Torsional Resonance Research Articles

Robust algorithm of indirect tyre pressure monitoring system based on tyre torsional resonance frequency analysis

• Detects changes in tyre pressure by monitoring changes in tyre resonance frequency. • Eliminating the disturbances of engine and driveline on frequency estimation. • Key parameters for evaluating tyre torsional vibration characteristics is proposed. • Methods proposed to compensate for the effects of road roughness and ambient temperature. • The proposed algorithm improves the robustness of frequency estimation. This paper focuses on an indirect Tyre Pressure Monitoring System (TPMS) algorithm based on frequency analysis of tyre torsional vibration. Tyre vibration is analysed using a tyre structure model, and the tyre resonance frequency is estimated using an Autoregressive (AR) model. The vibration disturbances from the engine and driveline that affect the estimation of the tyre torsional frequency are analysed, and a notch filter is designed to eliminate the disturbances. The torsional vibration of the driveline is identified by the correlation analysis of driving wheel speed. Two qualitative evaluation indexes of tyre torsional vibration characteristics are proposed. The corresponding quantitative parameters are used to determine the tyre torsional vibration state to eliminate the interference of undesirable vibration states on the frequency calculation. A road roughness estimation method is proposed based on tyre vertical vibration information in the wheel speed. The estimated road roughness parameters compensate for the calculated resonance frequency affected by road roughness. Based on the relationship between measured resonance frequency and temperature under a constant tyre pressure condition, the frequency variation value affected by tyre rubber stiffness variation due to temperature variation is calculated using the ambient temperature signal. The calculated resonance frequency is corrected to eliminate the coupling effect of gas stiffness and rubber stiffness, the impact of temperature variation on tyre pressure estimation is compensated. The results of vehicle road tests demonstrate the robustness of the proposed tyre pressure monitoring algorithm.

Physical realization and experimental validation of effective phononic crystals for control of radial torsional waves

Recently, the concept of effective phononic crystals (EPCs) and locally resonant effective phononic crystals (LREPCs) have been proposed to enable properties of phononic crystals (PCs) and acoustic metamaterials (AMs), respectively, in radially propagating waves. This problem is not straightforward since the equations of motion of radially periodic systems do not have periodic coefficients and thus Bloch solutions in these radially periodic systems are not valid. To overcome this, EPCs and LREPCs use radially dependent properties to force periodic coefficients in the equations of motion of radial elastic waves, enabling the application of the Bloch theorem and thus allowing for properties of PCs and AMs. However, the required radially dependent properties severely complicate their physical realization, since modulus and density must be tailored such that they follow a specific radial variation. In this paper, we propose a method to physically realize an LREPC by radially varying its impedance through spatial changes to its out-of-plane thickness. Physical realization of the LREPC also involves local torsional resonances. In contrast to typical AMs, the resonators in the LREPC must be geometrically different to retain the same torsional stiffness and moment of inertia at different radii. We use additive manufacturing plus traditional machining to fabricate the LREPC. We introduce an experimental setup to measure radially propagating torsional waves in the LRPEC and show how to decouple torsional vibrations from bending vibrations to accurately measure transmission. To show the importance of using an LREPC, we compare its dynamic response to a locally resonant homogenous system (LRHS), a system that is radially periodic but has non-periodic equations of motion. Measured transmission shows that only the LREPC attenuates waves inside the band gap frequencies predicted by Bloch analysis. This work experimentally shows that LREPCs allow for the application of well-known concepts of AMs to control radially propagating torsional waves.

Self-Sensing WS2 Nanotube Torsional Resonators.

We demonstrate self-sensing tungsten disulfide nanotube (WS2 NT) torsional resonators. These resonators exhibit all-electrical self-sensing operation with electrostatic excitation and piezoresistive motion detection. We show that the torsional motion of the WS2 NT resonators results in a change of the nanotube electrical resistance, with the most significant change around their mechanical resonance, where the amplitude of torsional vibrations is maximal. Atomic force microscopy analysis revealed the torsional and bending stiffness of the WS2 NTs, which we used for modeling the behavior of the WS2 NT devices. In addition, the solution of the electrostatic boundary value problem shows how the spatial potential and electrostatic field lines around the device impact its capacitance. The results uncover the coupling between the electrical and mechanical behaviors of WS2 and emphasize their potential to operate as key components in functional devices, such as nanosensors and radio frequency devices.

