GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER- V(OLD) EXAMINATION - SUMMER 2019
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Subject Code: 151905 Date: 17/06/2019
Subject Name: Machine Design - 1
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
- Attempt all questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
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Q.1 (a) What is the importance of wear considerations in design? Explain the measures to minimize the wear. 07
(b) Explain the following terms: 07
- Notch sensitivity
- Standardization
- Endurance limit
- Hertz’s Contact stress
- Creep
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Q.2 (a) Explain the following: 07
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- Soderberg diagram for fatigue loading.
- Design for ergonomics.
(b) A component machined from a plate made of steel 45C8 (Su = 630 N/mm²) is shown in Fig. A. It is subjected to a completely reversed axial force of 50 kN. The expected reliability is 90% and the factor of safety is 2. The size factor is 0.85. Determine the plate thickness t for infinite life, if the notch sensitivity factor is 0.8. 07
OR
(b) A rotating bar made of steel 45C8 (Su = 630 N/mm²) is subjected to a completely reversed bending stress. The corrected endurance limit of the bar is 315 N/mm². Calculate the fatigue strength of the bar for a life of 90,000 cycles. 07
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Q.3 (a) Compare the belt and chain drive. Discuss the different types of belts and their material used for power transmission. 07
(b) Explain Following 07
- State and explain the factors affecting the selection of a suitable antifriction bearing.
- Explain the effects of the L/D ratio and C/D ratio parameters on the performance of journal bearing.
OR
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Q.3 (a) Explain Lubricant and properties of lubricants for sliding contact bearing. 07
(b) What are the salient features used in the design of forging? Explain. 07
Q.4 (a) Describe the series of preferred numbers. Standardize six speeds between 250 to 1400 rpm and State the series of torque for 0.5 kW drive. 07
(b) Write a detailed note on disc (belleville) springs and explain the buckling of spring. How can it be prevented? 07
OR
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Q.4 (a) Explain the different types of end covers used in pressure vessels. 07
(b) Define the following terminology related to helical spring with neat sketch: 07
- Spring index
- Spring stiffness
- Pitch
- Wahl’s stress factor
- Free length
- Solid length
- Surge in spring.
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Q.5 (a) What is Self energizing and self locking brake? What is the condition of self-locking in differential band brake? Why it should be avoided in speed control brake? 07
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(b) Discuss the advantages and limitations. 07
OR
Q.5 (a) What are the design consideration points in the design of a friction clutch? Discuss briefly the considerations for selection of friction lining material. 07
(b) The center to Centre distance between two sprockets of a chain drive is 600 mm. The chain drive is used to reduce the speed from 180 rpm to 90 rpm on the driving sprocket has 18 teeth and a pitch circle diameter of 480 mm. Determine 07
- No. of teeth on the driven sprocket
- Pitch and the length of chain.
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