Study on the Response of Elastic Wheel to Excitation

The standard wheel and damped wheel model were established in ANSYS, through modal analysis to study the vibration characteristics of them. The results show that vibration of standard wheel is mainly manifested as torsion pendulum vibration of tread, radial and axial vibration of web and combination vibration of tread and web in frequency of 0～5000Hz.In this frequency range, 0~1000Hz mainly manifested as torsion pendulum vibration of the tread, above 1000Hz, these three have the performance, especially in the web vibration is most active, therefore, Web is the primary noise radiation source in the standard wheel structure. The mode shape of damped wheel is same as standard wheel in the range of 0~5000Hz, mainly manifested as torsion pendulum vibration of tread, radial and axial vibration of web and combination vibration of tread and web.

The acoustic black hole structure is used for high-frequency vibration and noise reduction of the structure. It uses the gradient change of the geometric parameters of the thin-walled structure or the material characteristic parameters to gradually reduce the propagation speed of the wave in the structure and cannot reach the boundary. Realize vibration reduction and noise reduction of elastic waves and energy recovery. As an effective method to deal with many vibration and noise reduction problems, acoustic black holes are currently being studied by many scholars as a hot topic. Most of the studies are based on the thickness variation law as a power function. However, more in-depth research has not been carried out on the acoustic black hole structure whose thickness variation law is other functions. In this paper, the finite element simulation method is mainly used to study the vibration reduction effect of the acoustic black hole structure with four function laws: the traditional quadratic power function, the trigonometric function, the exponential function and the logarithmic function, and compare the four function laws. Vibration reduction effect of one-dimensional acoustic black hole beam structure. The research and calculation results show that in the one-dimensional acoustic black hole beam structure with four function laws, the logarithmic function has a better vibration reduction effect in the low frequency range, while the power function is the best choice in the middle and high frequency range. It provides a certain reference value for the design and selection of acoustic black hole structures in different frequency bands in the future.

Torque vectoring algorithm based on mechanical elastic electric wheels with consideration of the stability and economy

Characteristics of atmosphere‐generated seismic noise below 0.05 Hz are investigated when surface pressure is large. In this paper, large pressure means pressure power spectral density exceeding 100 Pa2/Hz (at 0.01 Hz). We discuss three main points. The first point is existence of two frequency ranges that show high coherence between co‐located pressure and vertical seismic data. The lower frequency (LF) range is broad and its upper bound is about 0.002 Hz. The higher frequency (HF) range is bounded between about 0.01 and 0.05 Hz. Phase difference between pressure and vertical displacement is different for the two ranges. The LF range shows phase difference of zero, and the HF range shows phase difference of 180°. The second point is on the excitation mechanism in the HF range. Using theory and data, we show that seismic noise in the HF range is primarily excited by wind‐related pressure. When pressure is high, wind speeds become high, and wind directions become unidirectional. In such a case, a deterministic, moving pressure‐source by Sorrells (1971, https://doi.org/10.1111/j.1365-246X.1971.tb03383.x) captures the characteristics of data better than stochastic source models. The third point is on the cause of phase differences between the LF range and the HF range. The root cause is that, even after removing the instrument response, vertical seismic data contain effects from gravity and Earth rotation. Gravity effects become significant for frequencies below 0.005 Hz and create discrepancies between deconvolved vertical displacements and true vertical ground displacements. Phase‐difference results are naturally explained by it.

