ISO 14125 Flexural Properties of Fiber-Reinforced Plastic Composites

ISO 14125 is a test method to determine flexure properties of fiber-reinforced plastic composites. There are two methods used, Method A for a three-point flexure test and Method B for a four-point flexure test. There are four material classes, Class I – IV, which define the specimen length, span, width, and thickness. The standard requires deflection measurement not exceed +/- 1% error of full scale. The 2810-400 bend fixture is fully compliant with these requirements.

The challenges of testing to this standard:

• Flexural strain measurement
• Repeatability of calculations
• Reporting calculations in compliance with the standard

Our solution:

• Flexural strain measurement – There are two methods for reporting strain that are compliant with ISO 14125: a clip-on extensometer attached to a deflectometer plunger, or the AutoX - both options offer the accuracy to measure flexural modulus.
• Repeatability of calculations – When setting up the test, having an adequate preload is highly recommended to ensure accurate and consistent strain measurements. How much force is applied to the specimen prior to starting the test directly impacts the repeatability of calculations such as flexural modulus. Alternatively, a slack correction, also referred to as a tow compensation, can be used to ensure that the calculations are performed on the appropriate section of the testing data.
• Reporting calculations in compliance with the standard – Bluehill Universal testing software has advanced pre-built methods available with pre-configured plastic specific calculations helping to ensure compliance.

For labs with a high volume of testing, Instron^® offers a 6-axis robotic system (AT6), and non-robotic 3-axis system (AT3).

It is important to review ISO 14125 in order to fully understand the test setup, procedure, and results requirements.