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Machine Design Problems: A Comprehensive Guide for Engineering Students - Prof. Mendoza, Summaries of Thermodynamics

Adamson University (AU)Thermodynamics
Prof. Shaun Mendoza

Thermodynamics Notes For you to Study

Typology: Summaries

2022/2023

Uploaded on 12/13/2022

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ALCORCON ENGINEERING REVIEW CENTER
Cebu: 4TH Flr. Coast Pacific Downtown Center, Sanciangco St. Cebu City (Tel # 254-33-84)
Manila Branch: 3rd floor JPD Bldg 1955, C M Recto corner N. Reyes St, Sampaloc, Manila Tel # (02) 736-4438
Machine Design Problems – DAY 1
MACHINE ELEMENTS
1. PROBLEM (ME Bd. Apr. 97) Two parallel shafts connected by pure rolling turn in the same direction
having a speed ratio of 2.75. What is the distance of the shafts if the smaller cylinder is 22 cm in diameter?
2. Two cylinders rolling in opposite direction has a speed ratio of 3. If center distance is 40 in, find the diameter
of smaller cylinder.
STRESSES
1. PROBLEM (ME Bd. Apr. 96) A steel tie rod on bridge must be made withstand a pull of 5000 lbs. Find the
diameter of the rod assuming a factor of safety of 5 and ultimate stress of 64,000 psi.
2. PROBLEM (ME Bd. Oct. 97) Determine the minimum mean diameter of a taper pin for use to fix a lever to
a shaft, if it is transmit a maximum torque of 700 in-lbs. The shaft diameter is 2 inches and the material
allowable stresses is 15,000 psi. Use factor of safety of 2.
3. PROBLEM (ME Bd. Apr. 97) How many 5/16 inch holes can be punch in one motion in a steel plate made
of SAE 1010 steel, 7/16 inch thick using a force of 55 tons. The ultimate strength for shear is 50 ksi and use 2
factor of safety.
4. PROBLEM (ME Bd. Apr. 97) The shaft whose torque varies from 2000 to 6000 in-lbs has 1 1/2 inches in
diameter and 60,000 psi yield strength. Compute for the shaft mean average stress.
5. In a 2.0 m cantilevered I-beam, a 2 Mton weight is applied at free end. If the allowable stress in beam is 110
Mpa, determine the section modulus.
STRESS AND STRAIN and Poisons Ratio.
1. (ME Bd. Oct. 2000) Compute the induced/compressive stress, in kpa, of a steel solid shafting of 50 mm
diameter and 800 mm in length that is subjected to an increase of temperature by 80oC.
2. (ME Bd. Oct. 2003) What is the decrease in lateral dimension due to an axial tensile force of 50,000 lbs in a
bar 3 inch on each side and 6 feet long? The material is steel (E = 3.0 x 107 psi, μ = 0.3).
SITUATIONAL PROBLEM (Oct 2003)
An 8 inches long bar is elongate to 8.0065 inches for an applied load of 5000 lbs in which its cross-sectional
area is 0.25 in2.
A. Find the modulus of elasticity, psi.
A. 22.62 x 106 psi B. 24.62 x 106 psi C. 26.62 x 106 psi D. 28.62 x 106 psi
B. Find the tensile stress , psi.
A. 20,000 psi B. 15,000 psi C. 20,000 psi D. 25,000 psi
C. Find the strain. A. 6.309 x 10-4 B. 8.12 x 10-4 C. 10.27 x 10-4 D. 12.09 x 10-4
D. Find the stress for a load of 5000 kg, kg/cm2.
A. 2800 B. 2900 C. 3000 D. 3100
E. Find the stress if the bar is heated at a temperature change of 80oF, psi.
A. 15,08.45 B. 10,083.90 C. 5,088.40 D. 12,802.40
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Download Machine Design Problems: A Comprehensive Guide for Engineering Students - Prof. Mendoza and more Summaries Thermodynamics in PDF only on Docsity!

Cebu: 4 TH^ Flr. Coast Pacific Downtown Center, Sanciangco St. Cebu City (Tel # 254-33-84) Manila Branch: 3rd^ floor JPD Bldg 1955, C M Recto corner N. Reyes St, Sampaloc, Manila Tel # (02) 736-

Machine Design Problems – DAY 1

MACHINE ELEMENTS

  1. PROBLEM (ME Bd. Apr. 97) Two parallel shafts connected by pure rolling turn in the same direction having a speed ratio of 2.75. What is the distance of the shafts if the smaller cylinder is 22 cm in diameter?
  2. Two cylinders rolling in opposite direction has a speed ratio of 3. If center distance is 40 in, find the diameter of smaller cylinder.

