Development of a Verification Schedule for Deformation Measuring Instruments Used in Uniaxial Tests

The article considers the problem of the lack of traceability of mechanical deformation measurement results to state standards of measurement units and describes a study aimed at developing a verification schedule design. The requirements for metrological characteristics of strain gauges presented in domestic and foreign standards are analyzed. The main methods of standardization of metrological characteristics are defined; their comparative analysis is carried out. The advantages and disadvantages of standardization of metrological characteristics of extensometers defined in ISO 9513 and ASTM E83 are established. A unified approach to the method of expressing permissible error values in units adopted for measuring mechanical deformation is proposed, and the procedure for transferring the unit of deformation to such measuring instruments as extensometers, strain gauges and measuring transducers of deformation is presented. The proposed verification schedule for deformation measuring instruments is important in establishing the metrological traceability of deformation measuring instruments used in uniaxial tests. The work is focused on issues that need to be taken into account when creating a unified system of metrological support for deformation measurements, in particular, the need to introduce a classification of deformation measuring instruments, methods for standardizing metrological characteristics, and methods for transferring units from standards to deformation measuring instruments.