Elastic modulus measurement of quartz glass using digital speckle pattern interferometry based on tensile test

Tensile tests are a standard method to evaluate the elastic modulus by measuring the deformation, usually by an extensometer, at a certain stress within the elastic limit for metal materials. However, this method is rarely used for brittle materials, like quartz glass, because the elastic deformation of brittle materials is several micrometers and is too tiny to be precisely measured by extensometers. Since full-field digital speckle pattern interferometry (DSPI) has a high measurement resolution of tens of nanometers, an elastic modulus measurement method of quartz glass based on tensile testing using DSPI is presented and analyzed. An in-plane displacement optical path of DSPI is set up to obtain the deformation of quartz glass in the tensile test, and then the elastic modulus is calculated. The influence of the tensile load and measurement span on the elastic modulus is analyzed, and the error in fringe direction is corrected. With a reasonable load and measurement span, the experimental results show that the relative error of the elastic modulus can be reduced to 1.18% after error correction.