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Important Question ESE Mechanical Engineering
Q1. A reaction-bonded silicon nitride ceramic has a strength of 300 MPa and a fracture toughness of . With in thefracture toughness equation, what is the largest size of internal crack that this material can withstand without fracturing?
- 91.6
- 82.3
- 74.6
- 45.8
Answer: D
Q2. The modulus of elasticity of E-glass is 72 GPa and that of epoxy resin is 3 GPa. The modulus of elasticity (to the nearest unit magnitude) for a composite material consisting of 60% by volume of continuous E-glass fibre and 40% epoxy resin for the matrix, when stressed under isostress conditions, is
- 4 GPa
- 5 GPa
- 6 GPa
- 7 GPa
Answer: D
- In developing abrasive ceramics which are used to wear, grind or cut away other materials which are (necessarily) softer, they should have, besides wear resistance,
- a high degree of toughness
- a low degree of toughness
- refractoriness
Which of the above is/are correct?
(a) 1 only
(b) 2 only
(c) 1 and 3
(d) 2 and 3
Ans. (c)
- Consider the following in case of high-energy forming processes :
- The evacuation between die and blank in explosive forming is done by a vacuum pump.
- The pressure waves produced in water in explosive forming deform the blank to the die shape.
- The electrohydraulic forming makes use of discharge of large amount of electrical energy used in a capacitor blank.
- In Petroforge, the piston is moved by combustion of fuel moving at the rate of 150-200 m/s.
Which of the above are correct?
(a) 1, 2, 3 and 4
(b) 1, 2 and 3 only
(c) 3 and 4 only
(d) 1, 2 and 4 only
Ans. (a)
Q5. In abrasive jet machining process, the main mechanism of material removal takes place due to
- electrochemical action
- mechanical impact
- fatigue failure of the material
- sparking on impact
Answer: B
6.Consider that the following materials are usable for manufacturing dies, moulds in investment casting process for the purpose of large-scale production :
- Aluminum alloy
- Magnesium alloy
- Brass
- Low-carbon steel
Which of the above are correctly usable?
(a) 1, 2 and 3 only
(b) 1, 2 and 4 only
(c) 3 and 4 only
(d) 1, 2, 3 and 4
Ans. (c)
- The occurrence of casting defect โrat tailโ is possible because of
- soft ramming of sand
- continuous large flat surface on the mould
- excessive hardness of the mould
Which of the above reasons are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Ans. (b)
Q8. Components produced by die casting have finer grain, higher strength and greater hardness at the skin than at the centre due to
- decreased wall thickness of die cavity
- rapid chilling of molten metal at the die walls
- high temperature involved in the process
- high tonnage of die casting machines
Answer: B
Q9. A 125 mm long, 10 mm diameter stainless steel rod is being turned to 9 mm diameter, 0.5 mm depth of cut. The spindle rotates at 360 r.p.m. With the tool traversing at an axial speed of 175 mm/min, the metal removal rate is nearly
- 2200 mm 3 /min
- 2400 mm 3 /min
- 2600 mm 3 /min
- 2800 mm 3 /min
Answer: C
Q10. The feed in face milling for a width of 70 mm with a cutter of 160 mm diameter, having 10 inserts and rotating at 360 r.p.m., with a feed rate of 0.5 m/min, is nearly
- 0.21 mm/tooth
- 0.18 mm/tooth
- 0.14 mm/tooth
- 0.11 mm/tooth
Answer: C
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