This paper is devoted to glass/alumina materials which can exhibit important damages at the interface in the case of a difference of the coefficients of thermal expansion between the matrix and the inclusions. One of the key-issue for this type of materials use is to determine and quantify this damage. This paper presents numerical and experimental approaches for this purpose. A numerical model is used and coupled to a homogenization procedure to evaluate damages provoked by the difference of the coefficients of thermal expansion. Cohesive elements have been introduced in the FE model so as to simulate the interface damage. Some thermal tests have been done on two-phase specimens. Experimental and numerical results are compared and analyzed.