JNTU B.Tech III DESIGN OF MACHINE MEMBERS I Previous Question Paper (August/September - 2024 - R16)

What are the guidelines for selection of transition fits? Give examples?

Why is it necessary to use factor of safety?

What is meant by endurance strength of a material?

Illustrate how the stress concentration in a component can be reduced.

How will you designate ISO metric coarse threads?

What are the different types of rivet heads? Give their applications

Why cotter is provided with taper? Why taper is provided on only one side?

What is the effect of keyway cut into the shaft?

Discuss the function of a coupling. Give at least three practical applications.

How the shaft is designed when it is subjected to twisting moment only?

What are the common materials used in Mechanical Engineering Design? How can the properties of steel be improved?

What is meant by ‘hole basis system’ and ‘shaft basis system’? Which one is preferred and why?

What are the important theories of elastic failures? Explain any one theory related to ductile material?

A beam of uniform rectangular cross-section is fixed at one end and carries an electric motor weighing 400 N at a distance of 300 mm from the fixed end. The maximum bending stress in the beam is 40 MPa. Find the width and depth of the beam, if depth is twice that of width.

Explain the modified Goodman diagram for torsional shear stresses.

A 25 mm diameter shaft is made of forged steel 30C8 (Sut = 600 N/mm²). There is a step in the shaft and the theoretical stress concentration factor at the step is 2.1. The notch sensitivity factor is 0.84. Determine the endurance limit of the shaft, if it is subjected to a reversed bending moment.

What are the causes of stress concentration? What are the methods of reducing stress concentration?

A solid circular shaft, 15 mm in diameter, is subjected to torsional shear stress, which varies from 0 to 35 N/mm² and at the same time, is subjected to an axial stress that varies from –15 to +30 N/mm². The frequency of variation of these stresses is equal to the shaft speed. The shaft is made of steel FeE 400 (Sut = 540 N/mm² and Syt = 400 N/mm²) and the corrected endurance limit of the shaft is 200 N/mm². Determine the factor of safety.

Explain the different types of weld symbol and its importance.

A welded connection is subjected to an eccentric force of 7.5 kN. Determine the size of welds if the permissible shear stress for the weld is 100 N/mm². Assume static conditions.

Why are riveted joints replaced by welded joints? Explain.

A gearbox weighing 7.5 kN is provided with a steel eye bolt for lifting and transporting on the shop-floor. The eyebolt is made of plain carbon steel 30C8 (Syt = 400 N/mm²) and the factor of safety is 5. Determine the nominal diameter of the eye bolt having coarse threads if, dc = 0.8d where dc and d are core and major diameters respectively.

Explain the construction of Knuckle joint with a neat sketch.

Design a cotter joint to connect piston rod to the crosshead of a double acting steam engine. The diameter of the cylinder is 300 mm and the steam pressure is 1 N/mm². The allowable stresses for the material of cotter and piston rod are: σt = 50 MPa ; τ = 40 MPa ; and σc = 84 MPa.

What is Gib head taper sunk key? What is its advantages and disadvantages?

A shaft 30 mm diameter is transmitting power at a maximum shear stress of 80 MPa. If a pulley is connected to the shaft by means of a key, find the dimensions of the key so that the stress in the key is not to exceed 50 MPa and length of the key is 4 times the width.

How will you design of shaft as per ASME code?

A hollow shaft is subjected to a maximum torque of 1.5 kN-m and a maximum bending moment of 3 kN-m. It is subjected, at the same time, to an axial load of 10 kN. Assume that the load is applied gradually and the ratio of the inner diameter to the outer diameter is 0.5. If the outer diameter of the shaft is 80 mm, find the shear stress induced in the shaft.

What are the advantages and disadvantages of flange coupling?

Design a muff coupling to connect two shafts transmitting 40 kW at 120 r.p.m. The permissible shear and crushing stress for the shaft and key material (mild steel) are 30 MPa and 80 MPa respectively. The material of muff is cast iron with permissible shear stress of 15 MPa. Assume that the maximum torque transmitted is 25 percent greater than the mean torque.