Automotive Engine Components Design Multiple Choice Questions on “IC Engine – Big End Cap and Bolts”.
1. Which force is experienced by the connecting rod cap?
a) Gravity force
b) Magnetic force
c) Axial force
d) Inertia force
Answer: d
Clarification: The maximum force experienced by the connecting rod cap and bolts consists only of inertia force at the top dead Centre on the exhaust stroke. Hence, the inertia force is experienced by the connecting rod cap.
2. At which position of the piston, connecting rod cap experience inertia force?
a) Center
b) Side dead center
c) Top dead center
d) Bottom dead center
Answer: c
Clarification: The maximum force experienced by the connecting rod cap and bolts consists only of inertia force at the top dead center on the exhaust stroke. Hence, connecting rod cap experience inertia force at the top dead center.
3. Inertia force acting on the connecting rod cap is given by?
a) Pi=mrω2 r(θ+(frac{cos2theta}{n_1}))
b) Pi=mrω2 r(cosθ+(frac{sin2theta}{n_1}))
c) Pi=mrω2 r(cosθ+(frac{cos2theta}{n_1}))
d) Pi=mrω2 r(secθ+(frac{cos2theta}{n_1}))
Answer: c
Clarification: Pi=mrω2 r(cosθ+(frac{cos2theta}{n_1}))is the right answer where Pi is the inertia force, mr is the mass of reciprocating parts, ω is the angular velocity of the crank, r is the crank radius, n1 is the ratio of L/r and θ is the angle of inclination.
4. Calculate the mass of reciprocating parts when the mass of piston assembly is 0.6Kg and mass of the connecting rod is 0.4Kg?
a) 0.73Kg
b) 0.85Kg
c) 0.6Kg
d) 0.43Kg
Answer: a
Clarification: mr= mass of piston assembly+ (frac{1}{3})mass of connecting rod
= 0.6+(frac{1}{3}) (0.4)
= 0.73Kg
5. Find the crank radius when the length of the stroke is 80mm?
a) 10mm
b) 40mm
c) 30mm
d) 50mm
Answer: b
Clarification: Crank radius r=(frac{l}{2})
=(frac{80}{2})
=40mm
6. Find the angular velocity of the crank rotating at 1200RPM?
a) 100.86rad/sec
b) 112.54rad/sec
c) 125.65rad/sec
d) 134.89rad/sec
Answer: c
Clarification: ω=(frac{2times pitimes N}{60})
=(frac{2times pitimes 1200}{60})
= 125.66 rad/sec
7. In the formula (Pi)max=mrω2r(1+(frac{1}{n_1})) what is mr?
a) Mass of reciprocating parts
b) Mass of all parts
c) Mass of cylinder
d) Mass of crankshaft
Answer: a
Clarification: In this formula, (Pi)max is the maximum inertia force, mr is the mass of reciprocating parts, ω is the angular velocity of the crank, r is the crank radius, n1 is the ratio of L/r.
8. Calculate the inertia force where the diameter of bolts is 10mm and σt=35N/mm2?
a) 5555.5N
b) 6107.8N
c) 6478.6N
d) 5497.7N
Answer: d
Clarification: (Pi)max=2((frac{pitimes d_c^2}{4}))σt
=2((frac{pitimes 10^2}{4}))× 35
=5497.7N
9. Calculate the bending moment on the cap when (Pi)max=400N and span length is 80mm.
a) 3567.9N-mm
b) 4789N-mm
c) 5333.3N-mm
d) 6893.89N-mm
Answer: c
Clarification: Mb=(frac{(P_i)_{max}l}{6})
=(frac{400×800}{6})
=5333.3N-mm
10. Calculate the thickness of cap when σb=100N/mm2, Mb=90853.95N-mm, y=(frac{t_c}{2}) and I=6.25tc3?
a) 7.65mm
b) 8.53mm
c) 9.7mm
d) 6.23mm
Answer: b
Clarification: σb=(frac{M_b times y}{I})
100=(frac{90853.95times frac{t}{2}}{6.25t^3})
tc=8.53mm