Determination of strains of thin wood samples using videoextensometry

In this work the use of an optical measurement system applied to the mechan ical characterization of thin microtome sections of spruce (Picea abies Kar st.) is shown. This measurement system is contact-free and allows the measu rement: of strains in two orthogonal directions simultaneously and in realt ime. The capability of the measurement system is compared with other measur ement arrangements (DMS, Image correlation technique, holography, Moire tec hnique) in regard to the special. efforts of its application to wood. Moreo ver, from the measured strains and stress modulus of elasticity (grain dire ction), tensile strength and Poisson's ratio of earlywood and latewood were determined separately.