On the band gap formation in locally-resonant metamaterial thin-walled beams

This paper is concerned with flexural and torsional waves propagation in locally-resonant thin-walled beams with open cross section. A beam with monosymmetric cross section hosting a periodic array of translational and torsional resonators is considered. The resonators are designed to protect the beam from both vertical and lateral dynamic loads; while vertical loads acting in the symmetry plane induce flexural waves only, vertical loads acting out of the symmetry plane and lateral loads induce coupled flexural–torsional waves due to the monosymmetry of the beam cross section. Aim of the paper is to investigate the dispersive properties of the locally-resonant beam under consideration, focusing on coupled flexural–torsional waves. For this purpose, a homogenization approach is adopted to derive a simplified dispersion equation of the infinite locally-resonant beam. Starting from the observation that the latter equation is equivalent to the dispersion equation of a uniform infinite beam with homogenized inertial properties, it is possible to identify the location and the amplitude of band gaps; remarkably, it is found that band gaps for coupled flexural–torsional waves are located in the frequency region where the matrix of the homogenized inertial properties is negative definite. Further, it is demonstrated that band gaps arise when translational and torsional resonators are simultaneously connected to the beam and are tuned to the same frequency; on the other hand, band gaps are not guaranteed if only translational resonators or only rotational resonators are connected to the beam. Alternative exact methods based on the transfer matrix approach and the theory of generalized functions are employed to validate and substantiate the obtained results.

The torsional nonlinear-elastic parameter βG for uniaxial stress monitoring of concrete specimens

Nonlinear elastic characterization of concrete materials is a promising approach for actual stress detection in structural elements. In this study we investigate the use of the “torsional nonlinear parameter” βG of elongated concrete specimens to detect the actual uniaxial stress level. We derive a theoretical expression of βG ex-pressed in terms of the third order elastic constants l, m and n. Then we apply quasistatic uniaxial loading cycles on a 15 x 15 x 60 cm3 specimen and measure βG using the torsional resonance technique, obtaining an average βG = -125. This re-sult is compared against the βG measured using ultrasonic wave propagation in the same specimen during the same test. Finally, we measure βG in a real size reinforced concrete column using the torsional resonance technique, obtaining βG =-650. A final discussion is posed to analyze the findings and to guide future research.

Formation mechanism of short-pitch rail corrugation on metro tangent tracks with resilient fasteners

A type of short-pitch rail corrugation on tracks with resilient fasteners called ‘Vanguard’ fasteners is widely found on different metro lines in China. Field measurements and numerical calculations are used to investigate the cause of the corrugation formation. The corrugation with wavelengths of 30–60 mm occurs on both the curved and straight tracks through field measurements. Corrugation passing frequencies are in the range of 340–700 Hz. The frequencies of pinned-pinned resonance, the P2 resonance and the wheelset torsional resonance are far away from the corrugation passing frequencies. The investigated results show the vertical dynamic characteristic of the track is the main factor for occurrence of the short-pitch rail corrugation. The short-pitch rail corrugation arises by a wavelength-fixing mechanism of rail vertical bouncing on the resilient fasteners. The corrugation wavelength mainly is related to the vertical stiffness of the rail fasteners. Rail corrugation with wavelengths of 25–63 mm easily occurs on tracks with resilient fasteners with the vertical stiffness of less than 20 MN/m.

