Impact Testing

Question 1

What is the toughness of metals?

Answer 1

The toughness of metals is the ability to withstand shock load and impact. It will not fracture when twisted.

Question 2

What is impact testing also called?

Answer 2

Also called notched bar or toughness testing

Question 3

What is impact testing used for?

Answer 3

Impact testing is used to calculate the toughness and impact-resistance of materials.

Question 4

What can tough materials withstand?

Answer 4

Tough materials withstand high levels of impacts and shocks without breaking.

Question 5

Name the two types of impact testing.

Answer 5

Izod and Charpy

Question 6

Explain the common principles of operations for both impact tests

Answer 6

A notched bar of the test material is clamped.

A heavy pendulum is released to fracture the bar.

Question 7

Answer the following questions for the Izod test :
Orientation of specimen
Clamp 
Notch 
Strike location 
Energy 
Applications

Answer 7

Orientation of specimen: Vertical (the ‘I’ in ‘Izod’ is vertical).
Clamp: Test specimen is clamped at ONE end.
Notch: Notch faces TOWARDS the hammer/striker.
Strike Location: The hammer strikes the TOP of the notched bar.
Energy: The striking energy is 167 Joules.
Applications: Metals and Plastics

Question 8

Answer the following questions for the Charpy test :
Orientation of specimen: 
Clamp: 
Notch 
Strike location 
Energy 
Applications

Answer 8

Orientation of specimen: The test specimen is HORIZONTAL (the ‘h’ in ‘charpy’ -> ‘horizontal’)
Clamp: Test specimen is clamped at BOTH ends.
Notch: Notch faces AWAY from the hammer/striker
Strike location: The hammer strikes the MIDDLE of the test specimen (opposite the notch).
Energy: The striking energy is 300 Joules.
Applications: Metals

Question 9

Explain the applications for the impact tests.

Answer 9

Applications:
testing of safety products such as crash barriers, car bodies, car suspension systems.
Testing of products that need to withstand high impacts, such as hammers, tools, car wheels

Question 10

What type of hammer/striker can be used during a charpy impact test?

Answer 10

A Pendulum Knife Edge Striker

Question 11

Outline, with sketches, the expected results of impact tests on brittle materials and on tough materials.

Answer 11

Tough material: Expect to be more ductile with more plastic deformation and stretching would be expected at the fracture point.

Brittle material: A brittle material would expect to be broken or snapped straight across at the notch point.