B.TECH - Semester 6 design of machine elements i Question Paper 2013 (apr)
Practice authentic previous year university questions for better exam preparation.
- Design a leaf spring to carry a load of 3400 N and placed over a span of 800 mm . The spring can deflect by 50 mm . Consider, allowable bending stress for the spring material as 350 MPa and $\mathrm{E}=2 \times 10^{5} \mathrm{MPa}$.
- Design a helical spring of wire diameter 6 mm and spring index 6 is acted by an initial load of 800 N . After compressing it further by 10 mm the stress in the wire is $500 \mathrm{MPa} . \mathrm{G}=84000 \mathrm{MPa}$. ( $4 \times 20=80$ Marks)
- What is the curvature effect in a helical spring? How does it vary with spring index?
- What do you understand by shaft, axle and spindle?
- What should be essential qualities of a rivet and its material? ( $\mathbf{5} \boldsymbol{\times} \mathbf{4} \boldsymbol{=} \mathbf{2 0}$ Marks) P.T.O. (Answer any one questions from each Module. Each carries 20 marks)
- The state of stress at a point for a material is shown in figure below. Find the factor of safety using (a) Maximum shear stress theory (b) Maximum distortion energy theory. Take the tensile yield strength of the material as 400 MPa .
- Find the diameter of a solid steel shaft to transmit 20 kW at 200 r.p.m. The ultimate shear stress for the steel may be taken as 360 MPa and a factor of safety as 8.If a hollow shaft is to be used in place of the solid shaft, find the inside and outside diameter when the ratio of inside to outside d...
- A universal coupling is used to connect two mild steel shafts transmitting a torque of $5000 \mathrm{~N}-\mathrm{m}$. Assuming that the shafts are subjected to torsion only, find the diameter of the shafts and pins. The allowable shear stresses for the shaft and pin may be taken as 60 MPa and 28-MPa...
- Two plates of 7 mm thickness are connected by a double riveted lap joint of zigzag pattern. Design the joint. Assume allowable tensile stress of the plate material $=90 \mathrm{MPa}$, allowable shear stress of the rivet material $=60 \mathrm{MPa}$ and allowable bearing stress between the rivet and p...
- A plate 50 mm wide and 12.5 mm thick is to be welded to another plate by means of parallel fillet welds. The plates are subjected to a load of 50 kN . Find the length of the weld. Assume allowable shear strength to be 56 MPa .
- Differentiate between maximum principal stress and maximum shear stress theories of failure.
- Explain different methods to reduce stress concentration in machine parts.
- A Circular bar of 600 mm length is supported freely at its ends. It is acted upon by a central concentrated cyclic load having a minimum value of 30 KN and a maximum value of 80 KN . Determine the diameters of bar by taking a safety factor 2.1 , size factor 0.82 and surface finish factor of 0.89 . A...
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