In this paper we describe a method to investigate the interface strength, the process of delamination, and the propagation of cracks in fibre ceramics. Local displacements and displacement fields are determined and evaluated by a combination of the optical measuring procedure UNIDAC (Universal Deformation Analysis by Correlation), digital image processing, and a special equipment for mechanical testing. Digital images of the specimen are recorded under different bending loads and compared by a correlation algorithm. The deformation behaviour of the composite material and of certain components is analyzed under different loads. Further physical and mechanical quantities are then derived from the obtained displacement fields. The displacement fields as well as local displacements can be determined and evaluated for specific layers of the composite material. This method can also be applied to investigate in-situ crack initiation and propagation as well as interface strength and interfacial adhesion. The bending strength and the Young's modulus of materials can be determined. Results of investigations based on a combination of UNIDAC and the 3-point-bending test are shown.