This work is treated in the framework of CUBISM project funded by INTERREG V program. The purpose of the project is to develop a pressure and humidity SAW sensor, in order to follow the drying of refractory materials under high temperature and pressure conditions. More precisely, we aim to describe and predict the thermo-mechanical behavior of the piezoelectric SAW substrate under such conditions for a full set of geometrical configurations and materials. Besides, we expect to take into account the micro-cracks resulting from thermal expansion mismatch between the substrate and its environment. However, at the microscopic scale, the finite element method is less suitable to describe discontinuities induced by micro-cracks. For that reason, we propose to study the thermo-mechanical behavior using the discrete elements method (DEM). This choice is also motivated by the advantage of DEM to describe the crack propagation. This contribution presents significant improvement for DEM to model the 3D thermal-induced damage due to thermal expansion. Furthermore, this study allows to follow the damage level of the material during its lifetime. Thanks to the MULTICOR3D++ code developed in our laboratory, a hybrid particulate-lattice model [1], based on the equivalence between a granular system and a network of cohesive beam elements, is generated. Our contribution is to introduce the linear thermal expansion at the scale of the contact by modifying the initial free length of each link, using the model introduced in 2D by [2]. Heat transfer by conduction is taken into account, what requires contact areas which can be computed using two approaches. The first one consists in calibrating a coefficient describing the mean ratio between particle and contact areas. The second one is to associate a polyhedral element to each particle, using the concept of representative elements. Besides, we study the characteristics of materials in terms of the number of discrete elements, also the equivalent stress and strain of each particle are determined using a representative area. In addition, a model of damage resulting from thermal expansion was introduced. We consider that the fracture occurs when the hydrostatic stress for local tensile solicitations is greater than a given tensile strength limit. [1] H. Haddad. Modélisation du comportement thermomécanique de l’interface de contact par une approche couplée MED-MEF. PhD thesis, France, 2013. [2]W. Leclerc, H. Haddad, M. Guessasma. On a Discrete Element Method to simulate thermal-induced damage in 2D composite materials, In Computers & amp;amp;amp;amp;amp;amp;amp;amp;amp; Structures, 2017, ISSN 0045-7949.