STUDY OF GLASS AND CERAMIC MATERIALS BY ESPI

Electronic speckle pattern interferometry (ESPI) is a very useful tool for investigation of natural vibration of oscillating objects. In contrast to classical measurement by accelerometer, ESPI allows to visualize whole vibrational field of object, and therefore not only to estimate the natural frequency, but also to identify the shape of vibrational mode. Frequencies of natural vibrational modes depend on elastical properties of material, especially on Young modulus E, Poisson ratio μ and density of material ρ. This fact gives us in principle the possibility to estimate the elastic constant of materials from the vibrational measurement. Thin rectangular plates from glass and ceramics were investigated. By aid of electronic speckle pattern interferometry the natural frequencies of various vibrational modes were determined. The method of elastic constant of materials estimation was proposed.