MATERIAL CRITERIA STUDY for ESRF thermal absorbers

Transcription

1 ESLS2003 ESRF, Grenoble, France November 2003 MATERIAL CRITERIA STUDY for ESRF thermal absorbers L Zhang, JC Biasci, B Plan European Synchrotron Radiation Facility

2 Outline Introduction ESRF storage ring absorbers Design review Finite Element Analysis (FEA) updating Tests and experiences with absorbers Design criteria for thermal absorbers Present Extended based on linear model R&D for Advanced Conclusion Page 2 / 15

3 Introduction E-beam current upgrading from 200 to 300, 500 ma at the ESRF power increase by 50%, 150% Review of the ESRF thermal absorbers Design review FEA updating Safety evaluation Design criteria Commonly used (σ VM max < σ yield ) safe but too conservative More appropriate design criteria for thermal absorbers Tests with ID beam, material limits Page 3 / 15

4 ESRF storage ring absorbers design 3 major absorbers: distributed, crotch, flat absorbers + some special absorbers distributed absorber flat absorber stainless steel vacuum vessel X-ray OFHC copper X-ray OFHC copper water cooling channel Stainless steel water cooling box crotch absorber special crotch absorber Glidcop OFHC copper back plate OFHC copper cooling tubes X-ray Glidcop OFHC copper X-ray Page 4 / 15

5 FEM Elastic assumption on the thermal deformation If the computed stress > elastic limit of the material, the computed stress is only an apparent stress related to the thermal strain Distributed absorber Flat absorber W/mm 2 stainless steel stainless steel Crotch absorber OFHC copper OFHC copper W/mm 2 Glidcop C OFHC copper Page 5 / 15

6 Graal absorber (safely operated during 5 years) Glidcop design Installed in summer 1994 and replaced in December 1999 by a common crotch absorber FEA results : T max =587 C Tw max =211 C (local) σ VM max=828 MPa (local) Destructive analysis results Scanning Electron Microscope Material structure analysis no cracks, no degradation Page 6 / 15

7 Special crotch absorber OFHC copper design C3/d_strm-K2 Replaced in Aug by a Glidcop version FEA results : T max =261 C Tw max =83 C σ VM max =414 MPa No cracks on the trace marked by X- ray power were observed under optical microscope Page 7 / 15

8 Crotch absorber - tests with Undulator beam power (2001) OFHC copper crotch absorber tested with 3 segments of undulator Aim of the tests : FEA validation Temperature and stress limits FEM with undulator beam power No particular behavior (such as sudden temperature and/or pressure increases) was observed during tests with 1 segment of ID ~1 month (σ VM max=428 MPa) with 2 segments of ID 2~3 hours (σ VM max=726 MPa) Temperature distribution Page 8 / 15

9 Summary material : Glidcop (+OFHC) type identification σ P l P a P total T max Tw max σ VM max comments (material) mm W/mm W/mm 2 W C C MPa crotch CV OK graal C7/CV06 (old) safe ~ 5 yrs material : OFHC tested crotch 1 U34/ safe ~1 month with IDs 2 U34/ mm safe 2~3 hours special crotch C3/d_strm-K OK, upgraded CV15A OK distributed C3/d_strm-K OK flat CV OK cooling water temperature T water = 22 C Page 9 / 15

10 Design criteria for thermal absorbers Present Commonly used criteria in the thermal absorber design : maximum temperature of the absorber T max < T melt maximum cooling wall temperature Tw max < T water-boiling maximum Von Mises stress in the absorber σ VM max < S yield, S fatigue, S ultimate tensile Data of yield and ultimate tensile strengths Temperature, thermal treatment, composition, shape S yield = 45 and S ultimate tensile = 210 MPa for annealed OFHC copper S yield = 331 and S ultimate tensile = 413 MPa for Glidcop At the ESRF : Glidcop : σ VM max <S yield (cold)+s yield (hot)=430 MPa for T max =400 C 400 MPa for T max =500 C OFHC copper : σ VM max < 295 MPa, P l < 20 W/mm for flat and distributed absorbers At the APS T max < 300 C for glidcop T max < 150 C for OFHC copper Page 10 / 15

11 Design criteria extension linear model X-ray heat load induced thermal stress in the copper absorbers concentrated in very local area near surface mainly compressive eventual plastic deformation in very small region is confined by the large elastic part and does not propagate thermal stress is much less critical than mechanical stress Proposed design criteria for copper absorbers : σ VM max < 2*S ultimate 400 MPa for OFHC copper σ VM max < 2*S ultimate 850 MPa for Glidcop σ VM max : calculated maximum Von Mises stress with the elastic assumption Based on the linear model and for easy use (pragmatic) Ultimate limit unknown Different from conventional criteria (σ VM max <S yield, S fatigue,s ultimate tensile ) non-linear model with elastoplastic and/or creep effects + tests Page 11 / 15

12 Design criteria R&D Tests of copper thermal absorbers Heat load test with a dedicated in-house test beamline (ID6) OFHC copper or Glidcop Samples (Φ20x5) Crotch absorbers Heat load cycling (non-destructive, and eventually destructive) X-ray diffraction tests (ID15) Residual strain distribution Metallurgic tests (external collaboration) Advanced modeling (FEA) Elastoplastic effect Creep effect Heat load cycling (transient analysis) Advanced Material data, software are needed Validation of advanced FEA Establishing new design criteria Page 12 / 15

13 Design criteria R&D Photon beam absorber Advanced FEA (elastoplastic & creep) Heat load Test with ID6 Undulator beamline FEA (linear) non destructive non destructive X-ray diffraction test (ID15) Residual strain (stress) comparison FEA model validation destructive Mechanical criteria (classic) σ FEA-linear > σ Y, or σ U absorber OK modify criteria Classic mechanical criteria σ FEA-Elastoplastic < σ Y, or σ U Thermal Mechanical criteria (new) nσ U > σ FEA-linear, (n>1) n=? to be defined Page 13 / 15

14 Design criteria R&D Heat load test in ID6 beamline sample and sample holder Water cooled crotch absorber (replaced part) Sample (OFHC copper or Glidcop) Page 14 / 15

15 Conclusion X-ray heat load induced stress in the copper absorbers Compressive Concentrated in a small region near the surface The conventional design criterion (σ VM max > S yield ): too conservative Proposed design criteria for thermal absorbers based on linear model (only elastic deformation): σ VM max < 2*S ultimate = 400 MPa for OFHC copper σ VM max < 2*S ultimate = 850 MPa for Glidcop R&D project at the ESRF Experimental tests (heat load, X-ray diffraction, ) Advanced FEA (elastoplastic, creep, heat load cycling) Design criteria for thermal absorbers Page 15 / 15