“…is means that when the gearbox is mounted in the middle symmetrical position, the generation of the polygonal wear of the power wheel can effectively suppress. It is worth noting that, comparing the results of existing research [20], we get different results. Due to the differences in the materials and structure of the wheelsets between high-speed train and metro train, there are also great differences in their unstable vibration performance.…”
Section: Analysis Of Saturated Creep Force Between Wheel and Railmentioning
confidence: 83%
“…It needs to be mentioned that it is generally accepted in the brake squeal research community that the smaller the effective damping ratio is, the more likely the corresponding unstable vibration occurs. However, some researches also showed that not only the squeal corresponding to the smallest absolute value of the effective damping ratio can occur, but sometimes the squeal corresponding to a larger negative effective damping ratio can also occur [19,20]. e steps of the complex eigenvalue analysis method in finite element software ABAQUS are given below:…”
The wheels of power and trailer wheelset show different polygonal characteristics since their structures are obviously different. Therefore, the frictional self-excited vibration models of wheelset-track systems are established based on the viewpoint of the frictional self-excited vibration in reducing the wheel polygonal wear. Then, the motion stability of wheelset-track systems is studied by using the complex eigenvalue method. The results show that when the creep force between the wheel and rail is saturated, the unstable vibration frequency of the power wheelset is prone to induce 19-20th-order polygonal wear of the wheel, and the trailer wheelset is prone to induce 20-21th-order polygonal wear of the wheel. Meanwhile, the wheel polygonal wear can be effectively alleviated through changing the gearbox position of the power wheelset. And avoiding disc braking at high speeds can suppress the occurrence of wheel polygonal wear. In addition, the development tendency of wheel polygonal wear can be reduced by increasing the Young’s modulus of the brake pad, but Poisson’s ratio has little effect on the development tendency.
“…is means that when the gearbox is mounted in the middle symmetrical position, the generation of the polygonal wear of the power wheel can effectively suppress. It is worth noting that, comparing the results of existing research [20], we get different results. Due to the differences in the materials and structure of the wheelsets between high-speed train and metro train, there are also great differences in their unstable vibration performance.…”
Section: Analysis Of Saturated Creep Force Between Wheel and Railmentioning
confidence: 83%
“…It needs to be mentioned that it is generally accepted in the brake squeal research community that the smaller the effective damping ratio is, the more likely the corresponding unstable vibration occurs. However, some researches also showed that not only the squeal corresponding to the smallest absolute value of the effective damping ratio can occur, but sometimes the squeal corresponding to a larger negative effective damping ratio can also occur [19,20]. e steps of the complex eigenvalue analysis method in finite element software ABAQUS are given below:…”
The wheels of power and trailer wheelset show different polygonal characteristics since their structures are obviously different. Therefore, the frictional self-excited vibration models of wheelset-track systems are established based on the viewpoint of the frictional self-excited vibration in reducing the wheel polygonal wear. Then, the motion stability of wheelset-track systems is studied by using the complex eigenvalue method. The results show that when the creep force between the wheel and rail is saturated, the unstable vibration frequency of the power wheelset is prone to induce 19-20th-order polygonal wear of the wheel, and the trailer wheelset is prone to induce 20-21th-order polygonal wear of the wheel. Meanwhile, the wheel polygonal wear can be effectively alleviated through changing the gearbox position of the power wheelset. And avoiding disc braking at high speeds can suppress the occurrence of wheel polygonal wear. In addition, the development tendency of wheel polygonal wear can be reduced by increasing the Young’s modulus of the brake pad, but Poisson’s ratio has little effect on the development tendency.
“…It is common to model the vibratory system using the finite element approach by discretizing the continuum into several discrete finite elements. This discretized model and subsequent numerical approach to find the set of complex eigenvalues with their real and imaginary parts help identify the rate of growth and unstable frequencies of the system. , In the current study, CEA is performed to predict the possible unstable eigenfrequencies of the brake pad–disc assembly between 0 and 16 kHz for the forward cycle (speed, 20 kmph; pressure, 10 bar condition) for the brake squeal prophecy of the developed pads.…”
Aramid pulp/fiber
is the most vital ingredient of brake friction
material (FM) formulation. It is perpetually added to achieve quality
brake pads/shoes and improve the overall friction and wear performance.
