The objective of the present work is to evaluate the performance of a data-driven approach to simulate a multiphysics vibroacoustic field. Of particular interest is the complex propagation of anechoic waves in a finite 1D-structure submerged in water. Experimental data from an underwater beam actuated by two macro-fiber composites (MFCs) serves as the experimental framework for the data-driven model

Multistability is the phenomenon of multiple coexistent stable states, which are highly sensitive to perturbations, initial conditions, system parameters, etc. Multistability has been widely found in various scientific areas including biology, physics, chemistry, climatology, sociology, and ecology. In a number of systems where multistability naturally exists, it is found to be undesirable because

This note focuses on stability issues of linear time-invariant second-order systems with delayed control input. We provide a computational method to determine the set of purely imaginary characteristic roots which reveals the critical values of frequency and time-delay where the stability switching of the controlled system may takes place. This method requires computing only the solutions of an eigenvalue

The dynamic responses of assembled structures are greatly affected by the mechanical joints, which are often the cause of nonlinear behavior. To better understand and, in the future, tailor the nonlinearities, accurate methods are needed to characterize the dynamic properties of jointed structures. In this paper, the nonlinear characteristics of a jointed beam is studied with the help of multiple identification

Jointed structures are ubiquitous constituents of engineering systems; however, their dynamic properties (e.g., natural frequencies and damping ratios) are challenging to identify correctly due to the complex, nonlinear nature of interfaces. This research seeks to extend the efficacy of traditional experimental methods for linear system identification (such as impact testing, shaker ringdown testing

In order to characterize cutting mechanics during high-speed milling and micromilling applications, high-end piezoelectric dynamometers with a wide frequency bandwidth are necessary. Nevertheless, when installed into the machine tool their signal bandwidth is limited by the dynamic behaviour of the machining system. Thus, special filters have to be adopted for dynamics compensation. State of the art

In the present work, we deal with a dynamical analysis and passive control of chaos with magnetic rheological (MR) rotational damper in a pendulum driven by a DC motor via slider mechanism. A mathematical model for electromechanical system composed of a pendulum driven horizontally by through a DC motor and a slider-crank mechanism is presented and the parameters are estimated based on experimental

FWRVs (Four-way reversing valves) are widely used to switch operating conditions in air conditioner systems. Most previous research focused on the efficiency of the FWRVs in heat pump systems. However, the vibrations during the valve reversing processes are not yet well investigated. The friction-induced vibration (FIV) is generated when the slider slides on the valve seat under the high pressure in

This paper develops a methodology to compute variance-based sensitivity indices for dynamic systems with time series inputs and outputs, while accounting for both aleatory and epistemic uncertainty sources, and both random process and random variable inputs. We present semi-analytical methods for computing sensitivity indices for linear systems with Gaussian random process inputs, and for the general

In this study, self-powered fault diagnosis of rolling bearing (SP-FDRB) is conducted based on the triboelectric effect. Flexible interdigital electrodes are glued to the outer ring of a rolling bearing to form a rolling-type free standing mode triboelectric nanogenerator (RF-TENG). The RF-TENG has adequate service life because it is designed to avoid direct contact between the flexible electrode and

Input estimation is an involved task with wide applications in nonlinear dynamic systems. Model-based input estimation methods are not feasible solutions for problems in which the underlying behavior is not sufficiently known. Data-driven methods have recently shown promise in capturing hidden and subtle nonlinearities in problems from various domains. In this study, we introduce a machine learning

General path models and stochastic process models are two widely applied categories of probabilistic degradation models. The former explains the randomness of degradation data as normal distributed errors with zero mean. The latter describes degradation with stochastic processes such as Wiener process, Gamma process and Inverse Gaussian process. For general path models, a limitation is the assumption

Most of the current approaches and studies in stochastic FE model updating are based on experimental modal data considering updating of uncertain parameters related to stiffness and mass matrices. In many instances, it is desired that the stochastic FE model is able to predict the variability of dynamic response. This calls for identifying the variability of damping matrix also along with variabilities

