JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II DESIGN OF MACHINE MEMBERS I Previous Question Paper (May - 2019 - R16)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
How the loads coming on to a component be classified and mention their importance?
Answer
Loads are classified as static (constant magnitude and direction over time) and dynamic (varying magnitude or direction, such as fluctuating, alternating, or shock loads). Their importance lies in determining the fatigue life, safety factor, and material selection for a component to prevent failure.
Differentiate between allowable stress and ultimate stress.
Answer
Ultimate stress is the maximum stress a material can withstand before failure, determined from a standard tensile test. Allowable stress (or working stress) is the safe stress level calculated by dividing the ultimate stress by a factor of safety to ensure the component operates safely under normal conditions.
What is the effect of crack and hole on the parts?
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What are the sources of stress concentration?
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How a riveted joint fails and mention the reasons?
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What are the advantages of riveted joint over others?
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What are the various couplings used and mention their merits.
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What are the requirements of a good coupling?
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What are the stresses induced in the shafts?
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Differentiate between shaft and axle.
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Part B
What factors are to be considered in the design of machine elements.
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A shaft of diameter 90 mm is subjected to a bending moment of 1200 Nm and a twisting moment of 7500 Nm. Find (i) Maximum normal stress and (ii) maximum shear stress induced.
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Explain about maximum shear stress theory.
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A bolt is subjected to an axial force of 10 kN with a transverse shear force of 5 kN. The permissible tensile stress at elastic limit is 100 Mpa and poison’s ratio is 0.25, for the bolt material. Determine the diameter of bolt required according to: i) maximum principal stress theory ii) maximum shear stress theory.
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What are the methods adopted to reduce stress concentration?
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A connecting rod is subjected to a completely reversed axial load of 100 kN. Determine the diameter of rod using a factor of safety of 3. The ultimate strength of rod is 460 Mpa and yield strength of 350 Mpa.
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A 50 mm diameter shaft is made from steel with UTS of 700 N/mm2. It is subjected to a torque which fluctuates between +2000 N-m to – 800 Nm using soderberg method, calculate the factor of safety.
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How the pitch and nominal diameter bolt is found?
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A flange is fastened to a frame by means of 8 bolts on 600 mm pitch circle. The diameter of bearing flange is 800 mm and a load of 210 kN acts at a distance 380 mm from the frame. Determine the size of the bolts, assuming tensile stress as 100 N/mm2.
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How a lozenze joint is prepared?
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A triple riveted lap joint is to be designed to connect plates of 10 mm thickness. Find the diameter of rivet, pitch and raw pitch. How the joint fails and also find the efficiency of joint, the permissible stresses are 130Mpa in tension, 90 Mpa in shear and 160Mpa is crushing.
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What is the effect of key way on the strength of shaft?
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A solid shaft is subjected to a bending moment of 3.5 kN-m and a torque of 1.5 kN-m. Determine the diameter of shaft if factor of safety is 5, if ultimate bending stress is 700 N/mm2 and ultimate shear stress 600 N/mm2.
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Design a sleeve and cotter joint to two shafts whose diameter is 30 mm.
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Design a C.I flange coupling to transmit power at 60 kw at 800 rpm. The permissible shear and crushing stresses for shaft, bolt and key material is 50 N/mm2 and 80 N/mm2 permissible shear stress for C.I flange is 40 N/mm2.
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How the springs are classified?
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Design a spring to be used on a value subjected to a load range of 120 to 175 N(i.e.) 120 N when the value is closed and 175 N, when it is open. The deflection of spring (i.e) the value lift during the above load range is 6 mm. Take spring index as 10. Determine the size of wire, size and number of coils and pitch of the coil.
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