STRESSES

  1. PROBLEM (ME Bd. Apr. 96) A steel tie rod on bridge must be made withstand a pull of 5000 lbs. Find the diameter of the rod assuming a factor of safety of 5 and ultimate stress of 64,000 psi.
  2. PROBLEM (ME Bd. Oct. 97) Determine the minimum mean diameter of a taper pin for use to fix a lever to a shaft, if it is transmit a maximum torque of 700 in-lbs. The shaft diameter is 2 inches and the material allowable stresses is 15,000 psi. Use factor of safety of 2.
  3. PROBLEM (ME Bd. Apr. 97) How many 5/16 inch holes can be punch in one motion in a steel plate made of SAE 1010 steel, 7/16 inch thick using a force of 55 tons. The ultimate strength for shear is 50 ksi and use 2 factor of safety.
  4. PROBLEM (ME Bd. Apr. 97) The shaft whose torque varies from 2000 to 6000 in-lbs has 1 1/2 inches in diameter and 60,000 psi yield strength. Compute for the shaft mean average stress.
  5. In a 2.0 m cantilevered I-beam, a 2 Mton weight is applied at free end. If the allowable stress in beam is 110 Mpa, determine the section modulus.

STRESS AND STRAIN and Poisons Ratio.

  1. ( ME Bd. Oct. 2000) Compute the induced/compressive stress, in kpa, of a steel solid shafting of 50 mm diameter and 800 mm in length that is subjected to an increase of temperature by 80oC.
  2. ( ME Bd. Oct. 2003) What is the decrease in lateral dimension due to an axial tensile force of 50,000 lbs in a bar 3 inch on each side and 6 feet long? The material is steel (E = 3.0 x 10^7 psi, μ = 0.3). SITUATIONAL PROBLEM (Oct 2003) An 8 inches long bar is elongate to 8.0065 inches for an applied load of 5000 lbs in which its cross-sectional area is 0.25 in^2. A. Find the modulus of elasticity, psi. A. 22.62 x 10^6 psi B. 24.62 x 10^6 psi C. 26.62 x 10^6 psi D. 28.62 x 10^6 psi B. Find the tensile stress , psi. A. 20,000 psi B. 15,000 psi C. 20,000 psi D. 25,000 psi C. Find the strain. A. 6.309 x 10-4^ B. 8.12 x 10-4^ C. 10.27 x 10-4^ D. 12.09 x 10- D. Find the stress for a load of 5000 kg, kg/cm^2. A. 2800 B. 2900 C. 3000 D. 3100 E. Find the stress if the bar is heated at a temperature change of 80oF, psi. A. 15,08.45 B. 10,083.90 C. 5,088.40 D. 12,802.

Cebu: 4 TH^ Flr. Coast Pacific Downtown Center, Sanciangco St. Cebu City (Tel # 254-33-84) Manila Branch: 3rd^ floor JPD Bldg 1955, C M Recto corner N. Reyes St, Sampaloc, Manila Tel # (02) 736-

Machine Design Problems – DAY 2

SHAFT SUBJECTED TO PURE TORSION ONLY

  1. (ME Bd. Oct. 1998) What power would a spindle 55 mm in diameter transmit at 480 rpm stress allowed for short shaft is 59 N/mm^2?
  2. (ME Bd. Oct. 2000) Find the torsional deflection, in degrees, of a solid steel shaft, 110 mm OD x 1.4 m long subject to 3.1 x 10^6 N-mm torque. The torsional modulus of elasticity is 80,000 N/mm-mm.
  3. (ME Bd. Apr. 96) Compute the linear shaft diameter to transmit 12 HP at 180 rpm with torsional deflection of 0.08 degrees per foot length.
  4. (ME Bd. Apr. 95) A hollow shaft with outside diameter of 14 cm and wall thickness of 0.8 cm transmits 200 KW at 400 rpm. What must be the angular deflection of the shaft if the length is 5 meters? The material of the shaft is C4140 steel. SHAFT WITH ASSUMED ALLOWABLE STRESS & SUBJECTED TO TORSION AND BENDING LOAD
  5. (ME Bd. Oct. 95) A short 61 mm diameter shaft transmits 120 Hp. Compute the linear speed of a pulley 55 cm diameter mounted on the shaft.
  6. A machine shaft is supported on bearings 1 m apart is to transmit 190 KW at 300 rpm while subjected to bending load of 500 kg at the center. If maximum shearing stress is 40 Mpa, determine the shaft diameter. FROM MACHINERIES HANDBOOK
  7. (ME Bd. Apr. 98) A 16 ft lineshaft has no bending action except its own weight. What power in Hp can the shaft deliver at a speed of 200 rpm. Consider that the torsional deflection will not exceed 0.08/ft length.

