How do you validate and verify an Izod test result?

Izod tests are widely used to measure the impact resistance of materials, especially plastics and metals. But how do you ensure that your test results are accurate and reliable? In this article, you will learn how to validate and verify an Izod test result using some simple steps and tools.

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1 What is an Izod test?

An Izod test is a type of mechanical testing that involves striking a notched specimen with a pendulum hammer and measuring the energy absorbed by the fracture. The test is performed on a standard machine that has a fixed base, a vertical arm, and a swinging hammer. The specimen is clamped at one end and the notch faces the hammer. The hammer is released from a known height and hits the specimen, breaking it at the notch. The energy absorbed by the fracture is calculated from the difference between the initial and final heights of the hammer.

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Varun Pushpa

PhD student | Metallurgist at South Dakota Mines | Material Science | Process - Friction stir processing/welding, Heat treatment | Material Characterization | SEM/FIB/XRD/Micro XCT |
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The Izod test is a standard impact test used to measure the impact resistance or toughness of a material, especially polymers and other non-metallic materials. This test assesses the amount of energy absorbed by a material when it is struck by a notched, pendulum-type impactor. As the pendulum strikes the notched specimen, it imparts an impact force. The specimen fractures at the location of the notch, absorbing energy in the process. The energy absorbed by the specimen during the impact is measured by the height the pendulum reaches after striking the specimen. The energy is typically reported in units of joules (J).

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2 Why validate and verify an Izod test result?

Validation and verification are important steps to ensure that your Izod test result is consistent, repeatable, and representative of the material's behavior. Validation means checking that the test method and equipment are suitable for the purpose and meet the standards and specifications. Verification means checking that the test result is correct and free from errors and uncertainties. By validating and verifying your Izod test result, you can improve the quality and confidence of your data and analysis.

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Syed Fadzil Syed Mohamed

Fellow of The Institution of Engineers, Malaysia (FIEM)
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Izod impact testing is an important dynamic toughness assessment before component approval. To authenticate the results, I rigorously check specimen measurements, notch sharpness, striker shape, and pendulum integrity against ISO and ASTM standards, replacing any nonconforming parts. I confirm that the test apparatus has recently been calibrated for energy measurement accuracy. For verification, I average at least 5 specimens per sample batch to reduce dispersion while also scanning electron microscopy on the fracture surfaces to ensure the failure mode matches expectations for a properly notched and impacted plastic or composite. This strict process ensures exact, standardised Izod data as a material certification criterion.

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3 How to validate an Izod test result?

To validate an Izod test result, you should follow some best practices and guidelines before, during, and after the test. Start by selecting a suitable test method and standard, such as ASTM D256 or ISO 180, based on the type and shape of your material and the required information. Ensure your testing machine is calibrated and maintained, meeting the specifications of the standard with a valid certificate of verification. Additionally, prepare your specimens according to the standard, making sure they have the correct dimensions, notch geometry, and surface quality. You should also perform the test under controlled conditions with the appropriate procedures for clamping, striking, and measuring. Finally, analyze your test results using the formulas and units specified by the standard to calculate the mean, standard deviation, and coefficient of variation.

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4 How to verify an Izod test result?

To verify an Izod test result, you need to compare your data with some reference values or criteria that indicate the accuracy and reliability of your result. You can do this by comparing your result with the expected or typical values for your material, based on literature, databases, or previous tests. If your result deviates significantly from the expected values, check for possible sources of error or bias in your test method, equipment, or specimens. Additionally, you can compare your result with the results of other tests or methods that measure the same or related properties of your material. Finally, compare your result with the results of other labs or operators that perform the same or similar tests on your material, using interlaboratory comparisons or proficiency testing programs. If any of these comparisons yield significantly different results, investigate potential variations or errors in your test method, equipment, or specimens.

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5 How to improve an Izod test result?

If your Izod test result is not valid or verified, you should take steps to improve it. Review your test method and equipment to ensure they meet the standards and specifications. Make sure the specimens are prepared, stored, and handled correctly according to the standard. Additionally, ensure that test conditions and procedures are controlled, followed, and recorded correctly. Lastly, review your data analysis and calculation to make sure they are accurate, complete, and consistent according to the standard. If necessary, correct or recalculate your data with the appropriate formulas and units.

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6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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How do you validate and verify an Izod test result?

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1 What is an Izod test?

2 Why validate and verify an Izod test result?

3 How to validate an Izod test result?

4 How to verify an Izod test result?

5 How to improve an Izod test result?

6 Here’s what else to consider

Mechanical Testing

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