Determination of the friction coefficients of chestnut (Castanea sativa Mill.) sawn timber

This work provides the values of both the static and the kinetic friction coefficients for chestnut (Castanea sativa Mill.) of Spanish origin. Knowledge concerning these coefficients has its main application in the study of agroindustrial structures and machinery with timber members in contact. This determination was developed taking into account the timber anisotropy to establish surfaces and directions of slipping. A modified direct shear test device was used to conduct the tests and reproduce the tribological system. This procedure was functional and reliable and considered suitable for standardizing the friction measurement between timber surfaces, since this device is widely distributed in geotechnical and materials laboratories and the European codes do not specify a procedure or device to carry it out. The average values obtained were 0.46 for the static coefficient and 0.33 for the kinetic one, without considering the surfaces and directions of slipping. These values ranged between 0.36 and 0.55 for the static friction coefficient and between 0.28 and 0.39 for the kinetic friction coefficient depending on the direction considered and also taking into account the anisotropy of the timber. A good correlation was obtained between both coefficients, thus allowing for the estimation of the kinetic coefficient from the static one.