Research on the Construction Technology of Self-Monitoring Asphalt Concrete

Combined with the paving of the test section of Self-monitoring Asphalt Concrete, the electrode burying mode of pavement construction is designed according to its characteristics, and the best mixing method and spreading rolling construction technology are compared and analyzed. The results show that the construction structure of the test section is reasonable and feasible, the best mixing effect can be obtained by adding conductive phase material and asphalt at the same time, and the rolling process. The order of rubber wheel and steel wheel compaction has no significant effect on compaction degree.

PROSPECTS FOR STEEL WHEEL TRACTOR DEVELOPMENT WITH HYDRAULIC DRIVE

The article discusses a new scheme for increasing the lateral wheel tractor stability intended for agrotechnical measures, transport and other works complex on mountain and foothill slopes. The proposed scheme of a steeply sloping wheel tractor provides for hydrostatic transmission use instead of a mechanical one, which eliminates the need to install swinging final drives, simplifies the design, and reduces the tractor weight and cost. To ensure the vertical position of the tractor body on a slope, the front and rear drive wheels have an individual hydraulic drive and are mounted on parallelogram suspensions.

A Comparison of 3D and 2D FE Frictional Heating Models for Long and Variable Applications of Railway Tread Brake

The article proposes two 3D and 2D numerical FE models of frictional heating for the estimation of temperature distributions in railway tread brake in 1xBg configuration during repeated long-term braking. The results of computations were compared with the time courses of temperature measured using thermocouples throughout the duration of the tests on a full-scale dynamometer for two different brake shoe materials in combination with a steel wheel. The resulting temperature distributions calculated using the proposed models agreed well with the experimental measurements, and the maximum difference in temperature values does not exceed 20%. It has been proven that 2D FE model can be as efficient as 3D model to estimate the temperature distribution during long-term and variable braking in the considered friction node. The differences in the calculation of the temperature values using these models did not exceed 3%, and the calculation time for the 2D model, compared to the 3D model, was shorter approximately 85 times for the braking cycle lasting 5032 s, and approximately 45 times for the braking cycle lasting 3297 s.

Wear Behavior of Ductile Iron Wheel Material Used for Rail-Transit Vehicles under Dry Sliding Conditions

A ductile iron wheel used for a rail-transit vehicle was treated with a recommended heat-treatment process. The ductile iron wheel after heat treatment was composed of graphite nodules and tempered sorbite with an area fraction of 98%. A friction test of the ductile iron and carbon steel wheel materials was systematically performed under different normal loads and sliding velocities. The results indicated that the wear mechanism of the ductile iron wheel changed from adhesion to abrasion with an increase in the normal load level. Adhesion was the main wear mechanism at different sliding velocities and normal load level. The impact of the normal load on the wear mechanism was greater than that of the sliding velocity. Since the ductile iron wheel material had excellent thermal property and higher carbon content, it exhibited a lower wear rate, a smaller difference value of the friction coefficient, and plastic deformation on the worn surface than those of the carbon steel wheel material. This indicates that ductile iron wheels may have a longer wear life, greater traction, and higher stability during operation than carbon steel wheels. The iron wheels have the potential for being applied in rail-transit vehicles.