SITUATIONAL PROBLEMS

(ME Bd. APRIL 2004) A hollow shaft has an outside diameter of 2in. The allowable shearing stress of the shaft is 7,000 psi and the applied torque is 700 in-lbs. Find: A. the shaft inside diameter, in A. 1.95 in B. 1.93 in C. 1.91 in D. 1.97 in B. the equivalent solid shaft diameter, in A. 0.788 B. 0.798 C. 0.792 D. 0. C. savings in weight if the solid shaft is to be replaced with hollow shaft of the same torsional strength. A. 76.20% B. 78.20% C. 81.29% D. 85.30% D. the factor of safety if yield stress is 10,430 psi. A. 1.49 B. 1.69 C. 1.79 D. 1. E. tangential force of the solid shaft, lbs A. 1754.39 B. 1854.39 C. 1954.39 D. 2054.

Cebu: 4 TH^ Flr. Coast Pacific Downtown Center, Sanciangco St. Cebu City (Tel # 254-33-84) Manila Branch: 3rd^ floor JPD Bldg 1955, C M Recto corner N. Reyes St, Sampaloc, Manila Tel # (02) 736-

Machine Design Problems – DAY 4

BOLTS AND POWER SCREW

1. (Oct. 1998) Compute the working strength of 1 in bolt is screwed up tightly in packaged joint when the allowable stress is 13,000 psi. A. 3,600 lbs B. 3,700 lbs C. 3,800 lbs D. 3,900 lbs 2. (ME Bd. Oct. 97) An eyebolt is lifting a block weighing 350 lbs. The eyebolt is of SAE C 1040 material with S u = 67 ksi and Sy = 55 ksi, what is the stress area ( in inches square) of the bolt if it is under the unified coarse series thread? A. 0.1341 B. 0.1134 C. 0.0991 D. 0. 3. (ME Bd. Apr. 98) Compute how many 3/8 inch diameter set screws required to transmit 3 Hp at a shaft speed of 1000 rpm. The shaft diameter is 1 inch. A. 1 1/2 B. 2 C. 3 D. 1 4. (ME Bd. Apr. 95) What is the frictional Hp acting on a collar loaded with 100 kg weight? The collar has an outside diameter of 100 mm and an internal diameter of 40 mm. The collar rotates at 1000 rpm and the coefficient of friction between the collar and the pivot surface is 0.15. A. 0.8 Hp B. 0.3 Hp C. 0.5 Hp D. 1.2 Hp 5. A double square thread power screw has a mean radius of 80 mm and a pitch of 10 mm is use to lift a load of 80 KN. If friction of screw is 0.13 and collar torque is 20% of input torque, determine the input torque required. A. 830.76 N-m B. 835.76 N-m C. 1246.30 N-m D. 1365.30 N-m

  1. A power screw that has 2 ½ inches mean diameter with two thread per inch is to be used. The frictional radius of collar is 2 inches and coefficient of friction are 0.10 for the threads and 0.15 for collar. The velocity of the nut is 10 ft/min. For a lifting load of 5000 lbs, find: A. the efficiency of the screw for a double square thread. B. the power output of the screw for a double square thread.

Cebu: 4 TH^ Flr. Coast Pacific Downtown Center, Sanciangco St. Cebu City (Tel # 254-33-84) Manila Branch: 3rd^ floor JPD Bldg 1955, C M Recto corner N. Reyes St, Sampaloc, Manila Tel # (02) 736-

MACHINE DESIGN – DAY 5

WORM GEAR

  1. (ME Bd. Oct. 97) A triple thread worm has a pitch diameter of 3 inches. The wheel has 25 teeth and a pitch diameter of 5 inches. Material for both the worm and the wheel is of phosphor bronze. Compute the helix angle (tan ). A. 0.20 B. 0.30 C. 0.40 D. 14
  2. Two-thread worm gear, rotating at 1200 rpm, drives a 26-tooth worm gear and transmit 10 hp. The worm has 14.5o^ teeth with 0.5 pitch, 2 in pitch diameter, and an included face angle of 60o. The coefficient of friction is 0.06. (Assume: y = 0.212) A. Determine the lead angle of the worm. B. Determine the speed ratio. C. Determine the center distance. BEVEL GEAR
  3. A pair of straight-tooth bevel gears are mounted on the shafts that intersect each other at an angle of 70o. The velocity ratio is ½. Determine the angles of the gear and pinion. Also determine the pitch diameter of the pinion if gear diameter is 15 cm. HELICAL GEARS:

1. A helical gear has a helix angle of 25o^ and transverse circular pitch of π/5. The number of teeth for the

pinion and gear 15 and 45, respectively. A) determine the normal circular pitch B) determine the pitch diameter of the pinion and gear C) determine the center distance

  1. A steel pinion having a diameter of about 254mm meshes with a helical gear which turns one-fifth the angular speed of the pinion. The normal diametral pitch to be 4 and the teeth is to be 20o. Determine the required number of teeth for the pinion and gear.

