Determination of elastic constants for particleboard using ultrasound

In this study, effects of moisture content on elastic properties of particleboards that are mainly used by furniture industry in Turkey were investigated. These properties are particularly important in the engineering analysis of furniture systems constructed with these materials. The properties which determined are; Young modulus (Ex, Ey, Ez), Poisson ratios (?xy, ?xz, ?yx, ?yz, ?zx, ?zy) and shear modulus (Gxy, Gxz, Gyz). The sample boards of the study were randomly selected from only one of three different commercially manufacturers. Test samples which are 20 x 20 x 30 mm and 20 x 20 x 60 mm in size were prepared from the outer and inner layers of the boards were conditioned at temperature of 21?C and 35 %, 45 %, 55 %, 65 % and 75 % RH. The density and moisture content of the samples were determined and exposed to compression tests in order to obtain stress-strain diagrams. The elastic properties and compression strength of the samples tested were calculated using stress ? strain diagrams. Elastic properties of the board layers are also significantly different. The average Young modulus in face layer of the particleboards tested by ultrasonic method in x direction 3167 N/mm2, in y direction 2958 N/mm2 and in z direction 555 N/mm2. ?n x direction 1205 N/mm2, in y direction 954 N/mm2 and in z direction 156 N/mm2 in core layer. The average shear modulus in the face layer in xy direction 1477 N/mm2, in xz direction 657 N/mm2, in yz direction 629 N/mm2. in xy direction 613 N/mm2, in xz direction 217 N/mm2, in yz direction 187 N/mm2 in core layer. The average Poisson's ratio in face layer 0.42 and in core layer 0.65. In general, moisture content has more profound effect on the Young modulus than other elastic properties. Results obtained can be used in modelling the orthotropic behavior of elements or systems which are constructed using particleboard under loads.