ISO 178

ISO 178

ISO 178 is a three-point bend test where a force is applied on the midpoint of a sample, which is supported at either end.

    ISO 178 Testing Standard

    ISO 178 is a three-point bend testing procedure used to test the flexural property of semi-rigid and rigid plastic on a universal testing system. 

    The test sample is placed on two parallel anvils and bent using a compression die without breaking the piece. The applied force is measured via a load cell, and the deflection is measured either by a direct strain measurement device or the system’s crosshead displacement. The specimen’s thickness is a function of the span of the three-point bend fixture. 

    The ISO 178 test is stopped if the specimen breaks. If the specimen does not break, the test is continued and the stress at 3.5% (conventional deflection) is reported. 

    A variety of sample shapes can be used for this test but generally, a sample with dimensions – 10 mm* 4 mm* 80 mm is used. This method is usually used for determining the flexural modulus, flexural strength, and flexural strain/stress relationship under defined conditions.

    Image 01: Three-point bend test setup for plastics as per ASTM D790

    The method is suitable for:

    • Thermosetting molding material, including reinforced and filled compounds
    • Thermosetting sheets
    • Thermoplastic mold casting and extrusion material, including reinforced and filled compounds 
    • Rigid thermoplastic sheet

    Common Uses of ISO 178 testing

    • Determine flexural properties of rigid and semi-rigid plastic
    • Determine flexural properties of polymers

    Advantages of ISO 178 testing

    • Sample preparation is easy 
    • As compared to the tension test, gripping of sample is easy

    Limitation of ISO 178 testing

    • It is a destructive test
    • Displacement range and force applied are limited 
    • Different test environments require different specialized equipment accessories 

    Industrial Application of ISO 178 testing

    • Aerodynamics 
    • Plastic and polymer industry

    Core Materials Testing Services


    A variety of microscopy and spectroscopy tools available for precise measurements from the nano to the meter scale.

    Metrology Testing Services POPULAR TESTS:

    TEM SIMS Profilometry

    Materials Testing

    ASTM and ISO standard and custom chemical, mechanical, thermal, corrosion tests, etc. for all materials metals, ceramic or polymers.

    Materials Testing Services POPULAR TESTS:

    Nondestructive Testing Electrical Testing Chemistry Analysis

    Product Testing

    Thousands of tests for product quality and reliability under heat, humidity, temperature shock, vibration, drop, electrostatic discharge.

    Product Testing Services POPULAR TESTS:

    Vibration Testing Humidity Testing Accelerated Aging

    Looking for Material Testing?

    We have already delivered 10000+ Material Test results to top companies

      Send us a request

        Process for testing

          STEP 01

          You share material and testing requirements with us


          STEP 02

          We ensure your sample pick-up in an ensured manner


          STEP 03

          We deliver test report to your inbox

          Let’s work together!

          Share your testing requirements with us and we will be happy to assist you.

          ddd Just share your testing requirements and leave the rest on us!
          • Free, no-obligation consultation
          • Guaranteed confidentiality
          • Quick turnaround time
          • Hassle-free process


            Let us combine our capabilities to achieve success!!

              idea icon
              Want to connect with an expert before you leave?