A computational study of helicopter vibration and rotor shaft power reduction is conducted using activelycontrolled trailing-edge flaps (ACFs), implemented in both single and dual flap configurations. Simultaneous vibration reduction and performance enhancement is demonstrated under level flight condition at high advance ratios, where dynamic stall effects are significant. Power reduction is achieved using the adaptive Higher Harmonic Control (HHC) algorithm in closed loop, with 2-5/rev flap control harmonics. This approach is compared with an off-line, nonlinear optimizer available in MATLAB, and favorable comparisons are obtained. A parametric study of flap spanwise location is also conducted to determine its optimal location for power reduction. The effectiveness of the ACF approach for power as well as simultaneous vibration and power reduction is also compared with conventional individual blade control (IBC) approach. Rotor power reduction and simultaneous reduction of vibration and power are shown to be larger at higher rotor thrust and advance ratio. Finally, the effect of active flap on dynamic stall is examined to determine the mechanisms of rotor power reduction. The simulation results clearly demonstrate the potential of the ACF system for power reduction as well as simultaneous vibration and power reduction. Nomenclature c Blade chord cc Flap chord CT Rotor thrust coefficient D Matrix defined as TTQT+R fb(.) Blade equations of motion ft(.) Trim equations FHX4,FHY4, FHZ4 4/rev hub shears, nondimensionalized by MbΩR MHX4,MHY4, MHZ4 4/rev hub moments, nondimensionalized by MbΩR J Quadratic-form objective function to be minimized Presented at the American Helicopter Society 62nd Annual Forum, Phoenix, AZ, June 9-11, 2006. 1 Mb Blade mass mc Flap mass per unit length, nondimensionalized by Mb/R MHz1 Yawing moment about rotor hub Nb Number of rotor blades PR Rotor shaft power, nondimensionalized by MbΩR qt Vector of trim variables qti Vector of trim variables at i-th control step Q Weighting matrix for objectives to be minimized R Weighting matrix on control input R Rotor blade radius Rt Trim residuals vector T Sensitivity, transfer matrix between control inputs and objective function uk Control input vector, kth control step uk,opt Optimum value of control input vector xc Spanwise location of center of control surface zk Objective vector, kth control step αR Rotor shaft angle of attack δ f Flap deflection angle ∆Cd,flap Additional drag due to flap deflection δNc,δNs N/rev cosine and sine amplitude of δ βp Blade precone angle γ Lock number μ Helicopter advance ratio ωF , ωL, ωT Blade flap, lead-lag and torsional natural frequencies Ω Rotor angular speed ψ Rotor azimuth angle φR Lateral roll angle θ0,θ1c,θ1s Collective and cyclic pitch components θ0t Tail rotor collective pitch θtw Built-in twist angle σ Rotor solidity Introduction and Background Specifications for noise and vibration levels in rotorcraft are continuously increasing in stringency, thus motivating research related to active noise and vibration reduction. Desirable vibration levels have been identified to be below 0.05g to provide passengers with “jet smooth” ride (Ref. 1). A number of active control techniques have emerged for effective vibration reduction (Refs. 1,2), as illustrated schematically in Fig. 1. These approaches generally fall into one of two categories: (a) active control approaches aimed at reducing vibrations in the rotor before they propagate into the fuselage, and (b) active control approaches

The vibration and noise are the main hazards of rail transit. In order to achieve the purpose of reducing vibration and noise, we employ the constrained damping method on the wheel and rail; use finite element software to set a finite element model of standard wheel rail and damped wheel rail; then give them harmonic response analysis. The results showed that: the main resonance frequency of the standard wheels is at 2000 ∼ 4000 Hz; the main resonance frequency of the standard rail of is at 800 ∼ 4500 Hz; the reducing vibration effects of the damped wheel-rail are mainly at the centralized area of the resonant frequency response. Compared with the standard wheel and rail, the vibration response peak value of damped wheel-rail has significantly weakened. Under the wheel-rail loading, maximum axial and radial vibration response value of damped wheel-rail is around 30-35% of the standard wheel-rail, with vibration reduction rate up to 65-70%.

The purpose of this study was to measure the vibration levels in commercial truck shipments in Thailand and observe the effects on packaged fruit. The study measured the vibration levels in two of the most commonly used truck types to ship packaged goods as a function of road condition and vehicle speed. The suspension type on the trailers studied was leaf-spring. The results of damage to packaged tangerine fruit as a function of location in the payload are also presented. The data presented in this study will assist product and package designers to reduce damage in transit. The results showed that vibration levels increased with speed and as a result of road condition. Analysis of variance indicated that three controlling factors, road surface, truck speed and truck type, significantly affected (p ≤ 0.05) peak PSD, PSD* (root mean square) over the frequency range 2–5 Hz, and fruit damage. As expected, based on previous work, an increase in truck speed resulted in an increase in vibration levels and damage to packaged fruit. The laterite road condition produced the highest vibration level for a given truck and travelling speed followed by concrete highway and asphalt road conditions. Fruit damage was found to be greatest in the uppermost container for every combination of road, truck type and travelling speed, which also corresponded to the highest vibration levels recorded. The results showed that a significant amount of damage can occur on unpaved roads (laterite), while the packages are transported from farms and harvesting areas to regional truck terminals. Damage on asphalt road conditions was minimal. This paper provides an updated history of measured and quantified levels of vibration for these specific trucks and road conditions. Copyright © 2005 John Wiley & Sons, Ltd.

