Scope:

ASTM D7774 is used to determine the effect of processing, surface condition, stress, and fatigue resistance of plastic material subjected to flexural stress for a large number of cycles. According to this test, a frequency of 5Hz or less is used.

Test Procedure:

The standard test method ASTM D7774 uses a three-point bending fixture and a double-sided loading nose. The dimensions of both sides are identical. The radii of the noses and supports are in accordance with the test method. The fixture has a support span range of 50.8 to 254 mm.

Video 01: ASTM D7774 Flexural fatigue bend fixture for plastic testing

Specimen size:

Test frequency can be 1 – 25 Hz, but it is recommended that a frequency of 5 Hz or less should be used for ASTM D7774 testing.

Data:

For ASTM D7774 testing, the stress level can be determined by the following equation.

Where; Р = load in N,  S = flexural stress in MPa, L = support span in mm

Conclusion:

ASTM D7774 is used to determine the effect of processing, surface condition, stress, and fatigue resistance of plastic material subjected to flexural stress for a large number of cycles.