The diagnosis and monitoring of surface wear are very critical for the prevention of shutdown and even catastrophic destruction of a geared transmission system. However, the detection for the evolutionary status of surface wear in a planetary gear train is quite challengeable due to the complicated and weak characteristics buried in the vibration signals. To assess the wear status of gears in a planetary

The contributions of air-borne tyre noise to the overall interior noise sources of a vehicle were investigated using an acoustic beamforming technique based on the conditioned spectral analysis (CSA). This was realised using a set of accelerometers located at the various sources to measure the reference signals of these sources and, these reference signals were then applied successively in the CSA

The non-contact sensing techniques using image/video processing have flourished in recent years benefited from the rapid development of digital cameras. However, high-fidelity motion extraction from acquired image frames is still challenging. A novel motion estimation method based on phase-domain image processing, named Hilbert phase-based motion estimation, is proposed in this study to identify motions

The galloping energy harvesting technique has been extensively applied to harvest fluid energy and utilize the aeroelastic instability of mechanical systems in a flow field for low-powered electronic devices. However, the flow field is random in the real world. In previous studies, fluid motion was regarded as a deterministic process (i.e., with a constant wind speed). However, to determine the actual

This paper proposes a novel liner stick–slip actuator with compact structure which can achieve forward and backward motion. A novel rhombus-type displacement amplification mechanism (RTDAM) with symmetric structure is used to generate lateral motion to improve the actuator performance. Theoretical analysis and finite element analysis (FEA) are carried out to calculate the coupling ratio and natural

In the work it is proposed a new discontinuous impact model based on the restitution coefficient and the finite duration of the collision, which are functions of the velocity before the collision. The model was validated during modelling, experimental and simulation studies of the bifurcation dynamics of an oscillator of one-degree-of-freedom with a one-sided limiter. The simulation results using the

Video-based measurement has received increased attention for modal analysis and nondestructive evaluation, playing an important role in the development of the next-generation structural sensing technologies. As these techniques have evolved, more quantitative approaches based on computer vision techniques have emerged on full-field unsupervised structural identification, exploiting the benefits provided

This article presents a brief survey on some of the latest developments in the area of reliability-based design optimization of structural systems under stochastic excitation. The contributions are grouped into three main categories, namely, sequential optimization approaches, stochastic search based techniques, and schemes based on augmented reliability spaces. The different approaches are described

Trace identification and detection of toxic, flammable, explosive substances, pollen allergens, as well as biological viruses is crucial for public health and safety, chemic production, and scientific research, etc. A single trace is detectable via various nonlinear resonance phenomena, while quantitative detection of two traces is physically limited by the trace ratio even with localized oscillators

Pedestal looseness and supporting stiffness nonlinearities usually occur in rotating machines. To enhance the robustness and accurately forecast the nonlinear behaviors of rotor systems, these two kinds of common nonlinearities should be considered so that to meet the requirements of the dynamical design of a multi-disk rotor system. In this paper, the rotor system model with cubic supporting stiffness

In recent years, a new research direction in structural condition assessment has been focusing on developing automated or semi-automated procedures to identify a structure’s modal parameters from its response measurements. This is because long-term structural monitoring systems rely on the implementation of system identification methodologies that often involve the intervention of an expert user with

A new receptance method is proposed for partial quadratic pole assignment problem (PQPAP) of asymmetric systems with multi-input. We use receptance matrices of symmetric parts of open-loop systems to express the solution of PQPAP. Then we derive the sensitivities of changed eigenvalues of close-loop system and give the measure of robustness. On these grounds, an algorithm for solving the robust and

Theoretical, numerical, and experimental investigations are presented to predict and suppress the noise radiated from monopole point sources inside an unbaffled long enclosure including the ground. First, a mathematical model is established to calculate the acoustical fields. The modal superposition method is adopted to express the sound pressure inside the long enclosure, while the radiated noise

Operational Modal Analysis allows to assess the modal model of rotating machinery. However, it is needed to pre-process the measured vibration data such that the influence of the harmonic content is suppressed. In this paper, such pre-processing techniques are discussed. The main focus is on evaluating the effects of amplitude modulation, originating for example from speed and load oscillations in