In-wheel suspension systems for manual wheelchairs offer a potential remedy for dissipating whole body vibrations; however, some users feel that they impede their propulsion efficiency. The purpose of this study was to compare Loopwheel Urban, a type of in-wheel suspension wheel to a carbon fiber wheel (Spinergy CLX) and standard spoked wheel to elucidate their comparative effects on rolling resistance force and axle deformation. Component-level drum-based testing revealed that the average rolling resistance force of the Loopwheels was 118% and 44% higher on linoleum and carpet surfaces than the standard wheels, respectively, and approximately 160% higher on carpet than the Spinergy CLX. Loopwheels demonstrated greater deformation (70 mm average across all loading conditions) compared to both standard and CLX wheels under static loading conditions. The increased rolling resistance force and deformation may help explain the perception among manual wheelchair users that Loopwheels impede their propulsion efficiency, despite their smoother ride and reduction of vibrations and shocks.

The growing popularity of electric vehicles EV is mostly related with state measures aimed at selling new automobiles with reduced emissions of dangerous substances into the atmosphere. Emission standards enshrine this. The usage of in-wheel electric motors is one solution to the exhaust pollution problem. this paper evaluates the impact of an in-wheel motor IWM suspension system on the ride comfort and road holding of an electric vehicle EV. To investigate the impact of the IWM suspension system on vehicle ride comfort, a dynamic vehicle quarter model with 1-DOF is created using a combination of road surface profile excitations and in-wheel motor. To achieve the target of this paper, a complete control system is implemented; this control system is prepared using MATLAB and consists of three components: the input signals (the actuator force and the road surface profile), a fuzzy PID controller, and the suspension model. The simulation results illustrate a comparison of the suspension system's performance in two scenarios: when the standard wheel is used and when IWM is used. This study showed that the IWM used gave a negative result on the performance of the system because of its extra weight, even if this effect was small compared to the suspension system performance when using standard wheels.

The elastic vibration of a railway carbody influences a riding quality, and vibration reduction is required. The first mode of the elastic vibration of the carbody can be reduced by using dynamic vibration absorber (DVA) effect utilizing bogie-carbody dynamic interaction proposed in the previous paper. On the other hand, vibration increases in high frequency range. In this paper, the damper having frequency dependent characteristic is proposed to reduce the elastic vibration of the carbody in high frequency range. It has high damping in low frequency range to get DVA effect, and low damping in high frequency range to obtain the isolation effect for input from the truck. A prototype damper having plastic valve as like an orifice is manufactured. The sectional area of the orifice is varied by velocity of the piston, and damping characteristic can be switched in high frequency range. In order to estimate the damping coefficient, vibration test is carried out. Finally, dynamic characteristic of the damper is investigated experimentally.

This paper develops an integrated model of periodic 1-D structures with piezoelectric actuators for complete active/passive control. The approach utilizes the property of periodic structural components that create a stop band region in the frequency spectra, predominantly in the higher frequency range. This basic property of periodic structures is enhanced by the application of periodically placed piezoelectric actuators, with piezo forces as a function of displacement. With this control capability, the piezoelectric actuators can introduce the proper force to reduce wave propagation, both in higher and lower frequency range. An analytical model is developed to predict the performance of the periodic rods and beams with piezoelectric actuators acting as controllers. For the purpose of this research, only geometric variations are considered and every cell is assumed to be identical.

The Very High Frequency (VHF) range extends from 30MHz to 300 MHz, which means that when a VHF sine‐wave signal is observed on an oscilloscope, the trace completes from 30 to 300 million cycles each second. The wavelength and frequency of VHF signals has a profound impact on the hardware we build to use these frequencies. The 30 to 300MHz frequency range has been popular since radio engineers first discovered how to reliably generate and amplify VHF signals during the 1930s. The VHF range has significant advantages for some common applications over higher and lower frequency ranges.

