3 Point Bending Test Method

Flexural Test on Rigid Plastics and Composites Under Impact Conditions

How to Perform a 3 Point Bending Test
The 3 point bending test is a flexural test that is widely used to characterize the mechanical behavior of materials. A small flat beam with rectangular cross-section is placed on a 3 point bend fixture consisting of two parallel supports and the tup insert strikes the specimen in the middle.

The ideal 3 point bending test machine for a  high velocity flexural test is an instrumented drop weight impact testing machine equipped with a 3 point bend fixture and an insert of a given shape attached to the tup.

During the impact, the load is recorded by the sensor (piezoelectric or strain-gauge) embedded in the tup. The load-time curve is then processed to obtain a force-deflection curve. The resulting curve is dependent on the strain rate experienced by the specimen impacted and the drop weight impact testing machine allows to cover a broad range of impact velocity to assess the material performances.

The ASTM D256 and ISO 179-2 Charpy impact test are the main standard methods used to perform fexural bending test, however there are some variants and many customization allowed.