Shear horizontal (SH) waves have received more and more attention in structural health monitoring (SHM) and nondestructive testing (NDT) since the fundamental mode (SH0) is non-dispersive and only has one displacement component, which is very convenient for signal identification and simulation. In recent years, great progress had been made in exciting single-mode SH0 wave for SHM. However, it is still

Minimizing vibration levels of dynamic components at their operating frequency range has been a widely studied topic in engineering. However, the design of structures that satisfy geometric constraints and technical performances is an ongoing challenge. In this work, a topology optimization procedure based on the Bi-directional Evolutionary Structural Optimization (BESO) algorithm is performed to maximize

We investigate two-dimensional phononic metaplates consisting of a periodic array of cups on a thin epoxy plate that is perforated with periodic cross holes. The cups are individually filled with water or remain empty, in view of creating reconfigurable phononic waveguides. Phononic band gaps exist for empty or filled epoxy cups, leading to waveguides defined with either positive or negative contrast

Brake squeal is an important issue in the automotive and railway industry with high frequencies and acoustic pressure (above 1 kHz and 80 dB). For the comfort of passengers, the generation mechanism of this noise needs to be investigated to propose mitigation solutions. Recent works show that the state of the rubbing surface has a strong influence on the occurrences. In this paper, we propose to consider

In this paper, the feasibility of structural health monitoring based on natural frequencies is investigated for a steel bowstring railway bridge in Leuven, Belgium. The data used in the study are obtained from an ongoing long-term monitoring campaign on the railway bridge and include acceleration measurements on the bridge deck and the arches. During the monitoring period, the railway bridge has been

Domain adaptation (DA) as a critical and valuable tool is devoted to minimizing the distribution discrepancy across domains, which has been successfully utilized in intelligent bearing health monitoring. In particular, transfer joint matching (TJM) is a promising transfer learning strategy, especially when the domains differ considerably. In the TJM, the maximum mean discrepancy (MMD) is usually employed

A precise linear-rotary positioning stage (LRPS) for optical focusing based on the stick-slip mechanism was proposed. The proposed positioning stage could realize linear motion along the vertical direction and rotary motion around the vertical direction with both large stroke and high resolution. The configuration and operating principle of the proposed LRPS were introduced. The deflection model of

As one of the most important dynamic characteristic of the widely-used rotating cantilever beams, the centrifugal hardening effect has been extensively studied through theoretical and Finite Element Method (FEM) modeling, but rarely through operational experiments due to the lack of proper measurement techniques. As a result, the previous studies have not been verified convincingly. With the help of

This paper is dedicated to exploring the NASA Langley Challenge on Optimization under Uncertainty by proposing a series of approaches for both forward and inverse treatment of uncertainty propagation and quantification. The primary effort is placed on the categorization of the subproblems as to be forward or inverse procedures, such that dedicated techniques are proposed for the two directions, respectively

This work proposes an efficient algorithm to examine the observability and identifiability of rational nonlinear systems in the presence of unmeasured and unknown inputs. The proposed algorithm allows for determining whether the dynamic states, unknown parameters and unmeasured inputs of a dynamical system can be, in theory, successfully identified from a given set of input–output measurements. The

This paper introduces a novel method for real-time simultaneous input-state-parameter estimation with modulated colored noise excitation. In this method, the unknown inputs are modeled as modulated colored noise, which is realistic for real environmental excitations. By considering this input model, the typical problem of low-frequency drifts in the inputs and displacement responses estimation can

Developing the acoustic-elastic analogy of a topological insulator has attracted extensive research attention in recent years. Designs developed in the literature strongly rely on reforming the host structure of a system to achieve topology transition. In this article, an innovative topological metamaterial is presented. Unlike topological phononic crystals, the proposed topological metamaterial has

The shaft vibration based blade damage monitoring method has become another research focus in addition to tip timing technology because of its simple testing system. However, how to extract the accurate and effective blade damage information from the vibration response of the shaft is the key to the implementation of this method. In this paper, a blade damage monitoring method based on the frequency

