ASTM D1822 Tensile Impact Test for Plastics

Scope:

Impact tensile strength is the ability to withstand forces due to sudden tensile loading. It is relevant for many industrial applications of plastics such as pipes, electrical insulation on cables, packaging, building construction, and transportation, where components are prone to damage by events such as collision or dropped objects The ASTM D1822 test method involves subjecting two types of specified specimens to tensile impulse forces generated by a swinging pendulum and anvil system. The test sample, which is clamped into the swinging pendulum, experiences tensile rupture force when the swinging pendulum is brought to a sudden stop by the anvil. The energy that causes the specimen to rupture in a single swing of the pendulum is reported as the Tensile Impact Energy. The ASTM D1822 test is applicable to rigid as well as flexible plastic and electrical insulating materials.

Test Procedure:

Dumbbell-shaped test specimens are first prepared using the test plastic material. The ASTM D1822 test is performed using two types of specimens, one denoted by S (short) and the other as L(long) specimens, indicating shorter and longer reference gauge lengths, respectively.  The test apparatus uses a swinging pendulum with a hammer as the kinetic energy source and an anvil arrangement for momentum transfer.

One end of the test specimen is clamped into the pendulum hammer while the other end is fixed to a yoke that swings along with the sample. The pendulum hammer, specimen and yoke assembly is propelled at high speed toward the anvil. Upon striking the anvil, the hammer comes to rest, but the momentum of the moving yoke exerts tensile stress on the plastic specimen. At rupture energy, the yoke together with the broken piece detaches from the hammer end of the specimen. Type S specimens, having shorter initial lengths, exhibit low extension and tend to produce brittle fractures. The longer Type L specimens can stretch more before rupture. The test can be conducted over a range of temperatures that are of interest.

Specimen size:

Specimen length for both S and L types is 63.5 mm. The type L specimens have a gauge length of 9.53 mm while the S type specimens do not have a true gauge length.

Data:

The rupture energy is expressed in kilojoules (kJ) or kJ/m² .

Conclusion:

The ASTM D1822 test method covers the determination of the energy required to rupture standard tension-impact specimens of plastic materials.