Micro-mechanical properties of the Song Dynasty stone tiles based on nanoindentation tests and homogenization approach

Abstract

The Song Dynasty stone tiles are one of the representatives of ancient Chinese building materials and reflect the technical level and the aesthetic concept of architecture in the Song Dynasty. Studying the mechanical properties of the Song Dynasty stone tiles is a great significance to design and develop restoration materials. The stone cultural relics are different from modern buildings, because of their particularity, cultural relics protection should preserve their original historical features as much as possible. It is a challenge to sample and perform traditional tests, which require numerous large specimens. The nanoindentation technique and the homogenization calculation method based on the Mori-Tanaka model were proposed to calculate the mechanical parameters of the Song Dynasty stone tiles. With the help of X-ray diffraction (XRD) and scanning electron microscope (SEM), the indentation morphology and mineral composition in indentation area were quantitatively analyzed. The mechanical properties, such as elastic modulus, hardness and fracture toughness of the Song Dynasty stone tiles in Henan, China, were investigated by nanoindentation test. The homogenization approach based on the Mori-Tanaka model was developed to upscale mechanical parameters from micro-scale to meso-scale, which were further compared with uniaxial compression results of non-standard samples. The results show that there is a positive linear correlation between elastic modulus, hardness and the fracture toughness under micro-scale. The average elastic modulus of red stone tiles and green stone tiles are 29.47GPa and 30.21GPa respectively. Compared with the parameter results obtained by upscaling, the deviation rates are 10.3% and 9.6%, respectively. The mechanical parameters of the Song Dynasty stone tiles obtained by nanoindentation test and homogenization approach is reliable.The proposed methods in this work provide the basis and reference for obtaining the mechanical strength index of the Song Dynasty stone tiles.