Improved materials characterisation through the application of geometry reconstruction to quasi-static and high-strain-rate tension tests

This paper presents novel materials characterisation techniques for expanding the range of data obtained from tensile tests at quasi-static and high strain rates. Through the application of photography and a geometry reconstruction technique, we obtain data for Steel and Zirconium, with an emphasis on the new opportunities afforded by these techniques. The paper extends the state of the art in tensile characterisation, improving the range of data that can be obtained, and is supported by a number of validation measurements. In particular, calculations of cross-sectional area, shape and ellipticity are presented. These calculations can be performed as functions of both time and axial position. Therefore, it is possible to calculate mean true stress-strain relationships in the material, without the corrections that are required when such relationships are calculated simply using load and displacement data from the ends of the specimen. Steel and Zirconium were selected for their distinct degrees of anisotropy, giving a robust assessment of the capabilities of the techniques. In the future, such measurements will allow researchers to more closely measure, understand, and model, mechanical properties of materials over a wide range of strain rates.

► A high strain rate technique for characterising anisotropic materials is validated.
► The range and variety of data available using the new technique are presented.
► Data include: cross-sectional area, material axes orientation, and R-ratio.
► New data have been obtained for isotropic Steel and anisotropic Zirconium.