Accurate knowledge of wind turbine tower vibration damping is essential for the estimation of fatigue life. However, the responses in the fore-aft and side-side directions are coupled through the wind-rotor interaction under operational conditions. This causes energy transfers and complicates aerodynamic damping identification using conventional damping ratios. Employing a reduced two-degree of freedom

This paper proposes an automatic tuning algorithm for a sliding mode controller (SMC) based on the Ackermann’s formula, that attenuates the structural vibrations of a seismically excited building equipped with an Active Tuned Mass Damper (ATMD) mounted on its top floor. The switching gain and sliding surface of the SMC are designed through the proposed tuning algorithm to suppress the structural vibrations

Damage detection of civil engineering structures needs to consider the effect of normal environmental variations on structural dynamic properties. This study develops a novel structural damage detection method using factor analysis in the sparse Bayesian learning framework. The unknown changing environmental factors that affect the structural dynamic properties are treated as latent variables in the

The Average-Log-Ratio, ALR, gear-damage detection algorithm is exercised on accelerometer recordings made during earlier-performed accelerated gear testing. Results of ALR computations from tooth bending-fatigue failure and pitting failure are displayed and discussed. The periodic behavior of the rotational-harmonic frequency spectra of tooth working-surface damage is verified and utilized in ALR detection

The dynamic response of gear transmissions holds essential information for the recognition of faults in the system. A realistic nonlinear dynamic model is used to predict the vibration regime of spur gear transmissions. This model was validated experimentally for both healthy and damaged conditions. The model allows to simulate each combination of rotational speed, load and surface roughness, and to

We formulate the control problem of active suspension systems (ASSs) that are underactuated as constraint-following. The objective is to drive the system to follow a series of servo constraints or control goals which include both equality constraint of the reference trajectory and inequality constraint of the boundary restriction on the sprung mass displacement. The equality constraints may be holonomic

This paper derives a formula to determine the minimum detectable damage based on ambient vibration data. It is a key element to analyze which damage scenarios can be detected before a monitoring system is installed. For the analysis, vibration data from the reference structure as well as a finite element model are required. Minimum detectability is defined by adopting a code-based reliability concept

Qualification tests on the vibrations of on-board equipment depend on the ability of the shaker used to reproduce as precisely as possible the excitation profiles stipulated by standards, given that real operational conditions are generally multiaxial. Using a set of six measured linear accelerations the original method proposed permits determining real six-axial shaker displacements combining three

The accurate localization of low-velocity impacts on the composite plate structure of the ship is still a great challenge. Current research mainly focuses on extracting single domain features from impact signals as the input of machine learning methods, whereas ignores multi-domain features with more comprehensive impact information. In this paper, a hybrid support vector regression with multi-domain

This study presents the nonlinear modeling and model predictive control of a new semi-active hydro-pneumatic inerter-based suspension system (SAHPISS) for the first time. Unlike the traditional semi-active hydro-pneumatic suspension, a fluid inerter is added to the semi-active hydro-pneumatic suspension and a better damping effect can be achieved by adjusting the opening of the hydraulic control valve

A novel two-axis piezoelectric tilting mirror (PETM) was proposed for optical assisted micromanipulation, which avoided the shortcomings of high capacitance, relatively high cost and complex structure of general multi-axis steering mirrors using piezoelectric ceramic stack actuator. The developed PETM realized two-axis tilting motions via a simple bonded-type piezoelectric composite beam. The parametric

A designated set of shape functions are created for cylindrical shell structures. The 1D Chebyshev polynomial is applied along the axial direction and the 1D harmonic basis along the circumferential direction. A 2D orthogonal space is formed on the cylindrical domain by combining the above two 1D bases and is used to develop the expansion function. A finite element model is not required for the expansion

Using three actuators for tracking five outputs, rubber-tired gantry (RTG) crane is found to be a highly under-actuated system subject to random wind due to working outdoors. Applying fractional calculus to sliding mode control (SMC), we construct an adaptive robust control system for RTG cranes under parametric variations and unknown wind. The adaptive feature is achieved by using an estimation mechanism

Rotating machinery signals are usually dominated by rotating frequency harmonics, and the presence of these frequency components or change in their magnitudes indicate health condition. Order spectrum is widely applied in rotating machinery fault feature extraction, because of its capability in intuitive spectral representation of rotating frequency harmonics in order domain. However, some speed non-synchronous

This paper presents a new Bayesian approach to equation discovery – combined structure detection and parameter estimation – for system identification (SI) in nonlinear structural dynamics. The structure detection is accomplished via a sparsity-inducing prior within a Relevance Vector Machine (RVM) framework; the prior ensures that terms making no contribution to the model are driven to zero coefficient

This paper proposes a k-Nearest Neighbours (kNN) algorithm for locating and quantifying bridge damage based on the time-varying forced frequencies due to a moving truck. Eigenvalue analysis of a simplified vehicle-bridge coupled system, consisting of a three-axle rigid truck model and a simply supported finite element beam model, shows how the eigenfrequencies of the coupled system vary with the locations