Micropillared Surface to Enhance the Sensitivity of a Love-Wave Sensor

Surface-acoustic-wave (SAW) sensors have undergone outstanding developments during the last decades. However, for biosensing applications, they struggle to compete with optical sensing technologies. In this work, we present a Love-wave-based sensing platform that leverages the use of the local resonances of micropillars fabricated on the surface of the guiding layer. We demonstrate numerically and experimentally that the Love-wave interaction with the micropillars produces sharp attenuation dips in the transmission spectrum. These dips are associated with the excitations of flexural and torsional resonance modes of the pillars. We utilize these modes to achieve higher detection sensitivity of temperature variation and mass loading using sugar and microbeads concentrations in aqueous solutions. Integrating a lattice of micropillars into SAW-based devices offers a strong potential for detecting low particles concentrations.

Master-slave synchronous control method for attenuating dual mode electromechanical transmission system torsional vibration

The high-power electromechanical transmission (EMT) system is a typical dual-mode hybrid power transmission system. The torque fluctuation of internal combustion engine causes serious shock and vibration problems of EMT. Suppressing torsional vibration based on high dynamic motor torque regulation is an important way to improve the working life and stability of EMT system. First, a lbased on the lumped parameter linear dynamic model,the torsional vibration characteristics are analyzed. Second, a fluctuating speed estimation method is proposed based on the uniformly accelerated motion model and linear regression, and a digital high pass filter is designed. Then, a master-slave coupling active torsional vibration control strategy is proposed, and a PD control algorithm based on speed feedback is designed. The variation rules of control parameters is analyzed. Finally, the control effect is verified by experiments. The results show that the lever coefficient K ab and differential coefficient K d of master-slave control can change the natural frequency of torsional vibration of the system, thus significantly changing the vibration response of the system. Selecting appropriate control parameters can achieve peak clipping of EMT torsional resonance.

Extraction algorithm for longitudinal and transverse mechanical information of AFM

The atomic force microscope (AFM) can measure nanoscale morphology and mechanical properties and has a wide range of applications. The traditional method for measuring the mechanical properties of a sample does so for the longitudinal and transverse properties separately, ignoring the coupling between them. In this paper, a data processing and multidimensional mechanical information extraction algorithm for the composite mode of peak force tapping and torsional resonance is proposed. On the basis of a tip–sample interaction model for the AFM, longitudinal peak force data are used to decouple amplitude and phase data of transverse torsional resonance, accurately identify the tip–sample longitudinal contact force in each peak force cycle, and synchronously obtain the corresponding characteristic images of the transverse amplitude and phase. Experimental results show that the measured longitudinal mechanical characteristics are consistent with the transverse amplitude and phase characteristics, which verifies the effectiveness of the method. Thus, a new method is provided for the measurement of multidimensional mechanical characteristics using the AFM.

A high-dimensional model to study the self-excited oscillations of rotary drilling systems

This paper analyzes the self-excited axial and torsional vibrations of rotary drilling systems with a model that combines a multi-degrees of freedom representation of the drilling structure with a rate-independent bit-rock interface law. The state-dependent delay introduced by the bit-rock interaction is captured by a bit trajectory function, which leads to the formulation of a nonlinear system of coupled partial differential equation (PDE) and ordinary differential equations (ODEs). This paper describes an algorithm that utilizes the Chebyshev spectral method to convert the system of PDE–ODEs into a system of coupled ODEs. The use of Chebyshev polynomials rather than Fourier series leads to a computationally more efficient algorithm, in view of the non-periodic nature of the bit trajectory function. By linearizing the system of coupled PDE–ODEs, this algorithm is further extended to assess numerically the stability of the high-dimensional model. The predictions of the linear stability analysis are validated with published results as well as with time-domain simulations. It is shown, as anticipated by Liu et al. (2014), that the stable region in the space of the operating parameters shrinks with increasing spatial resolution of the high-dimensional model, suggesting that the effects of damping on the stability of drilling system is generally negligible in the range of practical drilling parameters. Extensive parametric studies have been carried out using the high-dimensional model to analyze the influence of various factors on the torsional stick–slip oscillations. The bit wearflats are shown to play an important role in delaying or even suppressing the occurrence of torsional stick–slip oscillations. Finally, the axial vibrations propagating along the drillstring are revealed in the form of traveling waves, whereas the torsional vibrations take the form of standing waves, whose frequency is the same as the torsional resonance of the drillstring excited by the bit-rock interaction.

