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3. (a) Define Friction. Schematically illustrate and explain the Adhesion and Abrasion theories of friction. [10 marks] (b) How is surface roughness measured? [4 marks) (c) Ultrasonic inspection is used to see beneath the surface of a part and to inspect internal features. How is this process applied and what information will it generate? [6 marks) Total marks: 20
Formula sheet a. Casting Solidification time=0 TE Volume Area Bernoulli's Theorem ht+ P11 + =ht P2 + 12 pg 29 pg Mass continuity equation : Q = A v; = AzV2 = Area x velocity Reynold Number: Re = vDp Flow speed x Diamater x Fluid Density Dynamic viscosity of the fluid H b. Rolling Power per roll πFKN 60 where N(rpm) Roll force, approximate (frictionless condition) F = Lwo', Roll force, approximate (frictional condition) F = Lwo" (1+ ul 2h Contact Length L = VRAM Average flow stress in plain strain of material in the roll gap: 0; = 1.15 KE Average flow stress, og n+1 True strain, E = In c. Sheet metal forming Maximum punch force in shearing Fmax = 0.7SUTEL Average normal anisotropy ratio for rolled sheet R = Ro + 2R9s + Ryo D. Limited Drawing ratio, LDR Dp Springback estimation, approximate R = 4 RI ( ) - (2) - +1 Et
2R (284) + 1 af Sprinback factor, K = αι +1 = 2R () + 1 d. Generated Heat in resistance welding H = 12Rt Heat for melting certain volume of material, H = uvm