The main purpose of this paper is to represent a methodenabling vibration components to be extracted from a high-resolution Short-Time Fourier-Transformation (STFT) based spectrogram assessed as an image to support transient analysis on rotating machines. Therefore, an improved STFT algorithm was developed to allocate and utilize computational memory more efficiently. The resulting spectrogram was

The purpose of this study is to develop an acceleration-strain conversion model that considers torsional strain and spring curvature effects in inducing strain for a suspension coil spring. Measurements of strain–time histories at the coil spring are limited by complex geometry and insufficient workspace. This condition increases the demand for strain signal generation through multibody dynamics (MBD)

In a practical production environment, machinery operators would consider using contactless sensing technology to monitor machinery degradation condition due to the concern of interference on production. A stream of time-series infrared images as a contactless sensing technology could capture the spatial and temporal information of a machinery degradation process. However, due to four dimensions (4D)

Effectively identifying the health status of rolling bearings can reduce the maintenance costs of rotating mechanical components. With the development and improvement of various signal processing theories, the mode of extracting fault information from the frequency domain has gradually replaced the mode from the time domain. As a traditional spectrum segmentation analysis method, Fast Kurtogram can

The integration of plain journal bearings (JBs) and active magnetic bearings (AMBs) has previously been introduced as an innovative bearing concept in rotating machinery, known as smart electro-mechanical actuator journal integrated bearings (SEMAJIBs). The integrated bearing system tends to exploit the advantages and eliminate the deficiencies of each individual bearing technology. However, the integration

We study the dynamics of two pendulum clocks suspended on a swinging support, investigating the scenarios of symmetrical and asymmetrical geometry of the oscillators’ suspension. The regions of possible dynamical patterns are determined and typical behaviours of the system are described. We show, that depending on the parameters and the initial conditions, multistable synchronous states can arise,

This paper proposes a simple and a robust bistable docking system with a deep learning based real-time drogue detection and tracking system for Unmanned Aircraft Systems (UAS) for mid-air autonomous aerial docking. Secure aerial docking mechanisms between the leader and follower aerial vehicles with effective drogue detection and tracking strategies are fundamental challenges during the air-to-air

Torsional piezoelectric actuators have been widely applied in many fields due to their specific vibration mode. However, the conventional torsional vibration piezoelectric actuators require circumferentially polarized piezoelectric ceramics or special structural designs, increasing manufacturing difficulty and processing costs, and seriously limiting their applications. In order to solve these problems

Grinding force is a crucial factor that affects the machining accuracy, wheel wear and the material removal efficiency for precision machining of semiconductor materials under nanometer accuracy. However, due to the complex rotational motion of both the grinding wheel and wafer workpiece, in situ measurement of the grinding force in wafer self-rotating grinding is still a big challenge. In this paper

In this work, we implement a framework for adjusting the outputs of a torsional vibration damper (TVD) model to experimental data using physics-informed neural networks. TVDs are devices used to passively control vibration; and here are commonly modeled through reduced-order physics. Within the TVD model, the material properties of the viscoelastic rubber used in the device are characterized through

The study of mono-coupled periodic structures has gained renewed interest by the scientific community due to the new applications of metamaterials and meta-structures. Much research has focused on the wave propagation properties of infinite structures. However, this paper focuses on finite periodic structures, in particular the parameters that govern the behaviour of a low frequency stop-band of such

This paper proposes a novel localization method of simultaneous two acoustic emission (AE) sources to decouple the two coupled AE waves in the structure and obtain more accurate localization results by means of frequency-domain notch-weighted beamforming. Firstly, the notch-wave theory is analyzed and combined with propagation characteristics of AE waves to derive the mechanism and method of the frequency-domain

Hysteresis phenomenon limits the effective use of pneumatic artificial muscles in numerous driving applications. Experimental results show widening hysteresis loops and lowering displacement amplitudes by increasing excitation frequency. In this study, a feedforward controller is proposed to compensate for this hysteretic behavior. This proposed controller is based on a rate-dependent Prandtl–Ishlinskii

In this paper the double and triple-frequency synchronization of the two co-rotating exciters, in a far super-resonant vibrating system, are analyzed by theory, numeric, simulation and experiment. The motion differential equations of the system are given firstly. The theoretical conditions of implementing double/triple-frequency synchronization, are deduced by introducing the asymptotic method and

As one of the crucial subsystems, the performance of the wheelset-bearing system will significantly affect the running safety, stability and comfort of a high-speed train. Compared with the traditional rotating machinery vibration signals, those of wheelset-bearing systems have a distinct difference, for instance, the wheelset tread damage induced vibrations and bearing fault-related vibrations coexist

Aiming to detect the weak rail crack signal under strong Wheel-rail Rolling Noise (WRRN) in high-speed railway by Acoustic Emission (AE) technology, a Hurst exponent-improved Adaptive Line Enhancer (ALE) is put forward. The Hurst exponent is adopted to describe the irregularity and fractality property, and is introduced into the cost function of ALE through its power-law relation with the structure

