ADVANCED MATERIALS & PROCESSES | JANUARY 2026 31 elasticity, allowing for greater visibility of key data points during testing when compared to less elastic samples (Figs. 3 and 4). This visibility is more apparent along graphical representations of the load application. The initial observation of the application of load may not indicate creep—rather, creep begins with load application to a target load value, and then sustaining that value while other testing conditions are kept constant. After achieving this point, the load will taper off, and the creep rate will be kept uniform, and the stress in the sample will remain relatively constant while the elongation increases, or the elongation will remain constant while the stress decreases. DATA COLLECTION To enable the collection of data, material measurement equipment will often include an extensometer, partic- ularly with tensile testing (Fig. 5). When determining elongation, the addition of an extensometer will enable consistent, repeatable baseline values for the gauge length of the starting sample. Fig. 5 — Full view of the Starrett MMS-5000 test stand with built-in extensometer. The test being performed uses extensometer readings of the ethylene propylene diene monomer (EPDM) rubber band as it is being elongated using metal hook fixtures. This allows the extensometer to perform the elongation measurements. This means the technician will not need to rely on encoder measurements that may not accurately reflect the elongation if the initial separation is not properly measured. Using an exten- someter, samples will have a fixed starting gage length at the beginning of the test, and will allow precise, consistent measuring. Depending on the model of the extensometer, they could be built in-line with the test stand such as with the Starrett extensometers, or they could be independent measuring devices. The difference between them is that the independent unit can be removed and disengaged at any point, whereas the built-in units are typically designed for running tests against the entire length of the machine’s travel. ~AM&P Note: All images courtesy of the L.S. Starrett Company. For more information: The L.S. Starrett Company, 949.348.1213, support@kine- metric.com, www.starrettmetrology.com. Are you maximizing your ASM membership? Expand your knowledge and apply your ASM International member-only discounts to a variety of professional development resources: • AM&P Digital Edition • ASM Archive • Discounts on event registration Learn more about your membership benefits by visiting asminternational.org/membership
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