IMPACT TEST

Significance of Impact test:

            An impact test signifies the toughness of material i.e., ability of material, to absorb energy during plastic deformation. Static tension tests of unnotched specimens do not always reveal the susceptibility of a metal to brittle fracture. This important factor is determined by impact test. Toughness takes into account both the strength and ductility of the material.

           Several engineering materials have to withstand impact or suddenly applied load while in service. Impact strength are generally lower as compared to strength achieved under slowly applied load. Of all kinds of impact tests, the notched bar tests are most extensively used.

Impact tests:

             A pendulum type impact testing machine is generally used for conducting notched bar impact tests. The following type of impact tests are performed on these machines.

    

                  1) IZOD Impact Test                            2) CHARPY Impact Test

IZOD TEST

             The test uses a cantilever test piece of 10 mm X 10 mm section specimen having standard 45 ° notch 2 mm deep. This is broken by means of a swinging pendulum which is allowed to fall from a certain height to cause an impact load on the specimen. The angle rise of the pendulum after rupture of the specimen or energy to rupture the specimen is indicated on the graduated scale by a pointer. The energy required to rupture a specimen is the function of the angle of rise. Fig shows Pendulum type Impact Testing Machine.

Fig shows Pendulum type Impact Testing Machine.