Numerical estimation of using possibility of porous GFRP sliding bearing as part of a caterpillar mover bottom track roller

Currently, antifriction bushings for sliding bearings made of expensive non-ferrous metal alloys are used in low-speed caterpillar track rollers. Composite bushings based on porous GFRP obtained by radial winding is a cheap alternative for metal ones. They can withstand high radial compressive loads and successfully work without lubrication supply system using only self-lubricating modifiers in their open porosity. The bushings have a low stiffness in the radial direction due to the porous structure. Low stiffness contributes to the formation of a significant contact area between interacting surfaces. Low contact normal and tangential stresses lead to a shaft wear reduction. Low interlaminar strength is the main factor limiting the use of composite bushings. Determination of the maximum radial and shear stresses emerging in the operational process of a friction unit is a very important problem. First part of the work is devoted to determination of the static and sliding friction coefficients for composite bushing. Combination of static tests up to fracture and numerical analysis was used to determine the critical interlayer shear stress. In the second part of the work, numerical model of a support roller with antifriction bushing was developed. This model was used to determine the stress-strain state of antifriction bushings of the support roller of pipe-laying machine TR-20. Distribution of normal stresses on the contact surface with the shaft for GFRP and bronze bushings were found. The relations between the maximum normal stress value and the radial clearance in pair “shaft-bushings” were obtained for both types of bushings. It was shown, that the value of the local normal stresses is significantly affected by the skew-symmetry of the roller support, clearance in pair “shaft-bushings” after assembly and after exploitation. The maximum reasonable value of the radial clearance between the shaft and the bronze and GFRP bushings were 0.25 mm and 1 mm respectively. The use of antifriction composite bushings allows increasing the value of the maximum permissible clearance of friction unit more than two times in comparison with metal one. The paper shows the possibility of replacing antifriction bronze bushings on porous GFRP bushings.