Fedosov-Nikonov D. Improvement of strength qualities of long-wheelbase cars platforms by improvement of their designs and methods of calculations

The thesis is devoted to the topical issue of improving the strength characteristics of long-wheelbase platform cars. To select promising design solutions and determination of rational parameters of modern flat cars made classification wagons-platforms for transportation of containers for the purpose of the analysis of world experience of production of platforms. Reviewed the structural performance of the frame elements modern flat cars. Measures to reduce the stress concentration factor in the structural elements to be taken into account in the production of long-wheelbase platforms are considered. The analysis of damages of long-wheelbase platforms is carried out. The factors that significantly affect the structural strength of the long-wheelbase platform are established. A procedure for assessing stresses in the frame of a long-wheelbase platform car depending on different types of payloads (containers, pipes, etc.) has been developed and a method of a refined assessment of the fatigue resistance reserve factor depending on the structural version of the long-wheelbase platform frame has been developed. The mathematical model of the stress-strain state of the car-platform in part of the formation of the calculated loads depending on the disturbances from the path, which allows to increase the reliability of the determination of stresses in the elements of the load-bearing structure of the long-wheelbase platform, has been improved. An improved mathematical model of the platform spatial oscillations, which, unlike the existing models, allows to evaluate strength properties together with dynamic parameters. Theoretically, the expediency of the proposed technical solutions for improving the design of the long-wheelbase platform car and structural changes that reduce the stress-strain state of the elements of the long-wheelbase platform car and improve its strength characteristics is confirmed. Conformity assessment of construction of the frame of the carriage requirements "Standards ..."I and III modes, impact mode and repair modes was carried out by way of the comparison of the calculated equivalent stresses with the allowable ve-masks in accordance with the "Standards...". A specific stress-strain state of frame car for I and III, re-presses, regime collisions, and the repair modes pcimci two jacks. The values of equivalent stresses obtained during calculation and static tests are given. In the fourth section, the calculation of the frame elements on the second for the case of the maximum permissible loads in sections with a high level of alternating stresses. Static stresses from the weight of the bruto wagon were obtained from the finite element calculation using ANSYS software. The calculation is carried out according to four variants of loading, at which we have the greatest bending moment, determined in terms of strength. A certain stress-strain state of the car from the action of the gross weight force and the fatigue resistance factor in the areas in which the fracture occurred during the bench tests. When carrying out bench tests of fracture were detected in two areas: in the section I-I in the area of termination pads and in the section III-III ridge of javorníky-two beams at the slits for a horizontal lever brakes. A certain stress-strain state of these zones when loaded with two 40-foot containers. The calculation results are presented. The values obtained coefc-NTA stock fatigue resistance is less valid [n] = a 1.5. Strengthening of zones of destruction is carried out. For the fracture zone in the section I-I, an overlay on the lower belt was removed, which allowed to reduce the stress concentration near the seam and reduce the concentration coefficient from 5.0 to 2.5. For the fracture zone along the window in the section III-III, the transfer of the butt joint of the reinforcing rim to the zone with lower voltages was carried out, which allows to reduce the stress level from 66.1 MPa to 5.1 MPa. The calculation of fracture zones for fatigue resistance is carried out. Positive results were obtained Analysis of the results of experimental studies and their satisfactory convergence with the results of theoretical studies indicate the adequacy of mathematical models of the stress-strain state and spatial oscillations of the platform.