Cebu: 4 TH^ Flr. Coast Pacific Downtown Center, Sanciangco St. Cebu City (Tel # 254-33-84) Manila Branch: 3rd^ floor JPD Bldg 1955, C M Recto corner N. Reyes St, Sampaloc, Manila Tel # (02) 736-

MACHINE DESIGN – DAY 7

CLUTCHES:

  1. (Board Exam April 97) If the inertia is 90 lb-ft^2 and the speed of the driven shaft is to be increased from 0 to 2500 in 5 seconds, shaft material is of SAE 4140 with yield strength of 110,000lb/in^2 , find the clutch starting torque in ft-lb. (Ans. 146)
  2. Assuming uniform wear, find the power capacity of a simple disc clutch with an outside and inside diameter of 200mm and 100mm, respectively. A rotational speed of 1160rpm and coefficient of friction of 0.35 whose axial operating force is 800N. (Ans. 2.55KW)
  3. A cone clutch has cone elements at an angle of 10o. The clutch transmits 20 hp at a speed of 100 rpm. The mean diameter of the conical friction sections is 16 in and the coefficient of friction is 0.3. Find the axial force needed to engage the clutch. A. 246.37 lbs B. 212.56 lbs C. 234.56 lbs D. 346.78 lbs
  4. The angle of contact of a band clutch is 250 degrees. The cross section of the band is 1/16 in x 1.5 in. The design stress for the band material is 8,000 psi. If the drum is 16 inches in diameter and rotates at 350 rpm, what is the horsepower capacity of the clutch? The coefficient of friction is 0.4. A. 20.34 hp B. 15.23 hp C. 22.34 hp D. 27.50 hp

BRAKES:

  1. The band brake of a band brake has 210 degrees of contact with its drum. By laboratory tests, it is found that the pull on the tight side is 800 lbs and the pull on the slack side is 285 lb. What is the coefficient of friction? A. 0.281 B. 0.753 C. 0.186 D. 0.
  2. A band brake is to operate on a 650mm diameter drum rotating at 250rpm. The coefficient of friction between band and drum is 0.25. The band brake has an angle of contact of 1.5π radians and band width is 65mm. One end of the band is fastened to the fixed end pin at the end of the lever while the other end on the brake arm 120mm from the fixed pin and is placed perpendicular to the diameter bisecting the angle of contact. The brake arm length is 750mm. Calculate the following: A. torque capacity if the band pressure is not to exceed 290kpa B. what is the minimum pull necessary at the end of the lever arm in order to absorb the torque? C. how much power can be handled at the given speed? D. tensile stress in the band if the band thickness is 15mm.

Cebu: 4 TH^ Flr. Coast Pacific Downtown Center, Sanciangco St. Cebu City (Tel # 254-33-84) Manila Branch: 3rd^ floor JPD Bldg 1955, C M Recto corner N. Reyes St, Sampaloc, Manila Tel # (02) 736-

MACHINE DESIGN – DAY 8

WELDED JOINTS

  1. A 16mm plate is lapped over and secured by fillet weld on the inside and outside to form a penstock 1.5m in diameter. Determine the safe internal pressure, assuming an allowable stress of 140Mpa on the plate and allowable shear stress of 90Mpa on the throat side of the 14mm fillet weld. (Ans. 2375.76 kpa) RIVETED JOINTS
  2. Consider a section of 304.8mm of a single-riveted lap joint made with plates of 6.35mm thickness and 6 rivets, 15.87mm in diameter. Assume that rivet holes are 1.58mm larger in diameter than the rivets. In this joint, the entire load is transmitted from one plate to the other by means of rivets. Each plate and the six rivets carries the entire load. The design stresses are: for shear = 589 kg/cm^2 for bearing = 1,406 kg/cm^2 for tension = 703 kg/cm^2 Calculate the following: a) force that can be carried by un punched plate (Ans. 13,606.4 kg) b) force that cause tensile stress on plate between rivets (Ans. 8,932.6 kg) c) force that cause shearing stress on rivets (Ans. 8,580.90 kg) d) force that cause bearing stress in the rivets (Ans. 9,347.7 kg) e) rivet efficiency (Ans. 63.1%) WIRE ROPES What is the factor of safety when a ½ in diameter rope, 6 x 19 MPS wire rope carrying 4000 lb load is bent around an 18 in sheave. If the load