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Impact Sheet

The document contains 9 questions about impact testing and material properties. It asks about the potential energy and striking velocity of an impact tester, stresses induced in steel bars under tension and impact loads, efficiency of beams under different loading conditions, and stresses developed in rods and cables from impact and stopping loads.

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mohamed.hassan031
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77 views2 pages

Impact Sheet

The document contains 9 questions about impact testing and material properties. It asks about the potential energy and striking velocity of an impact tester, stresses induced in steel bars under tension and impact loads, efficiency of beams under different loading conditions, and stresses developed in rods and cables from impact and stopping loads.

Uploaded by

mohamed.hassan031
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Impact Sheet

1) The weight of the pendulum of an impact tester is 20 Kg and the length of the
pendulum arm is 800 mm. If the arm is horizontal before striking the specimen,
what is the potential energy of the tester? What is the striking velocity?

2) The Izod test does not lend itself to testing specimens as a function of
temperature, why?

3) A steel bar 25 mm in diameter and 1800 mm long is put in tension by a force of


350 Kg suddenly. Determine the maximum elongation produced. What load,
suddenly applied, would produce an extension of 1.75 mm. E = 210 GPa.

4) A steel bar [A] is 25 mm in diameter over 50 mm of length, and 20 mm in


diameter over 200 mm length. Steel bar [B] is 25 mm over 200 mm of length and
20 mm in diameter over 50 mm length. A sudden axial blow sufficient to cause a
stress of 230 MPa is delivered to [B], what will be the stress in [A] for the same
energy input? How much more energy will [A] store than [B] if both are stressed
up to the proportional limit?

5) Show that with elastic conditions, a freely supported rectangular beam, long
side horizontal, when loaded with an energy load concentrated at the middle of
the span, has an efficiency of only 11.1 % as compared with a similar volume
subjected to a tensile axial load.

6) The energy of a weight of 100 Kg falling through 50 mm onto a stop at the bottom
end of a vertical bar 40 mm in diameter and 3000 mm long is wholly absorbed
as strain energy. If E = 210 GPa, determine the stress developed in the bar by the
falling weight.

7) The loads to be carried by a lift may be dropped 100 mm onto the floor. The cage
itself weighs 100 Kg and is supported by 24 meters of wire rope, weighing 0.083
Kg/m, consisting of 94 wires, each of 0.158 cm diameter. The maximum stress in
the wire is limited to 900 Kg/cm2 and E for the rope is 74 GPa. Find the maximum
load which can be dropped.
8) The cylinder shown weighs 3000 Kg is released from a height “h” above a spring,
the stiffness of which is 530 KN/mm. If the maximum stress induced in the rod is
630 MPa. Find:
a. The extension in the rod “x”
b. The reduction in the spring length “y”
c. The value of the height “h”
Assume no losses and that the rod is immovable.

9) A load of 890 Kg is being lowered at a steady rate of 600 mm/s at the end of a
steel cable of 625 mm2 section. If the pulley jams when the load is 900 cm
below it, estimate the additional stress induced in the cable by the stoppage,
taking E = 200 GPa. {Neglect the weight of the cable and assume the pulley axis
not to be deflected}.

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