Summary of Test
ASTM D790 is one of the most commonly used specifications in the plastics industry. This test measures the flexural strength and flexural modulus of reinforced and unreinforced plastics. These calculations relate to the stiffness of your material and allow you to choose materials that do not bend when supporting the loads you require for your application. The test uses a universal testing machine and a three point bend fixture to bend plastic test bars to acquire the data needed to make the calculations.
Prior to conducting ASTM D790, it is important to read the entire specification in the relevant ASTM publication.
Recommended Equipment
Testing Procedure
To run the test, begin by die cutting, sawing, or injection molding your samples to a shape specified in the ASTM specification.
- Adjust the support span length that you find in the standard determined by your sample size.
- Place the test bar on the 3 point bend fixture and begin the test at the rate specified in the standard.
- The test will conclude at the deflection point specified in the standard, or when the sample breaks.
Tips
- Testing speed: The speed of the test is very slow and variable depending on the support span and depth of beam which are used in the calculation used to determine the speed.
- Use a standard size test bar if possible! In tensile tests that have samples that are always different sizes all you have to do is enter the width, thickness, and gauge length of a sample. However, for D790, variable specimen sizes are more burdensome because not only do you need to enter the specimen size, but you also need to adjust the 3 point bend span length and the speed of test. A standard size allows you to run multiple tests without having to change these parameters.
Just Ask!
Questions about running ASTM D790 on your system?
