Calculate the work done per minute by a punch tool making 20 working strokes per min when a 30 mm diametre hole is punched in 5 mm thick plate with ultimate shear strength og 450 Mpa in each stroke.

When a hole of diameter ‘d’ is punched in a metal of thickness 't', then the force required to punch a hole is equal to (where $${\tau _{\text{u}}}$$ = Ultimate shear strength of the material of the plate)

A

$${\text{dt}}{\tau _{\text{u}}}$$

B

$$\pi {\text{dt}}{\tau _{\text{u}}}$$

C

$$\frac{\pi }{4} \times {{\text{d}}^2}{\tau _{\text{u}}}$$

D

$$\frac{\pi }{4} \times {{\text{d}}^2} \times {\text{t}}{\tau _{\text{u}}}$$

A hole of diameter (d) is to be punched through a sheet metal of thickness (t). How much force is required to punch the hole if the ultimate shear stress of the sheet metal is (τ)?

A

dtτ

B

$\frac{\pi }{4}{d^2}t\tau $

C

πdtτ

D

$\frac{\pi }{4}{d^2}\tau $

To effect a bond between two metal plates, 2.5 cm and 15 cm thick, heat is uniformly applied through the thinner plate by a radiant heat source. The bonding must be held at 320 K for a short time. When the heat source is adjusted to have a steady value of 43.5 k W/m2, a thermocouple installed on the side of the thinner plate next to source indicates a temperature of 345 K. Calculate the temperature gradient for heat conduction through thinner plate. In the diagram, the upper plate is 2.5 cm thick while the lower is 15 cm thick.

A

– 1000 degree Celsius/m

B

– 2000 degree Celsius/m

C

– 3000 degree Celsius/m

D

– 4000 degree Celsius/m

The maximum diameter of the hole that can be punched from a plate of maximum shear stress $${\frac{1}{4}^{{\text{th}}}}$$ of its maximum crushing stress of punch, is equal to (where t = Thickness of the plate)

A

1t

B

2t

C

4t

D

8t

For a given component, the alternating stress is equal to 250 MPa, Mean stress is 100 MPa, and the ultimate tensile strength is 500 MPa. Find the yield strength of the material according to Goodman’s approach?

A

3125.5 MPa

B

312.5 MPa

C

5215.3 MPa

D

521.5 MPa

For a given component, the alternating stress is equal to 250 MPa, Mean stress is 100 MPa, and the ultimate tensile strength is 500 MPa. Find the yield strength of the material according to the Gerber’s approach?

A

521 MPa

B

694 MPa

C

45 MPa

D

55 MPa

A rock specimen of average thickness 0.8 cm failed at an applied load of 1000 kg during determination of shear strength by the punch test. The diameter of the punch is 2.8 cm, The shear strength of the rock specimen in kg/ cm² is

A

50.75

B

142.10

C

284.20

D

446.43

A body starts yielding when it is subjected to stress state with principal stresses of 250 MPa, 50 MPa and - 50 MPa. What is the yield strength of the material. in MPa, if Tresca yield criterion is obeyed?

A

100

B

200

C

300

D

400

If d=depth of cut in mm, f=feed in mm/stroke, n=stroke/min, l=length of stroke in mm, m= ratio of return stroke time to cutting stroke time, then find the formula for metal removal rate.

A

f*d*l*n*(m+1)

B

f*d*l*n*m

C

f*d*l*n*m/1000

D

none of the mentioned

Zubin and Pravin can individually complete a job in 36 min and 60 min respectively. Starting with Zubin, they work alternately for a minute each till the work is completed, only the one working at the end allowed to work for less than a minute in his final turn. How long will it take the due to complete the job?

A

45 min

B

44min 48 s

C

44 min 45 s

D

45 min 12 s

Calculate the work done per minute by a punch tool making 20 working strokes per min when a 30 mm diametre hole is punched in 5 mm thick plate with ultimate shear strength og 450 Mpa in each stroke.

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