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Machine Design

Machine design refresher

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jiggly jones
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243 views5 pages

Machine Design

Machine design refresher

Uploaded by

jiggly jones
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF or read online on Scribd
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MDSP REFRESHER COURSE MDSP 2.1 1, Compute the diameter of a solid shaft transmitting 75 Hp at 1800 pm. The nature ofthe load and the type of service is such that the allowable Ss based on pure torsion is* 6000 psi A178” 15/16" B.2 1/16" D.3 1/8" 2. Ahollow circular shaft has an inner radius, rand outer radius R. ‘What percentage of the torque can the shaft carry in comparison with the solid shaft of = 1/2 R? A. 50% B. 74% C.94% D.84% 3. The torsional deformation of a SAE 1040 steel shaft is t0 0.8 in ‘a Iength of % meter. The shear stress is 69 Mpa . Compute the diameter of the shaft in millimeter, Steel modulus of elasticity is 79,300 Mpa or Nimm2 ASI C75 B.30 D.62 4. Shafting up to 3 inches in diameter is usually made from cold rolled steel and the common biggest diameter of cold rolled steel AA % inches B.6 7/8 inches C.6% inches D. 5 inches 5. Compute for the torsional deflection in degrees of a 110 mm ‘iametet, 1b long shaft subjected t a twisting moment of 3 10 (faised to 6) N-mm. The torsional modulus of elasticity is 83 GPa A027 ¢.0.20 B.031 D.024 6. Iron based alloy containing 9-169% chromium ‘A. Mn Hadtield steel C. stainless steel B. chrome-moly steel D. high chrome steel 1. Find the torsional moment (in Newton-mm) developed when the shaft delivers 20 kW at 200 rpm. ‘A085 x 10° B. 10x lo* €.1.20x 10 D.2.10x 10° 8._ A projectile is launched upward from level ground at an angle of 660 deg. with the horizontal. It has a velocity of 45 m/s. Calculate how long will it take before the projectile hits the ground? A 41s C398 B. 58s D.7.94s 9. A small countershaf is 3/4 inch in diameter and has an allowable stress of 8500 psi, Find the horsepower delivered by the shaft at a speed of 125.7 rad/sec. A720 1331 Bld D.14.72 10.A block with a mass of 115 slugs sides down a frictionless wedge ‘with a slope of 40 deg. The wedge is moving horizontally in the ‘opposite direction at a constant velocity of 16 fs. Compute the absolute speed of the block 2 seconds after itis released from rest? A. 21.4 flls C345 Ris. B. 30.91 tus D.12.4 fs 11.The shaft is subjected to a steady load of 36,000 in Ib. at a shear stress of 10,000 psi. Compute the diameter of the said shaft in inches. A178 in C3em B2% in D.76.2mm 12, What is the section modulus of a solid shaft with a diameter of 101.6 mm? ‘A. 102.96 em* C. 209.56 em! B. 205.96 em* D. 205.96 em* 13.The differential of the shear equation is which one of the following? ‘A, load on the beam B. tensile strength of beam . bending moment of the beam MACHINE DESIGN & SHOP PRACTICE D. slope of the elastic curve 14.A steel shaft 1.75 inches in diameter transmits 40 Hp at 1800 rpm, Assuming a modulus of rigidity of 12 x 10® psi, find the torsional deflection of the shaft in degrees per foot length, 0.0073 , 0.0037 1B. 0.0063 D. 0.00013 15. Distance measured perpendicular to the axis between the crest of the thread and the root of its mating thread in a thread assembly of screws A. tolerance class BB. crest truncation . crest clearance D. tolerance limit 16.Perventage of cut on the return stroke of hacksaw blade AQ C1% 8.3% D.0% 17.Compute the nominal shear stress atthe surface, in MPa, for a SO ‘mm diameter shatt that is subjected to a torque of 0.48 kN-m, A. 1695 C2165 B. 19.56 D.25.12 18.4 Vinh diameter shat has single die weighing 75 Io mounted midway between two bearings 20” apart. Find the lowest crit speed in rpm. Neglect the weight of the shaft. Assume that the modulus of elasticity is 30 x 10® psi ‘A. 2038 rpm. ©. 2308 rpm B. 2380 rpm D. 2803 rpm 19. What Hp can a 25.4 mm diameter short shaft transmit at 380 rpm? A.3 Hp 18 Hp B.10Hp D. 7.1 Hp 20. What length of a square key is required for a 4-in diameter shaft transmitting 1000 hp at 1000 rpm? The allowable shear and ‘compressive stresses in the key are 15 ksi and 30 ksi respectively. A211 inches . 2.8 inches B. 3.2 inches D. 4.2 inches 21. Which of the following is not a viscoelastic material? A. Teflon Call of these B. plastic D. metal 22. The material that can cut/wear hardest substance subjected to: A. carbide CC. tungsten B. abrasive D. vanadium 23.A 50-mm diameter shaft is to transmit 12 KW power ata speed of | 500 rpm, determine the mean diameter ofthe pin, under double shear, fora material having safe unit stress of 40 Nimm? A108 mm C. 12.08 mm B. 13.08 mm D. 10.08 mm 24.A 1200 mm cast iron pulley is fastened to 112.5 mm shaft by ‘means of a 28,13 mm square key 175 mm long. The key and shaft have a shearing stress of 14 000 psi. Calculate the force acting at the pulley that will shear the key. ‘A.100151 B.11 050 tb €.12 115 Ib D. 12.105 1b 25.How do you call the process of producing components by compacting and