hemker[1] - Mechanics & Materials Faculty Nguyen...

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Unformatted text preview: Mechanics & Materials Faculty Nguyen Hemker Ramesh Sharpe Forces matter ... Microelectromechanical Systems (MEMS) Automotive airbags triggered by MEMS accelerometers MEMS F/S&A device: With Naval Surface Warfare Center LIGA-Ni microsamples: NSWC CAMD LSU 500m m Varying width 50m m Aachen 3 mm Length: ~3 mm Width: 200m wide m Thick: 50~200m thick m Bath: sulfamate CD:: 3~50mA/cm2 15mA/cm2 ~3 mm 50~500m m 300m thick m sulfamate 20mA/cm2 ~3 mm 275m m 120m thick m sulfamate 2& NSWC LIGA Ni samples: ) a P 1500 M ( s s e r t S 1000 Batch 6B : 3mA/cm2 Batch 6A : 6mA/cm2 Batch 5C-5 : 33mA/cm 2 d=0.2m m Batch 5C-9 : 44mA/cm2 500 Batch 1~4 (50mA/cm ) 2 texture: weak <110> 0 0 0.01 0.02 0.03 0.04 40m m Strain d=5m m texture: strong <001> The Mechanics & Materials paradigm Performance - reduced weight - increased temperature Processing Microstructure - crystal structure - grain size - defects - phases - vapor deposition - electrodeposition - cast - wrought Properties - modulus, strength - temperature resistance Length scales: Length scales: 10-12 10-9 10-6 10-3 100 meters 103 106 109 1012 Length scales: telescope microscope 10-12 10-9 10-6 10-3 100 meters 103 106 109 1012 Electron microscopy then and now ... c. 1950 c. 2000 1,000X smaller Whelan, Hirsch, et al. (1957) Balk and Hemker, PMA (2001) Comparisons with a human hair: GE 90 Jet Engine : Material Synthesis Physical vapor deposition (PVD) high-quality thin films Pulsed DC-magnetron sputtering Keep films thin (t < 1 m) High-purity (99.999%) Al target Deposited on high-quality {001} Si wafers Deformation twins in nc-Al: Chen, Ma, Hemker et al., Science 2003 Microsample mechanical testing Linear air bearing Load cell (100 gf max) Translation 5-axis stage motorized stage Picomotor linear actuator Image of mechanical testing setup Schematic of mechanical testing setup Tensile responses of nc-Al films Type I Type II Gianola et al. (2006) Type II tensile behavior of nc-Al ) thin films a 450 P M ( 400 s 350 s e 300 r t 250 S 200 e u 150 r T 100 50 0 0 t = 180 nm davg = 40 nm t = 380 nm davg = 90 nm Microcrystalline Al = 5 x 10-5 s-1 . 5 10 15 True Strain (%) 20 25 Gianola et al. (2006) Is grain growth stress or strain controlled? r 20 e n b o yi m 0 u ctn 0 N nc o 0.4 a ei urt c qF ea 0.2 r r a 30 F e F ra 20 0 e rA 0 r eA 10 n 1 b o e im 0 v tui y 0 nt cN 0.5 c o a 0.2 a in rtelu u Fm c 0 au q 20 re 0.1 a C 40 F r e F ra 0 A e 20 0 rr A e n 1 b o e m iv 0 tiu 0 n t cN 0.5 o 0.2 a a li rt u F c m 0 a u 0.1 0 r a C n F e o i ra 0t A e c 0 r a A 1r e v i t a l u m u C n e u q e r F Batch 2 40 As-Deposited (davg)num = 81 nm ! = 27 nm 50 100 150As-Deposited 200 250 300 350 400 450 Region 1 (davg)area = 99.9 nm Horizontal - Batch 2 ! = 32 nm (davg)num = 124 nm 50 100 150 200 250 ! = 46.5 nm 300 350 400 450 Grain Size (nm) 50 100 150 200 250 Region 1 300 350 400 450 (davg)area = 161 nm 40 60 Region80 2 ! 100 120 140= 160 Horizontal - Batch 2 58.8 nm Grain size (nm) 180 200 61% change from AD (davg)num = 134 nm 50 100 150 200 250 != 300 50 nm 350 400 450 Grain Size (nm) 50 100 150 200 250 Region 2 300 350 400 450 (davg)area = 173 nm 50 100 150 200 Grain size (nm) 200 250 ! =250 nm 300 60.9 350 73% change from AD 50 100 150 300 350 400 450 F Grain Size (nm) Horizontal Batch 2 Combined Cumulative -Distribution Function 1 50 0.5 e 0e v 0 a r A i t a l u m u C AD 100 0.5 1 150 200 Grain size (nm) 2 250 300 350 0 0 50 100 150 200 Grain size (nm) 250 300 350 More grain growth in Region 2 Stress-controlled Micro-compression testing: Slide courtesy of Mike Uchic, AFRL Micro-compression testing: FIB milling Slide courtesy of Mike Uchic, AFRL WEAPONS AND MATERIALS RESEARCH DIRECTORATE Full metal jacket impact of B4C 27.9-mm ARMOR MECHANICS BRANCH 22.0-mm 7.62 mm full metal jacket 0m s 7m s 17m s 19.7-mm 17.3-mm 17.2-mm 17.4-mm 25m s 35m s 45m s 55m s Slide courtesy of W. Gooch, ARL Impact of Club on Golf Ball DRS Hadland Bullet Impact on Soft Objects (Fruit) Failure of a Balloon DRS Hadland NASA Simulation of Asteroid Impact (5km/s) DRS Hadland Impact Crater on the Moon 3 mm Cube Impacting Steel Sheet 2.7 km/s, 10us after impact (DRSH) Bullet Impact on Glass Mechanics of the Cornea Human eye X-section of cornea 0.5 mm (Stroma) 0.25 m X-section of stroma 22 nm ~2 m Adler's Physiology of the Eye Adler's Physiology of the Eye Mechanics of Active Materials heat by laser SMP blood clot remover heat SMP arterial stent ...
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