HQ test at CERN: strain and stress measurements H. Bajas, A. Chiuchiolo 02/09/2012 Hi-Lumi special session on HQ test results

OUTLINE Summary of the HQ01-e mechanics during its service life Detail analysis of the stress/strain behaviour during operation

OUTLINE Summary of the HQ01-e mechanics during its service life Detail analysis of the stress/strain behaviour during operation

H. BAJAS | Hi-Lumi special session on HQ test results Summary of the HQ01-e mechanics during its service life STRESS history Good agreement with measurement from [Ferracin 2012] and coherence from expectation. Low spread from SGs of different positions. 02/09/2012 H. BAJAS | Hi-Lumi special session on HQ test results

H. BAJAS | Hi-Lumi special session on HQ test results Summary of the HQ01-e mechanics during its service life STRESS at quenches Good stability of the stresses for SHELL and RODS for the 55 quenches. Critical positive stress measurements at the POLES. 02/09/2012 H. BAJAS | Hi-Lumi special session on HQ test results

OUTLINE Summary of the HQ01-e mechanics during its service life Detail analysis of the stress/strain behaviour during operation

H. BAJAS | Hi-Lumi special session on HQ test results Detail analysis of the stress/strain behaviour during operation COOLDOWN: Detail STRAIN analysis of shell and rods Rods axial Rods axial 1262 mɛ 1277 mɛ Cool-down Warm-up Temperature range: 291K - 1.9K 02/09/2012 H. BAJAS | Hi-Lumi special session on HQ test results

H. BAJAS | Hi-Lumi special session on HQ test results Detail analysis of the stress/strain behaviour during operation COOLDOWN: Detail STRAIN analysis of shell and rods Shell axial Warm-up Cool-down 511 mɛ 534 mɛ Shell azimuthal Warm-up Cool-down 990 mɛ 1018 mɛ 02/09/2012 H. BAJAS | Hi-Lumi special session on HQ test results

H. BAJAS | Hi-Lumi special session on HQ test results Detail analysis of the stress/strain behaviour during operation COOLDOWN: Detail STRAIN analysis of the poles Pole axial 230 mɛ 189 mɛ Cool-down Warm-up Pole azimuthal 608 mɛ 639 mɛ Cool-down Warm-up 02/09/2012 H. BAJAS | Hi-Lumi special session on HQ test results

Computation of the stress from strains in both directions Detail analysis of the stress/strain behaviour during operation STRESS to STRAIN computation Computation of the stress from strains in both directions assuming friction-less and elastic behaviour: Shell and Pole Rods E = 79 GPa and n = 0.34 for Aluminum (Shell and Rods) E = 130 GPa and n = 0.3 for Titanium (Poles) 02/09/2012 H. BAJAS | Hi-Lumi special session on HQ test results

H. BAJAS | Hi-Lumi special session on HQ test results Detail analysis of the stress/strain behaviour during operation POWERING: Detail STRESS analysis of shell and rods 93 ± 15 MPa 184 ± 11 MPa Right Right Bottom Bottom Top Top Left Left 163 ± 4 MPa Small spread with different locations for shell azimuthal more for the axial direction. Same slope for shell and rods: 0.013 [MPa/kA2] Relaxation with cycles (first vs. last): SHELL axial: Slight (<13%) SHELL azimuthal: Marginal (<3%) RODS axial: Marginal (<3%) A, B, D C 02/09/2012 H. BAJAS | Hi-Lumi special session on HQ test results

H. BAJAS | Hi-Lumi special session on HQ test results Detail analysis of the stress/strain behaviour during operation POWERING: Detail STRAIN analysis of the poles C8 C7 C9 C9 C8 C7 C5 C5 Azimuthal: Different offsets but linear behaviour Same slope but for coil 7 Flattening for the 4 coils with current (> 15 kA) and with number of quenches Marginal relaxation with quenches ( < 3 % ) Axial: Highly non linear Significant relaxation with quenches ( > 50 % in C7&5, >10% in C9) C7 C5 C8 02/09/2012 H. BAJAS | Hi-Lumi special session on HQ test results

H. BAJAS | Hi-Lumi special session on HQ test results Detail analysis of the stress/strain behaviour during operation POWERING: STRESS analysis of the poles C7 & 8 C7 & 8 C5 C5 Linear behaviour (slope: 0.75 MPa/kA2) for azimuthal (0.21 for axial). Azimuthal stress beyond 0 Mpa shows proof of cable/pole de-bounding at high current > 15 kA. Relaxation with quenches: azimuthal: Marginal ( < 3 %) axial: Significant ( > 20 %) C7 C5 & 8 02/09/2012 H. BAJAS | Hi-Lumi special session on HQ test results

H. BAJAS | Hi-Lumi special session on HQ test results Detail analysis of the stress/strain behaviour during operation Detail axial STRAIN analysis of the poles First run @ 1.9 K Different behaviour between the three Coils (5, 7, 8) due to Lorentz force loading: C5 & C7 are compressed. C8 extends. Ratcheting and non-linearity evidences: Gradual sliding of the cable Plasticity 02/09/2012 H. BAJAS | Hi-Lumi special session on HQ test results

H. BAJAS | Hi-Lumi special session on HQ test results Detail analysis of the stress/strain behaviour during operation Detail axial STRAIN analysis of the poles Second run @ 1.9 K The coil 7 is completely unloaded in the axial direction at the end of the test. The coil 8 is more stable The warmup/cooldown brings it back to its initial position. 02/09/2012 H. BAJAS | Hi-Lumi special session on HQ test results

H. BAJAS | Hi-Lumi special session on HQ test results conclusion Good control of the magnet structure mechanics (shell, rods, pole) with agreement between with FEM computation, LBNL 1st run and CERN 2nd and 3rd run. Presence of offset (physical or not ) but same slope. Good stability with warmup-cool-down and number of quenches Signs of cable/pole de-bounding (pole azimuthal stress beyon 0 MPa) at current greater than 15 kA with effect of the number of quenches. Signs of sliding and/or plasticity of the cable (strong relaxation of the pole axial strain) Can we link quenched coils (mostly 7&8) with the strain state of the pole? What is the actual strain of the cable around its pole (Ic(B,T,e))? 02/09/2012 H. BAJAS | Hi-Lumi special session on HQ test results 16