB cavities meeting Luca Dassa – 23/03/2015 5/9
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)) M 6 x 1 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. CRAB cavities meeting Luca Dassa – 23/03/2015 6/9
Washers: another possibility? CRAB cavities meeting Luca Dassa – 23/03/2015 7/9
CRAB cavities meeting Test on bolts Tests on bolts: works in progress Luca Dassa – 23/03/2015 8/9
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 CRAB cavities meeting Luca Dassa – 23/03/2015 9/9
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