Materials must balance strength, durability, weight, manufacturability and cost. Yet, as materials evolve, the way they are tested must evolve alongside them. Fabio Lipari, materials engineer at materials testing instrumentation manufacturer Instron, explains how to select and apply the right materials tests to suit your application.
In recent years, materials engineers have faced a familiar but increasingly complex challenge: materials must do more, in more demanding applications, but with less margin for error. Selecting the wrong test method, or applying the right test in the wrong way, can lead to misleading results, expensive redesigns and, in extreme cases, real-world failures.
Materials testing sits at the intersection of development, production and quality control (QC). During R&D, engineers rely on testing to understand how a material behaves, how it responds to stress and how changes in formulation or processing affect performance. Later, in QC laboratories, testing becomes a gatekeeper – confirming that each batch meets the properties promised on the technical data sheet and behaves consistently over time.
Materials testing challenges
In both R&D and QC applications, impact testing is often central, particularly for polymer-based materials that must withstand drops or sudden loads in service. However, engineers must recognise that impact resistance is not a single, universal property. Different tests measure different aspects of material behaviour, under different conditions, and with very different levels of detail.
Simpler methods, such as pendulum impact tests, provide a single value that is easy to compare and ideal for high-throughput QC. Whereas advanced approaches, such as instrumented drop tower testing, generate rich datasets that reveal how force, displacement and energy evolve throughout the impact event.
Problems arise when tests are selected out of habit rather than intent. Engineers often apply a familiar standard without fully considering whether it reflects the real-world scenario they are trying to simulate.
Small deviations can have large consequences. Changing specimen dimensions, using the wrong impact energy or applying a standard written for a different class of material can all distort results. For polymers in particular, factors such as notch sensitivity, temperature and sample preparation play a critical role in determining whether a material behaves in a ductile or brittle manner under impact.
Misunderstanding impact behaviour has consequences across the value chain. For example, a raw material producer may provide an impact resistance value that later proves unachievable in practice, leading to disputes. Or, a manufacturer may discover late in development that a material does not perform as expected, forcing expensive redesigns or production delays. Even during QC, unexpected results can halt production entirely while the root cause is investigated.
Instron 9050 impact pendulum tester
Informed materials test selection
Materials test selection should always be about choosing the right test for the job, not simply picking the test you are most familiar with. Test methods must align with material type, application and developmental stage.
For routine QC, pendulum impact testing remains a fast, robust and standardised solution, particularly when comparing results directly against datasheet values. For R&D and advanced applications, instrumented testing offers deeper insight, enabling engineers to understand how and why a sample has failed under test.
Equally important is everything that happens before testing. Sample preparation, especially notching, must be performed with precision and consistency. Even the method used to create a notch, whether by cutting or milling, can influence local material properties and, ultimately, test results.
Impact energy selection is another critical factor. Using a hammer that is too energetic may mask differences between materials, while too little energy can produce inconclusive data.
As new materials continue to emerge, engineers will increasingly find themselves testing outside established standards. In these cases, building a meaningful correlation between test results and real-world performance is critical. That requires careful parameter selection, a clear understanding of limitations and collaboration between testing experts, like Instron, and material developers.
Ultimately, the right test is the one that answers the right question. By thinking first about the final application, the expected loading conditions and the decisions that will be made based on the data, engineers can ensure that material testing remains a powerful tool rather than a potential source of uncertainty.
For further information on materials testing instrumentation, visit Instron’s website.
For more Materials news: https://designsolutionsmag.co.uk/category/materials-in-design-prototyping/
