In the laboratory, it is important to know which factors may have a bearing on the results of the test. Despite the operator's experience, few operators have a broad understanding of material testing, especially the factors that affect test results, both negative and positive. This is because there are too many variables to consider, and in many cases they vary according to configuration, test material, and type of test. Most factors are difficult to trace, especially in a changing laboratory environment.
        In the question on the test results, understanding these factors contribute to the laboratory and operator to avoid troubleshooting / test and waste a lot of unnecessary testing time and expenses, such as the third party laboratory testing costs. In a QC environment, delay in results may lead to the production of inferior products, and time is usually the most important factor. For R & D and comparative testing laboratories, the number of samples is usually limited and expensive, so no one wants to test it again.
        For laboratory operators and their customers, one of the most adverse effects of changing data is the low credibility of the results. And because uncertainty about the quality of the product, the decision will become very complicated. Do we have to retest? Do I need to make adjustments to the process? Did we do anything wrong? These are all questions that must be answered. The good news is that once you find and understand these factors, it's much easier to get repeatable and accurate results.
        The less obvious factor for the results is the temperature at which the operator holds the specimen. We conducted a study with two operators, one finger "hot" and the other cold". We find that for some materials, there is a clear difference between the maximum strain and the yield stress.
        In addition, we found that the time of holding samples before test may also lead to change. The corresponding solutions include wearing gloves and using more efficient attachments to shorten holding times, such as pneumatic jigs, integrated sample measurement devices, or fully automated solutions.
        All of these factors have simple and effective solutions, from sample centering devices to automated operations, adding preload in the method, and integrating visual tools, which can provide guidance to operators during testing.

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