QP

1. Note: Answer all
PART-A(3X10=30)
1. Define ductility.
2. Define elastic limit.
3. State Hooke’s law.
4. Define centre of gravity.
5. What are the stresses are developed in a cylindrical shell due to an internal pressure?
6. Define thin cylindrical shell.
7. What do you mean by strength of a shaft?
8. Define stiffness of the spring.
9. Define polar modulus.
10. State the applications of spring.
PART-B(14X5=70)
11.a. List out the types of cast iron. Explain the effects of impurities in cast iron.
Or
b. Explain the stress-strain diagram for mild steel specimen with its salient points. (Tension
test on ductile material in UTM)
12.a. Find the values of Ixx and Iyy of a T section 120mm wide and 120 mm deep overall. Both
the web and flange are 10 mm thick. Also find out its radius of gyration about its axes.
Or
b. A channel section of size 300mm and 100mm overall. The base as well as flange of the
channel are 10 mm thick. Calculate the moment of inertia about its centroidal axes.
13. a. A cylindrical shell 3 m long 500mm in diameter is made up of 20 mm thick plate. If the
cylinder is subjected to an internal pressure of 5 N/mm2
, find the resulting hoop and longitudinal
stress, change in diameter, change in length and change in volume. Take Poisson’s Ratio as 0.3
and E = 2x105
N/mm2
.
Or
b. An I section has the top flange 100mmx 15mm, web is 150mm x20mm and the bottom flange
180mmx 30 mm. Calculate the moment of inertia Ixx and Iyy.
14.a. A solid shaft is transmitting 100 KW at 180 rpm. If the allowable shear stress is 60 N/mm2
,
find the necessary diameter for the shaft. The shaft is not twist more than 1⁰ in a length of 3 m.
Take C = 80KN/mm2
.
Or

2. b. Design a closely coiled helical spring of stiffness 20 N/mm. the maximum shear stress in the
spring material is not to exceed 80 N/mm2
under a load of 600 N. the diameter of coil is to be 10
times the diameter of wire. Take C = 85x103
N/mm2
.
15.a. A hollow shaft having inner diameter is 0.6 times the outer diameter is to be replaced by a
solid shaft of the same material to transmit 550 KW at 220rpm.The permissible shear stress is 80
N/mm2
. Calculate the diameters of the hollow and solid shafts. Also calculate the percentage of
saving in material.
Or
b. A closely coil helical spring made of steel wire of 10 mm diameter has 10 coils of 120 mm
mean diameter. Calculate the deflection of the spring under an axial load of 100 N and the
stiffness of spring.