Vol 36, No 1 (2016)

Experimental results for the drag torque on a high-speed caterpillar vehicle entering a turn are compared with the drag torques determined by existing methods for steady curvilinear motion. Nikitin’s model proves applicable not only for steady turns but also as the trajectory changes on entering a turn.

The operational risk in technological systems may be assessed on the basis of the theoretical probability distribution of possible faults with consequences of differing severity.

The distribution of the number of loading cycles to failure is considered. To that end, experimental data on sample deformation in low-cycle loading with specified loads are analyzed by means of nonparametric statistics.

The elastic properties of composites (the Young’s modulus, Poisson’s ratio, Lame constant, and shear elastic modulus) are determined in model calculations, when the variation in concentration of the components is taken into account.

Polymer coatings may be used in tight joints to prevent fretting corrosion. The constraint on their use is the polymer adhesion with the metal. A method of calculating the life of such joints is presented.

Modification of Babbitt coatings by carbon nanotubes in plasma–powder application is considered. A model is proposed for the interaction of a graphene-like surface and atoms from the Babbitt alloy. The influence of carbon nanotubes obtained by different means on the performance of antifrictional coatings is studied.

A thermomechanical model of the resistance of titanium alloys to cutting is proposed. The model takes account of the influence of the strain, strain rate, and temperature on the yield point. The maximum yield point in the chip-formation zone and at the front surface of the cutter is established. Analysis of elementary-chip formation in the turning of titanium alloys permits the determination of the temperature and cutting force.

The physics of grinding is considered in order to explain the difference in machinability of tungstenfree and tungsten steels. The strength of the most common steels and alloys is studied over a broad range of strain rate and temperature. Analysis of the results established the variation in strength of high-speed tungsten-free and tungsten steels in typical grinding conditions and permits explanation of the difference in machinability of the steels in physical terms. The relation between the machinability of steel and wear of the abrasive tool is investigated in experiments with individual grains (plane angle ϕ = 90°) of different abrasive materials: electrocorundum (24A), zirconium corundum (38A), and Elbor (Borazon). That permits the derivation of a regression equation reflecting the qualitative characteristics of the process, such as the starting point, the presence of an extremum, and the asymptotic behavior.

An effective method of machining the geometrically complex surfaces of compressor blades in gas-turbine engines is considered (creep-feed grinding). This method is widely used in the machining of hard materials such as high-temperature nickel alloys and cobalt alloys employed in the manufacture of gas-turbine components.