Calculation of Measurement Uncertainty for Tensile Strength and Flexural Strength of Thermoplastic

Abstract

In this study, a thermoplastic such as polycarbonate (PC) has been characterized to determine its tensile strength and flexural strength properties. The width and thickness of the PC samples have been measured, and then their average dimensions and standard deviation values were calculated. The samples have been characterized by using a universal testing machine. The tensile strength values of the dumbbell-shaped PC samples were determined according to ASTM D638-10, whereas ASTM D790-10 was applied to ascertain the flexural strength values of the rectangular-shaped PC samples. Based on the obtained results, the average tensile strength value is 58.978±0.258 MPa, whilst the average flexural strength value is 97.437±0.240 MPa. From the measurement uncertainty, the calculated expanded uncertainty for the tensile strength is 0.467 MPa at a confidence level of 95%. On the other hand, the calculated expanded uncertainty for the flexural strength is 0.806 MPa at a confidence level of 95% as well. In summary, the values of expanded uncertainty for the PC samples were particularly influenced by the standard uncertainty values of the tested samples and the expanded uncertainty values of the equipment used.