Estimation of the bearing capacity of a threaded pair made of needle-punched frame/pyrocarbon matrix-based carbon-carbon composite materials

Thu, 15 Oct 2026 00:00:00 +0400

The paper describes experimental investigation of the bearing capacity of threaded fasteners made of carbon-carbon composite materials based on a needle-punched frame and a pyrocarbon matrix. The bearing capacity of a single-screw threaded pair under normal as well as extreme temperatures was estimated. The strain diagrams were obtained and processed. In the experiment simulating loading on one turn of a threaded joint, dependence of the shear strength of the material depending on the shear area size was studied. The scale effect influence on the shear strength of the material was determined. The results obtained were compared to those obtained for threaded fasteners made of spatially reinforced carbon-carbon composite materials.
EDN: KULPPZ, https://elibrary/kulppz

Experimental determination of the friction force in a low-speed, long-stroke, grease-free stage

Mon, 19 Oct 2026 00:00:00 +0400

It is determined that the mechanical losses in the slow-speed stage, despite the large pressure drop (? = 100), are less than the mechanical losses in high-speed compressors. It is recommended to take the power spent on overcoming the friction forces in the sleeve cylinder piston seal equal to 10–15 % of the indicator power of the stage. Since there is only one friction unit in the low-speed stage, the power required to overcome mechanical friction is equal to the power expended to overcome the friction forces in the sleeve cylinder piston seal. The mechanical efficiency of the slow-speed stage is in the range of 0.89–0.92, which corresponds to the mechanical efficiency of high-performance gas engine compressors having a common shaft with a drive. The total isothermal efficiency of a low-speed long-stroke stage lies in the range of 0.50–0.95, while for high-speed compressors the total isothermal efficiency lies in the range of 0.60–0.75. The friction force caused by the forces of the material’s own elasticity and expander pressure was also determined for various cylinder diameters.
EDN: VSACVC, https://elibrary/vsacvc

Mechanical Engineering and Machine Science. Vestnik MGTU

Estimation of the bearing capacity of a threaded pair made of needle-punched frame/pyrocarbon matrix-based carbon-carbon composite materials

Experimental determination of the friction force in a low-speed, long-stroke, grease-free stage