MesoScale High Cycle Fatigue Tests of Irradiation Ti6

New mushroom meso-fatigue design • Low stress concentration • High inertia to increase stress

Design one Design two Ф 3. 4 mm R 0. 8 mm R 0.

Resonant frequency (Hz) of two thickness Thickness Design one R 0. 8 mm Design

Layout four types specimens in the primary foil Line 1 Design one Line 2

Micro-laser machining of trial foil: four types, 115 specimens

Step increase fatigue tests @ 106 cycles Failure vibration amplitude Thickness Design one Design

Based on vibration experiments, final dimension is determined Ф 3. 4 mm R 9.

Foil one: thickness measurements 230 242 239 228 247 250 252 250 249 260

Foil two: thickness measurements 253 257 262 252 257 256 255 260 253 257

New layout for irridiation foils with final design Line 1 Line 2 Line 3

Status (C Densham) • 2 test foils lapped to correct thickness • Laser cutting

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Meso-Scale High Cycle Fatigue Tests of Irradiation Ti-6 Al-4 V Jicheng Gong & Angus J Wilkinson Micromechanics Group, Oxford University 14 th Nov 2016

New mushroom meso-fatigue design • Low stress concentration • High inertia to increase stress • Lower resonant frequency to compensate the influence of increased thickness • Compact to layout more specimens against the limited size of a foil • Work with new holders

Tensile stress along axis Tresca stress

Design one Design two Ф 3. 4 mm R 0. 8 mm R 0. 9 mm Design four Design three R 1. 0 mm R 1. 1 mm

Resonant frequency (Hz) of two thickness Thickness Design one R 0. 8 mm Design two R 0. 9 mm Design three R 1. 0 mm Design four R 1. 1 mm 250 um 33805 28649 24595 21347 272 um 36507 30952 26582 23079 Elastic modulus = 114 GPa; Density = 4450 Kg/m 3; Poisson’s ratio= 0. 34

Layout four types specimens in the primary foil Line 1 Design one Line 2 Line 3 Line 4 Design two Line 5 Line 6 Line 7 Design three Line 8 Line 9 Design four Line 10 Line 11

Micro-laser machining of trial foil: four types, 115 specimens

Step increase fatigue tests @ 106 cycles Failure vibration amplitude Thickness Design one Design two Design three Design four ~ 260 um 10 um 20 um 30 um 40 um

Based on vibration experiments, final dimension is determined Ф 3. 4 mm R 9. 5 mm Resonant frequency: 28477 Hz Note the width of the cantilever was also modified to compensate the width of laser beam

Foil one: thickness measurements 230 242 239 228 247 250 252 250 249 260 252 257 255 256 257 256 252 258 249 258 260 252 246

Foil two: thickness measurements 253 257 262 252 257 256 255 260 253 257 259 261 258 253 257 259 257 258 260 256 243

New layout for irridiation foils with final design Line 1 Line 2 Line 3 Line 4 Line 5 Line 6 Line 7 Line 8 Line 9 Line 10 Line 11

Status (C Densham) • 2 test foils lapped to correct thickness • Laser cutting proven, experimental foil cutting imminent • Vibration test procedure verified • Culham Materials Research Facility being commisioned – will be 1 st active samples received