Additionally, novel Zylon fibers have a superior property to aramid
fibers. However, no studies give insights on their influence on brake
noise and vibration (NV) performance. In the current work, a series
of six different types of eco-friendly brake pads was developed. The
first five contain aramid pulp, aramid short fibers, and Zylon fibers
of different sizes (1, 3, and 6 mm) as the theme ingredients (3 wt
%) by keeping the parent composition identical. Additionally, one
more pad was developed that contains no aramid/Zylon fibers (i.e.,
reference pad). The pads were characterized for physical and mechanical
properties. The damping and natural frequencies of pads were measured
experimentally and numerically. All brake pads were evaluated for
detailed NV performance by following the SAE J 2521 test schedule.
In addition, numerical simulation was performed to validate the experimental
brake squeal results. Results revealed that aramid/Zylon fiber-based
pads improved the porosity, damping, and compressibility. Overall,
brake noise and vibrations were improved for aramid/Zylon fiber-based
pads by 1.2–1.5 dBA and 20–25%, respectively, compared
to the reference pad. The complex eigenvalue analysis (CEA) proved
that squeal was mainly influenced by the damping and density of the
pad materials. Thus, aramid/Zylon fiber-based pads can effectively
suppress the instability of the brake system and reduce the brake
squeal propensity.
“…In addition, as shown in Figure 1(c), there is a frequency peak of about 1188 Hz within the frequency range of 0-1200 Hz. This frequency is the twice-order harmonic response 26 of the excitation frequency of the 24th-order wheel polygonal wear.…”
Section: Finite Element Modelling Of the Polygon-shaped Wheelmentioning
confidence: 99%
“…In addition, as shown in Figure 1(c), there is a frequency peak of about 1188 Hz within the frequency range of 0–1200 Hz. This frequency is the twice-order harmonic response 26 of the excitation frequency of the 24th-order wheel polygonal wear.Figure 1.Field measurement: (a) the typical polygon-shaped wheel tread of high-speed trains, 18 (b) the vertical vibration acceleration of the axle box of the measured trailer vehicle and (c) PSD analysis of the vertical vibration acceleration of the axle box.…”
This paper studies the effect of wheel polygonalization and material properties on the fatigue failure of fastener clips in high-speed railway lines and puts forward the corresponding inhibition measures. Vibration frequencies excited by 24th-order wheel out-of-roundness (OOR) were analysed by on-site tests of the axle box vertical vibration acceleration. A finite element modelling method of polygon-shaped wheels was proposed, which was verified by comparing the field measurement with the dynamic simulation. The dynamic response of the fastener clip was simulated by using a rigid–flexible coupled model of the wheelset-track system. The effect of amplitudes as well as typical wavelengths of wheel OOR on the fracture of the clip was analysed based on the Miner fatigue damage accumulation ruler. The results show that when the wheelset ran at 237 km/h on the track, the 24th-order wheel OOR had no obvious effect on the Mises equivalent stress of the clip. When the amplitude of the 24th-order wheel OOR reached 0.225 mm and above, excited vibrations of about 1172 Hz were transmitted from the wheelset-rail system to the fastener systems, thus reducing the safe operating life of the clips. This phenomenon can be inhibited by setting a reasonable amplitude threshold for wheel re-profiling. Wheel eccentric wear (first-order OOR) and 12th-order OOR had lesser effects on the fatigue failure of the clip. The decrease of Poisson’s ratio or the increase of Young’s modulus of the material could cause the maximum Mises equivalent stress at the clip to increase, which might induce cracks, thus leading to the fracture of the clip. Therefore, during the production process, the Poisson’s ratio and Young’s modulus of fastener clips should be strictly controlled to ensure that they are within the permitted range.
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