A flexometer test measures the developing heat inside a rubber material due to a cyclic compression. Heat increase inside the rubber material can cause complete internal degradation, which would be dangerous for, e.g., tire treads.
Usually, the test is performed with 30 Hz and a static load of 1 MPa, followed by a dynamic stroke of 4.45 mm. This test is called the Heat-Build-Up (HBU) test. If the static load is raised to 2 MPa, the test is known as a blow-out (BO) test.
The measuring methods are also included in the ASTM-, DIN- and ISO- Standards, e.g., ISO 4666: Rubber, vulcanized-determination of temperature rise and resistance to fatigue in flexometer testing.