High efficiency milling is one of the main goals of CNC machining. Although roughing operation has low requirement for machining accuracy, the milling parameter selection usually need to consider the cutting force, milling stability, spindle torque and power. Besides, the tool wear in difficult-to-cut material machining is another very prominent problem. Therefore, how to achieve the high efficient

In this paper, an origami-inspired vibration isolator is proposed and numerically investigated to achieve a quasi-zero-stiffness (QZS) property. A truss-spring based stack Miura-ori (TS-SMO) structure is introduced in the vibration isolation system to provide a desired stiffness for high-static-low-dynamic requirement. The proposed TS-SMO structure is different from the traditional origami structures

The detection of blade substrate crack is crucial for the safe operation of hard-coated blisk. Due to the coating coverage, it tremendously increases the difficulty of crack size and location detection. This paper presents a novel method based on the mistuning identification technique to detect the blade substrate crack parameters (including crack size and location) for the hard-coated blisk. Different

An elastic gyroscopic rotor system is modelled using the finite element method. The rotor is supported with two piezoelectric actuators which allow a dynamic manipulation of the rotational axis. The piezos are modelled as displacement actuators causing a base excitation. It is known from the literature that actively reducing the displacements of the rotor in the self-centring area leads to increasing

To perform automatic, real-time seam tracking tasks effectively, a robust and accurate seam tracking system must be designed. In this paper, we solve the seam tracking issue using a six-axis welding robot, a line laser sensor and an industrial computer. The processing of welding images is the core of the seam tracking system, which aims to determine the weld feature point in each image. We propose

The natural intermittent impulses created by impeller in case of centrifugal pump, and reciprocating motions of piston in case of axial pump exhibit strong cyclo-stationary phenomenon. This makes the identification of defect impulses difficult in their vibration signals even with the powerful signal processing techniques such as Fast-spectral correlation. To deal with the issue, this work proposes

Obtaining an accurate mathematical model is an important subject to design an overhead crane control system. However, there are some deviations between an existing model and a physical system due to its nonlinearity and complexity characteristics. Motivated by this fact, an adaptive network-based fuzzy inference system (ANFIS) modeling method is proposed for obtaining high precision models. One of

The aim of this study is to investigate the complex damping influences on the oscillatory/static instability characteristics of heated panels in supersonic airflow. Firstly, by assuming a constant, uniform thermal loading and adopting the piston theory, the panel aeroelastic governing equation is obtained. After deriving the panel buckling and vibration modes, the reduced order model can be built and

Bearings are important and easily damaged parts in equipment. Collecting and analyzing the vibration signals of damaged bearings is a common fault diagnosis method. The vibration signal of the damaged bearing under constant speed conditions contains periodic pulses, and may also contain equipment operating vibration information, environmental noise or occasional pulses. In order to extract the periodic

Vibration-based quality monitoring of manufactured components often employs pattern recognition methods. Albeit developing several classification methods, they usually provide high accuracy for specific types of datasets, but not for general cases. In this paper, this issue has been addressed by developing a novel ensemble classifier based on the Dempster-Shafer theory of evidence. In the proposed

Cable-driven robots have great application potentials in confined spaces due to their light and slim bodies. However, their kinematic accuracy is generally much lower than that of the traditional articulated manipulators, because it is difficult to install sensors on its joints to directly measure the joint position. To solve the above problems, this paper proposed a vision-based method for cable-driven

As a result of the research work based on comprehensive numerical and experimental studies, an analytical method for predicting direct action gas difference pressure regulator (DPR) characteristics for dry gas seal (DGS) system allowing to build up from the possible mode of dynamic instability and to ensure the maintenance of required difference pressure for the overall operating range of compressor

Accurately acquiring the geological information of the tunnel face will help to set the optimal operational parameters, so that the shield machine can achieve better tunneling performance. The design of the shield machine prevents the operator from observing the surrounding environment directly, and the soft methods which can utilize machine parameters to recognize geological conditions indirectly

Blind filtering is an emerging topic in various domains to recover an excitation from responses measured by sensors. In the existing literature, the minimum entropy deconvolution is often regarded as the maximum kurtosis deconvolution without providing an underlying connection between them. However, a recent progress towards sparsity measures has shown that kurtosis is actually different from negative