Review on Performance of Dual Mass Flywheel over Conventional Flywheel

The Dual Mass Flywheel is used for dampening the oscillations created at the time of working in automotive power transmission system.Dual mass flywheel is a multi-clutch device. The torsional frequency is defined as the rate at which the torsional vibration produced. When the torsional frequency of the crankshaft is equal to the transaxles torsional frequency an effect known as the torsional resonance occurs. When the operating speed of the engine is minimum, vibration occurs due to the torsional resonance and this can be avoided using dual mass flywheel.We explained detailed initial model in the paper. In this mainly having the two arc springs and two masses in the DMF and their nature. By experiment the Dual Mass Flywheel model is compared to convention flywheel. Finally the observation of the engine torque using the DMF is taken. The DMF is manufactured and done experiment or testing to see the results. And then results which came are compare with the conventional flywheel.

Ionic liquids on uncharged and charged surfaces: In situ microstructures and nanofriction

In situ changes in the nanofriction and microstructures of ionic liquids (ILs) on uncharged and charged surfaces have been investigated using colloid probe atomic force microscopy (AFM) and molecular dynamic (MD) simulations. Two representative ILs, [BMIM][BF4] (BB) and [BMIM][PF6] (BP), containing a common cation, were selected for this study. The torsional resonance frequency was captured simultaneously when the nanoscale friction force was measured at a specified normal load; and it was regarded as a measure of the contact stiffness, reflecting in situ changes in the IL microstructures. A higher nanoscale friction force was observed on uncharged mica and highly oriented pyrolytic graphite (HOPG) surfaces when the normal load increased; additionally, a higher torsional resonance frequency was detected, revealing a higher contact stiffness and a more ordered IL layer. The nanofriction of ILs increased at charged HOPG surfaces as the bias voltage varied from 0 to 8 V or from 0 to —8 V. The simultaneously recorded torsional resonance frequency in the ILs increased with the positive or negative bias voltage, implying a stiffer IL layer and possibly more ordered ILs under these conditions. MD simulation reveals that the [BMIM]+ imidazolium ring lies parallel to the uncharged surfaces preferentially, resulting in a compact and ordered IL layer. This parallel “sleeping” structure is more pronounced with the surface charging of either sign, indicating more ordered ILs, thereby substantiating the AFM-detected stiffer IL layering on the charged surfaces. Our in situ observations of the changes in nanofriction and microstructures near the uncharged and charged surfaces may facilitate the development of IL-based applications, such as lubrication and electrochemical energy storage devices, including supercapacitors and batteries.

Internal instability of thin-walled beams under harmonic moving loads

Frequent resonance may result in excessive vibrations and endanger the safety of bridges. Firstly, the governing equations of motion are derived for the vertical, lateral and torsional vibrations of a mono-symmetric thin-walled box beam under a harmonic moving load. Then the resonance conditions are derived by letting the denominator of the response of concern equal to zero. For the mono-symmetric beam, the vertical resonance is uncoupled, but the torsional and lateral resonances are coupled. When in vertical resonance, the vertical motion of the beam will diverge by growing to a maximum during the acting period of the moving load. Similar phenomenon exists for the torsional–flexural resonance. A specific case occurs when the above two resonance frequencies coincide, for which the critical length of the beam can be determined. The phenomenon of simultaneous resonance is a kind of internal instability featured by the fact that the beam can transform repetitively from the vertical mode to the torsional–flexural mode, and vice versa, with no additional energy input. To avoid the inherent internal instability, a beam should be designed with a length not equal or close to the critical length presented in this paper. All the aforementioned resonances have been extensively studied for cases involving both harmonic and random moving loads and validated by the finite element analysis.

