Good practice guide for miniature ETMT tests.
This Good Practice Guide discusses various aspects of testing miniaturised testpieces of representative engineering alloys in the NPL / Instron Electro-Thermal Mechanical Test system (ETMT). Different strain measurement techniques are reviewed including the use of electrical resistance, grip displacement and image correlation. Detailed comments are given in respective chapters regarding load calibration and uncertainties in strain, load and temperature measurements. Experiments on reference materials, at room and elevated temperatures were used to compare miniature with macroscopic deformation behaviour. These experiments confirmed that accurate data can be obtained in many circumstances from miniature samples but in some cases there are discrepancies which indicate the need for further metrology studies. Some of these examples are assessed in case studies contributed by NPL, Instron and ETMT users.