The Very High Frequency (VHF) range extends from 30MHz to 300 MHz, which means that when a VHF sine‐wave signal is observed on an oscilloscope, the trace completes from 30 to 300 million cycles each second. The wavelength and frequency of VHF signals has a profound impact on the hardware we build to use these frequencies. The 30 to 300MHz frequency range has been popular since radio engineers first discovered how to reliably generate and amplify VHF signals during the 1930s. The VHF range has significant advantages for some common applications over higher and lower frequency ranges.

As is known, reactions that result in the oxidation of carbon and form a large volume of carbon monoxide take place in the reaction zone of converters when the bath is blown with oxygen. The pulsating nature of gas evolution in this case generates a spherical longitudinal wave that propagates in the bath and the lining and results in vibration of the converter. Theoretical and experimental studies show that the level of vibration is determined by the dynamics of oscillatory" phenomena occurring during evolution of the gas. The level of vibration is related to the kinetics of decarbonization taking place in the secondary reaction zones of the furnace [1]. Thus, vibration level may serve as an indirect indicator of the rate of oxidation of carbon in the converter bath. This idea was the foundation for a system developed by the State Metallurgical Academy of the Ukraine for vibration monitoring of deearbonization and prediction of carbon content at the end of the blow. The system has successfully completed commercial trials in 60-ton converters at the Dnepropetrovsk plant. Figure t presents a dia~am showing the location of the main elements of the system. A vibration pickup, preamplifier, and function converter are mounted on the undriven trunnion of the converter. An electric signal proportional to the rate of decarbonization is sent along a cable from the function converter to the control panel of the furnace. The following is located on the control panel: main (logic) block: recording unit, to record the curve of the resulting vibration signal; illuminated signal panel, to predict carbon content at the end of the blow. Figure 2 shows the character of change in the level of vibration in a typical heat. As on other converters [2], on the whole the change in vibration level reflects generally accepted representations on the dynamics of decarbonization in the converter bath. Vibration level is lowest in period I, when iron, silicon, and manganese oxidation reactions take place and almost no carbon is oxidized. An increase in temperature is accompanied by "ignition" of the melt, and both vibration level and carbon oxidation rate increase (period [I). The vibration level in period III indicates that the development of the decarbonization process has reached a maximum. The level of vibration and the rate of carbon oxidation decrease at carbon contents below 0.25-0,35 % (period W). A characteristic feature of steelmaking in the 60-ton converters at the plant is the raising and lowering of the lance in the second half of the blow. In this case, the strength of the vibration signal changes in accordance with known laws governing the effect of lance position on decarbonization processes. Raising the lance reduces the degree of assknilation of oxygen during the oxidation of carbon and decreases decarbonization rate and signal strength. Lowering the lance increases the assimilation of oxygen by the converter bath and intensifies the oxidation of carbon, which is accompanied by an increase in the strength of the vibration signal. The easily detected reduction in the strength of the vibration signal at the end of the blow was used to predict the carbon content of the bath and stop the blow at the proper time toward the end of the heat. The reduction in decarbonization rate and the corresponding reduction in signal strength at the end of the blow occurred at a certain carbon content in the bath. For example, a 14-20% reduction in vibration level relative to the maximum value corresponded to a concentration of 0200.25% C in the bath. A carbon concentration on the order of 0.1,1-0.18% was predicted when vibration level decreased 2030%. A reduction in vibrations by more than 40% corresponded to a carbon concentration below 0.1% in the bath.

In order to make up for the disadvantages of common wheels, a novel type of mechanical elastic electric wheel (MEEW) structure is designed and applied to electric vehicles in this paper. To improve ride comfort and stabilize the attitude of the motor system, an improved adaptive backstepping control strategy with nonlinear disturbance observer (NDOB) technology is further constructed for electric vehicle equipped with MEEW system. In consideration of uncertain factors and nonlinear characteristics, the quarter vehicle model of active suspension and MEEW system is established. An adaptive control strategy is adopted based on backstepping technique, which can simultaneously estimate uncertain sprung mass and unknown stiffness or damping coefficients. Meanwhile, the designed disturbance observer is able to suppress the influence of external lumped disturbance and compensate estimation errors. Finally, simulation experiments are developed to demonstrate the advantages of proposed control scheme and verify the effectiveness of designed observer in the presence of uncertain disturbance.