Identification of asymmetric constitutive laws at high temperature based on Digital Image Correlation

The mechanical characterization of ceramics can be very challenging. Depending on their composition and fabrication process, ceramic materials may exhibit at room temperature different types of mechanical behaviours, ranging from linear elastic to quasi-brittle, like rocks, concrete or plasters. At elevated temperature, they may present a non-linear behaviour, due for instance to the presence of a vitreous phase. However, estimating the evolution of their behaviour from room temperature to elevated temperature is a challenging topic, especially when there is an asymmetry between tension and compression. A methodology based on Digital Image Correlation is presented in this paper where four point bending tests are analysed for temperatures ranging from 25 °C to 900 °C. For a ceramic mainly made of aluminium titanate, the evolution of an asymmetric constitutive law is identified with a strong link with microstructural observations using SEM images.