A procedure is presented to identify the nonlinear damping and stiffness parameters of a single-degree-of-freedom (SDOF) model from large-amplitude vibrations of harmonically forced continuous systems, in absence of internal resonances. Cubic nonlinear damping is introduced in the SDOF model in addition to the classical viscous one. The parameter estimation relies on the harmonic balance method. It

In this paper, a single-degree-of-freedom dynamic model is described, with displacement- and velocity-dependent nonlinearities represented by power laws. The model is intended to support the dynamic identification of structural components subjected to harmonic excitation. In comparison to other analytical expressions, the data-driven estimation of the nonlinear exponents provides a large versatility

In the scenarios of high-speed operation, the bad elastic vibrations of lightweight manipulators readily arise, thus affect the overall motion of system even induce motion instability, which is a critical issue needing to be tackled appropriately. This paper concentrates on the efficient dynamic modeling and tracking/vibration integrated control for a lightweight parallel manipulator (LWPM) including

Continuous generating gear grinding is a well-established and widely used process in the industry for large-scale production gears. It offers an economic/efficient process for finishing gears, which shapes the micro-geometry of the gear tooth flank and improves its surface quality. The resulting quality of ground gears depends on several factors, namely the tool performance, the machine stability as

Demodulation analysis is one of the most effective methods for bearing fault diagnosis. However, in practical applications, the interferences from ambient noises or other rotating components may create great challenges to demodulation analysis and thus decrease its effectiveness. Generally, a selection procedure for the most informative frequency band (IFB) is usually implemented in advance to extract

Automatic inspection methods based on machine vision have been widely employed for steel surface defect detection. The central purpose of these methods is to extract features to represent different defects. However, current methods depend on machine learning that demands handcrafted features and overlooks the domain shift. In this paper, we propose a new method combining domain adaptation (DA) and

The recently developed Wiener path integral (WPI) technique for determining the stochastic response of diverse nonlinear systems relies on solving a functional minimization problem for the most probable path, which is then utilized for evaluating a specific point of the system joint response probability density function (PDF). However, although various numerical optimization algorithms can be employed

Zero-memory non-linear (ZMNL) methods have long been a type of very useful tools in creating super-Gaussian random excitations for fatigue test. The major drawback of this method is that the magnitude distortion can be seen in both auto-power spectral density (ASD) and cross power-spectral density (CSD) of the excitation if the dynamic range of the target power spectral density (PSD) is large. To study

Recent studies on plate-type metastructures have shown promising applications in low-frequency sound insulation, as they possess a low-frequency sound transmission loss (STL) that is considerably higher than that derived from the mass law. To design a plate-type metastructure for a sound insulation application, three problems are worth exploring: 1) how to predict efficiently the STL of the metastructure

This paper presented a non-linear modeling approach for bolted joint connection interfaces and identified the micro-slip model’s parameters through quasi-static experiments based on an improved micro-slip model. Firstly, considering the contact pressure’s spatial distribution characteristics on the connection interface, a new density function of critical sliding force was proposed. The contact pressure

Fault identification in hydraulic valves is essential in maintaining the reliability and security of hydraulic systems. Due to the nonlinear characteristics of hydraulic systems under noisy working conditions, it is difficult to extract fault features from vibration signals collected from the surface of the valve body. Therefore, a DSmT-based three-layer method using multi-classifier is proposed to

Linear systems are frequently encountered in low, mid and high vibroacoustics modelling of mechanical built-up structures. It has recently been proved that the solution to those systems can be always factorized as an infinite (weighted) Neumann series summation, which accounts for signal transmission through paths connecting system elements. The key to path expansion relies on the concept of direct

The polygon wear of railway wheel (PWRW) is a wear fault that is ubiquitous in railway vehicles. PWRW can induce a strong periodic excitation to both vehicle and track, which not only decreases passenger comfort but also is detrimental to the operational reliability and safety. Both the degree and the order of PWRW are important parameters used to quantify the fault. Because the fault-related components

Nonlinear forces have been widely introduced into vibration energy harvesting to improve its performance. Generally, sources of nonlinearity include magnet forces, spring forces, geometric and material nonlinearity, etc. However, these nonlinear forces cannot be manipulated arbitrarily. It is very promising if the nonlinear forces can be customized according to requirements, in which the performance

Industrial machinery is often equipped with proximity probes that measure continuously position and vibrations of the shaft, generally relative to the bearings. These measurements are used for surveillance of the machine, and furnish valuable information to be used in a diagnostic process, especially when run-up or run-down transients are recorded and processed. However, a question arises, during normal

This paper investigates a new finite-time fault-tolerant control (FTC) using a fractional-order backstepping iterative design strategy for a fixed-wing unmanned aerial vehicle (UAV) in the presence of actuator faults and input saturation. To compensate for the lumped disturbance induced by the actuator faults, a neural network disturbance observer (NNDO) with finite-time observation capability is first