METHOD FOR DETERMINING THE COEFFICIENTS OF STATIC AND SLIPPING FRICTION Russian patent published in 2018 - IPC G01N19/02 

FIELD: testing equipment.

SUBSTANCE: invention relates to the field of mechanical testing of materials, in particular to the determination of the friction coefficient between specimens. One of the specimens, fixed immovably, is made with a working surface having a rectilinear or concave circular shape. Rectilinear guide element is placed at a certain distance from the fixed specimen. Movable specimen is made with two working edges, oppositely located on its diagonal having the length of d. Possibility of moving the movable specimen along the working surface of the fixed specimen is provided. Movable specimen is set so that one of its working edges is in contact with the fixed specimen, and the second, when touching the guide element, is located with such lagging from the first edge in the direction of travel, that a certain angle ϕ is formed between the diagonal of the movable specimen and the perpendicular to the working surface of the fixed specimen or to the line tangential to the circular working surface at the point of contact of the specimens. Load is placed in the middle part of the movable specimen to prevent its movement, and a shifting external force is applied in the immediate vicinity of the edge in contact with the guide element. Experimentally, the position of the movable specimen is found in which, at a minimum distance l from the edge of the movable specimen, in contact with the guide member, to the working surface of the fixed specimen in a direction perpendicular to it or to a line tangential to the circular working surface at the point of contact of the specimens, jamming of the movable specimen occurs and its movement is absent regardless of the magnitude of the shearing force. Distance l is measured and angle ϕ is calculated according to formula ϕ=arccos(l/d). Coefficient of friction between the fixed and movable specimens is determined by formula ƒ=tgϕ.

EFFECT: possibility of determining the coefficients of static and slipping friction by measuring only linear dimensions, without measuring angles and frictional force, at any contact pressures created by a limited external load, to the nature of application of which no stringent requirements are imposed.

4 cl, 3 dwg