Manipulation of the topology and solid-state spin using a mechanic-based hybrid system

In this paper, a three-body hybrid quantum system with the solid-state spin and topological qubit both mediated by a torsional nanomechanical resonator (NMR) is built by taking advantage of two different coupling mechanisms, the so-called strain and the magnetism, respectively. Two basic quantum manipulation (QM) schemes with respect to the quantum interface for arbitrary-state transfer and two-qubit Mølmer–Sørensen (MS) gate are also studied here. Then the efficiency for both QM processes is also systematically estimated, even under the influence of all kinds of adverse factors such as dissipation, decoherence and dephasing. This work may provide an extensible route towards a wider range of applications in quantum manipulation.

Nonlinear torsional primary resonance analysis of suspension bridge with generalized configuration using mathematical model

Torsional vibration of long span suspension bridge can be commonly induced by various sources, and detailed investigation is required from both design and safety point of view. This study proposes a continuum model of the generalized suspension bridge using the Hamilton principle. This model can consider any inclination angle of main cables. The horizontal and vertical motions of main cables, and torsional motion of deck are considered individually in this model. The proposed model is verified by comparing its modal properties with those from a finite element model. The nonlinear primary resonances of the two lowest torsional modes are studied through multiple-scale method (MSM) under harmonic excitation. The effects of system parameters, such as inclination angle of hangers, sag-to-span ratio, tensile stiffness of main cable and torsional stiffness of deck, on the resonance responses are investigated in this study. Results show that, increasing inclination angle of main cable and torsional stiffness of deck can intensify the softening feature of the system. In contrast, increasing the sag-to-span ratio and tensile stiffness of main cable can strengthen the hardening feature.

Periodic in-filled pipes embedded in semi-infinite space as seismic metamaterials for filtering ultra-low-frequency surface waves

The use of artificial periodic structures such as periodic wave barriers and seismic metamaterials has attracted attention as an effective approach to reduce the impact of ambient vibrations or earthquakes. In previous research, a large amount of steel was usually used in the design of seismic metamaterials to achieve ultra-low surface wave band gaps (BGs). However, the use of such large amounts of steel is inconvenient and expensive in practical engineering applications. To address this issue, this study considered the use of common building materials, namely, concrete, rubber, and soil, for the preparation of seismic metamaterials. Using these three materials, a one-dimensional (1D) seismic metamaterial composed of periodic in-filled pipes and a substrate was proposed. Ultra-low surface wave BGs (0–10 Hz) of the seismic metamaterial were identified using the sound cone method. Several important geometrical and material parameters that could influence the BGs were studied. Based on the 1D metamaterial, a 2D seismic metamaterial with a complete ultra-low BG was proposed to filter Rayleigh waves at any angle in the surface plane. The screening effectiveness of the 1D and 2D seismic metamaterials was evaluated using 2D and 3D numerical models, respectively. The results show that the ultra-low BG width decreases with an increase in the distance between two adjacent in-filled pipes. The small height of the in-filled pipe is beneficial for achieving a large ultra-low BG. A high elastic modulus and a low mass density of the soft filling material correspond to a large ultra-low BG width. The generation of ultra-low BGs in both 1D and 2D seismic metamaterials is attributed to the torsional resonance of the filling soft material. This study can serve as a reference for the design of new seismic metamaterials with practical value in engineering.

Locally Resonant Effective Phononic Crystals for Subwavelength Vibration Control of Torsional Cylindrical Waves

Abstract Locally resonant materials allow for wave propagation control in the subwavelength regime. Even though these materials do not need periodicity, they are usually designed as periodic systems since this allows for the application of the Bloch theorem and analysis of the entire system based on a single unit cell. However, geometries that are invariant to translation result in equations of motion with periodic coefficients only if we assume plane wave propagation. When wave fronts are cylindrical or spherical, a system realized through tessellation of a unit cell does not result in periodic coefficients and the Bloch theorem cannot be applied. Therefore, most studies of periodic locally resonant systems are limited to plane wave propagation. In this article, we address this limitation by introducing a locally resonant effective phononic crystal composed of a radially varying matrix with attached torsional resonators. This material is not geometrically periodic but exhibits effective periodicity, i.e., its equations of motion are invariant to radial translations, allowing the Bloch theorem to be applied to radially propagating torsional waves. We show that this material can be analyzed under the already developed framework for metamaterials. To show the importance of using an effectively periodic system, we compare its behavior to a system that is not effectively periodic but has geometric periodicity. We show considerable differences in transmission as well as in the negative effective properties of these two systems. Locally resonant effective phononic crystals open possibilities for subwavelength elastic wave control in the near field of sources.

