Elastic–plastic strain conversion of a thin-plate miniaturized tensile test based on crosshead measurement via an analytical method

This paper underscores the significance of accurate strain measurement in unconventional miniature thin plate specimen (MTPS) tests and proposes a data conversion approach involving an equivalent gauge length (EGL) and a gauge factor (GF). An analytical method is presented to determine EGL for converting elastic–plastic strain data based on the total cross-head deformation of the specimen. The GF values obtained, accounting for various initial geometries of the sample and strain-hardening exponents of the test material, show that, by neglecting elastic elongation, GF only depends on specimen geometries and strain-hardening exponents of the test material, being independent of the applied load, strain rate, and temperature. Validation through Finite Element (FE) simulation and miniaturized tensile tests (MTTs) with digital image correlation (DIC) has demonstrated the sound accuracy of the data conversion method, with the maximum GF errors below 4.82% for selected geometries. The proposed method holds significant implications for the design of MTPS, ductility correction, and comparative analysis of mechanical properties across samples with different dimensions.