flexural test

mechanical testing – flexural test for plastic and composite material

The essence of a flexural test is to determine the flexibility of a material by measuring the force required to bend a beam under a specified loading condition. Typically, a three-point bending condition is used following ASTM D790. 

The sample preparation process for a three-point bend test is relatively simple, as a typical sample is a simple rectangular beam with specified dimensions according to ASTM D790 and ISO 178. The length of the specimen must exceed the distance between the supports and a force is applied to the midpoint of the specimen. Nevertheless, one-point bend test and four-point bend test are also available. 

The three-point bend flexural test employs a simply-supported setup, where the rectangular bar is placed on two supports and deformed by a single central load as illustrated below.

flexural test

There are a variety of standards related to three-point bend test, including ISO 178, ISO 14125, ASTM D672, ASTM D55365, IPC TM-650, and IEC 61189-2:TM20. This test is suitable for plastics and composite materials. Impact uses an Instron universal tester (3382) to carry out flexural testing. In addition, we are also equipped with a special environmental chamber from Instron, which allow us to carry out at sub-ambient or above ambient conditions.

In summary, flexural testing can aid designers & moulders to select the most suitable material for the intended purpose by understanding the following properties:

-Flexural Strength
-Maximum Flexural Stress
-Maximum Strain
-Stress at Strain
-Flexural Secant Modulus of Elasticity
-Flexural Chord Modulus of Elasticity
-Failure Mode and Location


why impact?

Impact Solutions is an independent materials testing and innovative problem-solving provider. Our dynamic team is flexible and adaptable in using their diverse range of knowledge and skills to offer bespoke solutions. Members of impact’s team have over 30 years of polymer experience and are internationally regarded as product and material experts. We can often identify potential sources of weakness in products without even undertaking testing. We will work with you and believe in developing commercially focused and sustainable results for our customers.

Find out more by getting in touch with one of our experts.

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