“…Harder 22 developed a specific element in the ADAMS platform for simulation of a specific type of wedge design, which provided a constant friction damping regardless of loading. Ballew 23 studied the effects of geometry and inertial properties of friction wedges on dynamic responses of a four-degreesof-freedom (DoF) half-truck model considering motions in the vertical, lateral, pitch, and yaw directions. The study showed that magnitudes of friction forces obtained from the model were considerably lower than those from the NUCARS simulations.…”
In this study, the nonlinear damping characteristics of friction wedges in the secondary suspension of a freight wagon are investigated considering nonsmooth unilateral contact, multiaxis motions, slip-stick conditions, and geometry of the wedges. The parameters of the contact pairs within the suspension were identified to achieve smooth and efficient numerical solutions, while ensuring adequate accuracy. A simulation model of the friction wedge was formulated and analyzed, which revealed highly nonlinear dependence on vertical, roll, and lateral motions between the bolster and the side frames. The friction wedge model was integrated into the multibody dynamic model of a three-piece bogie to study the effects of wedge properties on hunting characteristics. The resulting 114-degrees-of-freedom wagon model incorporated constraints due to side bearings, axle boxes, and the center plates, while the wheel-rail contact forces were obtained using the FASTSIM algorithm. The simulation results were obtained to study hunting properties of the wagon in terms of critical speed and the predominant oscillation frequency, and the effects of wedge friction and geometry on stability characteristics of the freight car. The results showed subcritical Hopf bifurcation of dynamic responses of the wagon. Moreover, an increase in the wedge angle, friction coefficient, and springs free length resulted in a higher critical speed.
“…Harder 22 developed a specific element in the ADAMS platform for simulation of a specific type of wedge design, which provided a constant friction damping regardless of loading. Ballew 23 studied the effects of geometry and inertial properties of friction wedges on dynamic responses of a four-degreesof-freedom (DoF) half-truck model considering motions in the vertical, lateral, pitch, and yaw directions. The study showed that magnitudes of friction forces obtained from the model were considerably lower than those from the NUCARS simulations.…”
In this study, the nonlinear damping characteristics of friction wedges in the secondary suspension of a freight wagon are investigated considering nonsmooth unilateral contact, multiaxis motions, slip-stick conditions, and geometry of the wedges. The parameters of the contact pairs within the suspension were identified to achieve smooth and efficient numerical solutions, while ensuring adequate accuracy. A simulation model of the friction wedge was formulated and analyzed, which revealed highly nonlinear dependence on vertical, roll, and lateral motions between the bolster and the side frames. The friction wedge model was integrated into the multibody dynamic model of a three-piece bogie to study the effects of wedge properties on hunting characteristics. The resulting 114-degrees-of-freedom wagon model incorporated constraints due to side bearings, axle boxes, and the center plates, while the wheel-rail contact forces were obtained using the FASTSIM algorithm. The simulation results were obtained to study hunting properties of the wagon in terms of critical speed and the predominant oscillation frequency, and the effects of wedge friction and geometry on stability characteristics of the freight car. The results showed subcritical Hopf bifurcation of dynamic responses of the wagon. Moreover, an increase in the wedge angle, friction coefficient, and springs free length resulted in a higher critical speed.
“…The friction surfaces between a side frame and a wedge can be perpendicular to the track or have a small angle of inclination (no bigger than 3 degrees or 0.052 radians). According to the situations of the toe angle, a wedge suspension can be toe-out (Figure 3(a)), no-toe (Figure 3(b)) or toe-in (Figure 3(c)) (Steets et al., 2010a; Steets et al., 2010b; Ballew et al., 2011). Figure 3.Toe angles: (a) toe-out, (b) no-toe and (c) toe-in.…”
Wedge suspensions are critical systems for three-piece bogies. This paper proposes a methodology to optimize wedge suspensions using white-box suspension models, dynamic simulations of railway vehicle systems, parallel multi-objective Particle Swarm Optimization (pMOPSO), and parallel multi-objective Genetic Algorithm (pMOGA). Two types of original wedge suspensions with three different toe angle configurations were modeled and compared. Four case studies were carried out to prove the feasibility of the optimization methodology. A series of optimized designs were identified using the Pareto Front technique. Demonstrative optimized designs were compared with the original designs. Results show that wedge suspensions with the toe-in configuration provide better dynamic performance for freight wagons. Significant reductions to the maximum wheel/rail contact forces can be achieved by the optimized designs. Linear speed-up was achieved by using the parallel computing technique.
“…Galinė skersinė sija Priekinė skersinė sija modeliuojamų parametrų parinkimas Prekinių vagonų pakabose naudojami įvairūs tamprieji elementai. Nagrinėjant vertikaliąją dinamiką orientuojamasi ne į konkrečius tampriuosius elementus, nors tai yra svarbu, bet į vertikaliąją dinamiką veikiančias jėgų charakteristikas, t. y. į elemento vertikalios jėgos P priklausomybę nuo jo statinės deformacijos f st : P = P(f) (Ballew et al 2011).…”
Section: Vagono Kėbulasunclassified
“…Pakabos statinė deformacija, kuriai būdingos tiesinės charakteristikos, nustatoma pagal formulę (Ballew et al 2011):…”
The paper analyses the running smoothness of the rolling-stock as the main feature of wagon dynamics. The running smoothness of the freight wagon is evaluated considering the parameters of vibrations and the oscillation process. During the process of wagon running on the track, the forced oscillations of the elements of the body, chassis and suspension are excited. Four-axle freight wagon movement down the track taking into account the given vertical and lateral irregularities has been simulated using software package “Universal Mechanism”. The dependencies of the oscillation amplitudes of the wagon body on track irregularities and vertical and lateral suspension settings have been defined. The dependencies of wagon suspension settings and derailment stability on changes in the wagon mass have been examined in the paper. Finally, basic conclusions have been given.
Straipsnyje nagrinėjama viena pagrindinių vagono dinamikos savybių – važiavimo tolygumas. Riedmenų važiavimo tolygumas vertinamas jų masių svyravimo proceso ir kėbulo vibracijų parametrais. Vagonui važiuojant bėgių kelio nelygumais, sužadinami priverstiniai kėbulo, pakabos ir važiuoklės elementų svyravimai. Programiniu paketu „Universal Mechanism“ sumodeliuotas prekinio keturašio vagono važiavimas keliu, kuriame yra bėgių vertikalių ir skersinių nelygumų. Nustatyta vagono kėbulo svyravimų amplitudžių priklausomybė nuo bėgių kelio nelygumų bei vertikaliųjų ir skersinių pakabos parametrų. Straipsnyje nagrinėjama vagono pakabos parametrų ir stabilumo nuriedėjimui nuo bėgių atveju priklausomybė, kintant vagono masei. Pabaigoje pateiktos išvados.
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