Test Procedure:

Most commonly the specimen lies on a support span and the load is applied to the center by the loading nose producing three point bending at a specified rate. The parameters for this test are the support span, the speed of the loading, and the maximum deflection for the test. These parameters are based on the test specimen thickness and are defined differently by ASTM and ISO. For ASTM D790, the test is stopped when the specimen reaches 5% deflection or the specimen breaks before 5%. For ISO 178, the test is stopped when the specimen breaks. Of the specimen does not break, the test is continued as far a possible and the stress at 3.5% (conventional deflection) is reported.

  



Die cut, saw, or injection mold your samples to a shape specified in the ISO/ASTM Specification.
If you have a standard shape then you do not need to enter the depth, width, and span length for each test.
If you have specimens that vary in width and depth then you will need to adjust the span length for each test as well as enter in the new width, depth, and span length as these values are used in the calculations.
Place the test bar on the 3 point bend fixture and begin the test and end after bending to 5% deflection or until the sample breaks.

Specimen size:
A variety of specimen shapes can be used for this test, but the most commonly used specimen size for ASTM is 3.2mm x 12.7mm x 125mm (0.125" x 0.5" x 5.0") and for ISO is 10mm x 4mm x 80mm.

Data:
Flexural stress at yield, flexural strain at yield, flexural stress at break, flexural strain at break, flexural stress at 3.5% (ISO) or 5.0% (ASTM) deflection, flexural modulus. Stress/Strain curves and raw data can be provided.

Standard:
ISO178, ASTM D790, JIS K7171, GB/T 9341 etc.,

Equipment Used:
electronic universal testing machine,
bending test fixtures