melting of plastic material and continuously forcing it through an orifice hole? A. blowing C. Moulding B Injection moulding D. Extrusion 26.A 75-mm diameter shaft is transmitting 350 KW at 650 rpm. A. flange coupling is used and has 6 bolts, each 18 mm in diameter. Find the required diameter ofthe bolts circle based on an average shearing stress of 27.5 MPa, A.245 mm ©, 254mm 8.492 mm D. 425 mm. MDSP REFRESHER COURSE 27. Itis ideal for maximum quietness in sprockets drive operation to choose or more teeth Am 27 B.S. D.21 28.1f the angular deformation of a solid shaft should not to exceed 1° in a length of 1.8 mand the allowable shearing stress is 83 MPa, what is the diameter of the shaft? Assume that the shaft material has G = 77 x 10° kPa. A. 222.34 mm B. 23.42em C. 234.22 mm D. 24.22em 29.A vertically loaded beam, fixed at one end and simply supported atthe other is indeterminate to what degree? A. First . Second B. Third D. Fourth 30,A. 15/16 ~ in wide key has a depth of 5/8 mn. 1s 12 inches long ‘and is to be used on # 200 hp, 1160 rpm, squirrel -cage induction motor. The shaft diameter is 3 7/8 inches. The maximum running, torque is 200% of the full-load torque. Compute for the force A. 11,2171 ©. 27,111 1b B. 57,211 Ib D. 72,101 Ib 31. Itis rigid piece which serves to transmit force from a piece another piece or fo cause/ control motion A. follower . cam motion B. crank D. link 32,Aside from oxygen, what is the other commonly used gas in gas welding? A. hydrogen C.LPG B. argon D. Acetylene 33.A 15/16 ~ in wide key has a depth of $/8 in, It is 12 inches long ‘and is to be used on a 200 hp, 1160 rpm, squirrel -cage induction motor. The shaft diameter is 3 7/8 inches. The maximum running torque is 200% of the full-loed torque. What is the maximum, torque? A. 17,330 €. 73,210 ina B. 73.412, D. 21,733 in-lb 34,Determine the shear stress at the inside surface of a hollow circular shaft where the torque is 8000 ft-lb of inside and outside diameters are 2 in and 4 inches respectively. ‘A.41 Mpa C55 ksi B.28.1 MPa D.12.4 ksi 35.A turbine developing 15,000 Hp turns the shaft at 300 rpm. The ‘propeller attached to this shaft develops a thrust of 150,000 Ib. A hollow steel shaft having an outside diameter of 14 in. is to be used. What is the percentage savings in weight? Note: Ss = 7500 Psi A.373% C455 % BMS% D.32.7% 36.1f the following solid shaft diameters, which is the smallest that ‘ean be used forthe rotor ofa 6 hp motor operating at 3500 rpm, if ‘the maximum shear stress for the shaft is 8500 psi? A.SII6 in C.Lin B.38in D.4in 37.In general, what are the effects of cold-working a metal? ‘A. increase strength and ductility B. decreased strength and ductility C. increased strength, decreased ductility D. decreased strength, increased ductility 38. The effective length ofa cantilever spring of uniform rectangular ‘cross-section is 20 inches. AC its free end, it carries a load of 720 Ibs and caused a 1.2 inch deflection. Calculate the thickness of the spring given that the material’s allowable stress is 70 ‘4.0519 in, 0.353 in, 1.0420 in 0.201 in, 39.A flange bolt coupling consists of eight steel 20-mm diameter bolts spaced evenly around a bolt circle 300 mm in diameter. MACHINE DESIGN & SHOP PRACTICE Determine the torque capacity of the coupling if the allowable shearing stress in the bolls is 40 MN/m? A. LST kN-m €.5.21 Nem B. 15.1 kN-m D.10.51 kN-m 40.Find the diameter of a steel lineshaft to tansmit 10 Hp at 150 revolutions per minute with a torsional deflection not exceeding. 0.08 degree per foot of length. A. 352i B. 235 in, ©. 3.25 in D. 253 in, 41. Cast iron flywheels are commonly designed with factor of safety of A.10t0 13 B. 10 to 12 C1010 14 D.8013 42. The undersea research vehicle Alvin has a spherical pressure boll 1m in radius and shell thickness of 30 mm. The pressure hull is steel having a yield point of 700 MPa. Compute the depth of submergence that would set up the yield point stress in the spherical shell, Give: Sea Water specific weight is 10.07 kNim* ‘A. 5040 m C.4170m B.1240m D.1470m 43, Cast iron pulleys, 4 in, and 20 in, in diameters, are to transmit 3 bp at 1200 rpm of the smaller pulley, through a single ply oak- tanned leather bell, Calculate the centrifugal stress if the center to center distance is 10 f Note: for leather belt f 0.30, density is 0.035 Ibitt A.5.75 psi €.23.6 psi B. 32.5 psi D.1.45 psi 44.A cyclist on a circular track of radius 800 fis travelling at 27 fs, is speed in the tangential direction increases at the rate of 3 fs? What is the total cyclist’ acceleration ASA fve C3. fst Banus D.091 tus? 45. What horsepower would be transmitted by a short shall, 2 inches in diameter carrying two pulleys closed to the bearings, ifthe shaft makes 300 revolutions per minute. A. 36hp C63 hp B. 4S hp D. Shp 46.4 flange bolt coupling is used fo connect a solid shaft 90 mm in diameter to a hollow shaft 100 mm in outside diameter and 90 mm, in inside diameter. If the allowable shearing stress in the shafts, and the bolts is 60 MN/m?, how many 10-mm-

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