Shafting Torsional Vibration Analysis of 1000 MW Unit under Electrical Short-Circuit Fault

Taking a 1000 MW turbine generator as the research object, the short-circuit fault in electrical disturbance is analyzed. Since it is very difficult to carry out fault analysis experiments and research on actual systems, simulation analysis is one of the more effective means of electrical fault diagnosis; the simulation’s results approach the actual behavior of the system and are ideal tools for power system analysis, and can provide an empirical basis for practical applications. The short-circuit fault model of the SIMULINK power system is built to analyze the two types of faults of generator terminals short-circuit and power grid short-circuit. The impact load spectrum, fault current and speed fluctuation between low-voltage rotors were extracted and analyzed. The conclusion is that the impact value of electromagnetic torque at the generator terminal is greater than that on the power grid side. The impact value of a two-phase short-circuit at the generator terminal is the largest, and that of a three-phase short-circuit on the power grid side is the smallest. The transient impulse current of a three-phase short-circuit at any fault point is greater than that of a two-phase short-circuit; the impulse current of the grid side short-circuit is much greater than that of the generator terminal short-circuit; the speed fluctuation and fluctuation difference caused by the three-phase short-circuit in the grid side are the largest. The alternating frequency of the transient electromagnetic force of the four kinds of faults avoids the natural frequency of the torsional vibration of the shaft system, and the torsional resonance of the shaft system in the time domain of the short-circuit fault will not appear. However, after the fault is removed, the residual small fluctuation torque in the system has a potential impact on the rotor system. This research shows an analysis of the structural integrity and safe operation of turbine generator units after a short-circuit fault, which can not only be applied to engineering practice, but also provide a theoretical basis for subsequent research.

Modeling, calculation, and analysis of torsional vibration characteristics of the hydrodynamic transmission system in engineering vehicle

According to the typical working conditions of a loader and considering the complexity of the working conditions, the hydrodynamic transmission powertrain system was modeled in this study. Because the hydrodynamic torque converter is a flexible fluid transmission component in the transmission system, this study proposes and establishes equivalent variable damping and equivalent variable stiffness models of the hydrodynamic torque converter. Based on this, a torsional vibration simulation model of the loader with variable damping and stiffness is proposed, and the frequencies and amplitudes of the torsional resonance modes of the transmission system varying with engine speed and hydrodynamic torque converter speed ratio are obtained. It is determined that the variable stiffness of the hydrodynamic torque converter has little effect on the natural frequency of the vehicle, and taking variable damping and stiffness as input, the natural frequency and resonance points of the transmission system can be calculated more accurately. The simulation modeling and calculation approach are experimentally verified, and the simulation results are valid and closer to the real resonance.

Torsional and translational vibrations of a eukaryotic nucleus, and the prospect of vibrational mechanotransduction and therapy

Certain eukaryotic cells are believed to sense and respond to vibrational stimuli that are too small even to be transduced by mechanosensitive ion channels. One possible mechanism of signal amplification and transduction is torsional and translational resonance of the nucleus, the stiffest and densest organelle in a eukaryotic cell. To explore this possibility, we developed a theoretical model that analyzes the natural frequencies of torsional and translational vibrations of the nucleus. The model predicts that the natural frequency for torsional vibration is dependent upon cytoskeletal contractility, while that for translational vibration is dependent upon cytoskeletal stiffness. Further analysis across many species and cell types suggests that, for most eukaryotic cells, torsional vibration is the dominant form of nuclear response to higher frequency stimuli, providing a new potential mechanism for frequency-based mechanotransduction.