1 Impact test • Many machine parts are subjected to suddenly applied load called impact blows/loads. • An impact test signifies toughness of material, that is ability of a material to withstand impact blow • The capacity of a metal to withstand such blows without fracture is known as an impact resistance or impact strength One must determine: the impact energies the part can be expected to see in its lifetime, the type of impact that will deliver that energy, and then select a material that will resist such impact energy` over the projected life span.
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1
Impact test
• Many machine parts are subjected to suddenly applied
load called impact blows/loads.
• An impact test signifies toughness of material, that is
ability of a material to withstand impact blow
• The capacity of a metal to withstand such blows without
fracture is known as an impact resistance or impact
strength
One must determine:
the impact energies the part can be expected to see in its
lifetime,
the type of impact that will deliver that energy, and then
select a material that will resist such impact energy` over
the projected life span.
2
• There are many types of impact testing machines available
in the market. Following two types are important from the
subject point of view.
1. Charpy testing machine, and
2. Izod testing machine.
Charpy test
The charpy test is carried out on a specimen, which is
55mm x 10mm x 10mm in size and has a 2 mm deep notch
at its centre making an angle of 45°.
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• The specimen is placed horizontally as a simply support
beam between two anvils 40 mm apart in such a way that
the striking hammer strikes the specimen on the face
which is opposite to the notch.
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Izod test
• The Izod test is carried out on a specimen, which is
75mm x10mm x 10mm in size and has a 2mm deep
notch making an angle of 45°.
• The specimen is held vertically as a cantilever
between two jaws, in such a way that the striking
hammer strikes the specimen on the same face as that
of notch.
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Izod test
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• The energy used in rupturing the specimen in both Charpy