Development of a sensor for surface state measurements using experimental and numerical modal analysis

The characterization of the surface state becomes an increasing necessity for many industries. This paper presents a patented measurement method [M.A. Bueno, S. Fontaine, M. Renner, Dispositif Pour Évaluer L'état de Surface d'un Matériau et Procédé de Mise en œuvre Dudit Dispositif, Patent No. PCT/FR01/01770, 2000], which is able to evaluate the surface state of materials. This method gives roughness-friction criteria and is based on the principle of a tribometer of type “blade-disc”, where the analysed surface is the disc. The sensor is an active element, which vibrates according to its vibrating modes. This work shows how experimental and numerical analysis has allowed optimizing its gage instrumentation and its geometry. Moreover, the modal analysis and the building of a numerical model have set up the coupling between mechanical solicitations of the tested surface and mechanical responses of the sensor in each mode. Finally, an example of measurement of known surfaces is illustrated to explain the results of this study and the efficiency of this measurement method.