Contacts

A. A. Andryushchenko, A. A. Zarifyan, Yu. A. Orlov. Development of Chassis Design for AC Passenger Electric Locomotives: Vl60P/K; Sr1; EP1(M, P) [more] [back]

Objective: to provide an analytical summary of the development of chassis designs for VL60P/K, Sr1, and EP1(M, P) AC passenger electric locomotives equipped with commutator traction motors, and to demonstrate the continuity of technical solutions from the first domestic locomotives to more modern locomotives. Methods: a comparative historical and technical analysis was used, based on both technical documentation and the authors' personal experience. The main mechanical components are examined: body, bogies, body-to-bogie connections, axlebox and body suspension, mechanical traction drive, traction gearboxes, and wheelsets. A comparison is made using axle formulas, traction and braking force transmission methods, traction motor suspension types, and design speeds. Results: it was established that the development of the running gear progressed from the VL60P/K electric locomotive with threeaxle bogies, pintle-type longitudinal force transmission, leaf springs, and a first-class traction drive to the solutions implemented on the Sr1 and EP1(M, P): two-axle bogies, inclined rods, cradle suspension, coil springs with hydraulic dampers, and a second-class traction drive. The role of the Sr1 electric locomotive as an intermediate stage, during which solutions subsequently used on domestic passenger electric locomotives were refined, is demonstrated. Design changes to the wheelsets, gearboxes, and body-bogie connections are summarized. The result was an increase in the design speed from 110 to 140–160 km/h and improved dynamic performance. A unified set of criteria has been developed that allows for the abandonment of solutions that limited speed and increased unsprung mass in favor of more advanced load transfer systems. Practical significance: the article's materials can be used to analyze the evolution of domestic electric locomotive construction over the past 70 years, determine areas for chassis modernization, develop training courses, and formulate requirements for future 1520 mm gauge passenger electric locomotives. It also provides a basis for subsequent comparison with the EP10 and EP20 electric locomotives with asynchronous traction drives. Keywords: AC passenger electric locomotives, chassis, body, bogies, body suspension, axlebox spring suspension, mechanical traction drive, toothed traction reducer, wheel pairs

K. V. Slivetz, V. N. Paramonov. Possible Representation of the Yield Surface and Its Possible Shapes in a Two-Dimensional Problem [more] [back]

Objective: the identification of the shape of the yield surface and analysis of the change in its shape depending on the loading path. The object of research is the basic concept of the theory of plasticity – the loading surface of the material. The subject is the possible representation and shape of the loading surface in a two-dimensional problem. Methods: the article considers a simplified two-dimensional model representing a fragment of a thin-walled pipe. The pipe material is elastic-perfectly plastic material, in accordance with Prandtl diagram. Displacement-Controlled loading for model is assumed. The load is represented by rotation of the pipe cross-section, realized about either a single Cartesian axis or two axes simultaneously. It is shown that load can be considered as a vector. But stress and strain in a point of the body given in term of Tensor Analysis. This issue can be resolved using the Ilyushin representation, according to which a vector is assigned to the deviatoric stress tensor. Results: even for a low level of plastic deformation intensity, the shape and size of the loading surface strongly depend on the loading path. For an isotropic body, this fact can only be explained by the transformation of residual stresses in the body. Practical significance: the proposed approach allows us to apply a simplified mechanical model to the analysis of the transformation of yield surfaces for a wide range of load paths and compare the results with those obtained for real materials. Keywords: yield surface, deformation surface, residual stresses

A. S. Zhevak, D. N. Kurilkin. Mathematical Modeling of the Thermal Stability of Permanent Magnets under External Demagnetizing Fields for Traction Rolling Stock [more] [back]

Objective: to develop a method for assessing the residual life of permanent magnets in traction synchronous motors of locomotives based on Nd–Fe–B alloys, taking into account the temperature dependence of magnetic properties. Methods: the study is based on a thermodynamic analysis of the temperature evolution of magnetic properties using analytical models of the temperature dependence of residual magnetic flux density, incorporating both linear and nonlinear relationships. Results: an analytical model describing the reduction of coercivity in Nd–Fe–B magnets under heating has been derived based on a power-law dependence of magnetocrystalline anisotropy on temperature. A dimensionless thermal stability criterion is introduced, enabling the determination of irreversible demagnetization conditions through the ratio of the operating demagnetizing field to the temperature-dependent coercivity. A method is proposed for converting motor operating conditions into an equivalent demagnetizing field via the d-axis component of the stator current. A comparative analysis of magnets of different commercial grades shows that an increase in energy product is not accompanied by improved thermal stability. An integral measure of degradation accumulation under cyclic heating is also introduced. Practical significance: the results can be used to assess thermal degradation of permanent magnets in traction synchronous motors of locomotives and to predict their residual life under various operating conditions, taking into account accumulated damage. Keywords: permanent magnets, nd-fe-b magnets, magnetocrystalline anisotropy, coercivity, thermal degradation, thermal stability criterion, permanent magnet synchronous motors, locomotive traction motor