Showing papers in "Mechanical Systems and Signal Processing in 2008"

TL;DR: In this article, two types of features are extracted from the measurements: eigenproperties of the structure using an automated stochastic subspace identification procedure and peak indicators computed on the Fourier transform of modal filters.

TL;DR: In this paper, the variance estimation procedure uses the first-order sensitivity of the modal parameter estimates to perturbations of the measured output-only data, which is applicable for the reference-based covariance-driven stochastic subspace identification algorithm.

TL;DR: In this paper, a procedure for the investigation of local damage in composite materials based on the analysis of the signals of acoustic emission (AE) is presented, where unsupervised pattern recognition analyses (fuzzy C-means clustering) associated with a principal component analysis are used for the classification of the monitored AE events.

TL;DR: In this paper, the use of the combined deterministic-stochastic subspace identification algorithm for the experimental modal analysis of mechanical structures is discussed The algorithm requires artificial forces to be applied to the structure, so it can also be used for operational modality analysis (OMA), since the excitation level of the artificial forces can be low compared to the ambient forces.

TL;DR: In this paper, the authors present a simulation model for a gearbox test rig, in which a range of bearing faults can be implemented, including inner race, outer race and rolling elements.

TL;DR: In this article, the authors developed a novel energy harvesting backpack that can generate electrical energy from the differential forces between the wearer and the pack by replacing the strap buckle with a mechanically amplified piezoelectric stack actuator.

TL;DR: The diagnosis result shows the algorithm is able to reliably recognise not only different fault categories and severities but also the compound faults, and demonstrates the superior effectiveness and practicability of the algorithm.

TL;DR: In this paper, a statistical classification algorithm is presented based on analysis of a structure's response in the time domain, which is fitted with Autoregressive Moving Average (ARMA) models and the ARMA coefficients are fed to the classifier.

TL;DR: In this article, an empirical mode decomposition (EMD) based approach for rotating machine fault diagnosis is investigated, which is a new time-frequency analyzing method for nonlinear and non-stationary signals.

TL;DR: In this paper, the strain energy release rate (SERR) theory is applied to a rotating crack and gives good results, and different methods of crack identification are presented as well as those for multi-crack identification.

TL;DR: In this article, a multiscale morphology analysis is applied to one-dimensional signal by defining both the length and height scales of structuring elements (SEs) and a local-peak value based adaptive algorithm is also introduced.

TL;DR: In this paper, the problem of model updating in the presence of test-structure variability is addressed and two perturbation methods are developed for the estimation of the first and second statistical moments of randomised updating parameters from measured variability in modal responses (e.g. natural frequencies and mode shapes).

TL;DR: In this paper, a multistage scheme for damage detection for large structures based on experimental modal data and on finite element (FE) model updating methods applied on simple FE models is proposed.

TL;DR: The results show that this use of SSA and cluster analysis provides an efficient automatic signal processing method, and that the proposed TCMS, based on this procedure, is fast and reliable for tool wear monitoring.

TL;DR: A new damage identification technique based on the statistical moments of the energy density function of the vibration responses in the time-scale (or time-frequency) domain that is more sensitive to damage than existing non-model-based damage identification techniques.

TL;DR: In this paper, the authors summarize the different studies on double/multi-cracks and to note the influences, identification methods in vibration structures such as beams, rotors, pipes, etc.

TL;DR: In this paper, a second-order statistical method employed in blind source separation (BSS) is adapted for use in modal parameter identification, and a class of new non-parametric output-only modal identification algorithms is proposed and examples of its use are provided.

TL;DR: In this paper, the authors proposed new and simple indicators of cyclostationarity for the characterisation of vibration signals whose statistics are periodically varying with respect to some generic variable, and their statistical properties were derived.

TL;DR: In this article, a combined dynamic model for gears and bearings is presented, in which an extended fault in the inner/outer race of rolling element bearings can be studied in the presence of gear interaction.

TL;DR: In this article, a method that uses nonlinear Lamb waves to detect material nonlinearity is presented, which is well suited for the interrogation of thin metallic layers which act as waveguides, giving Lamb waves great potential in non-destructive evaluation applications.

TL;DR: In this article, the impact of axial displacement/load on bearing excitation has been investigated in the case of spherical roller bearing (SRB) systems, and a detailed contact-damping model reflecting the influences of the surface profiles and the speeds of the both contacting elements is developed.

TL;DR: In this paper, a numerical simulation of a two-stage reciprocating compressor has replicated the operations of the compressor under various conditions for the development of diagnostic features for predictive condition monitoring.

TL;DR: In this article, a new de-noising scheme is proposed to enhance the vibration signals acquired from faulty bearings. But, when bearings are installed as part of a complex mechanical system, the measured signal is often heavily clouded by various noises due to the compounded effect of interferences of other machine elements and background noises present in the measuring device.

TL;DR: In this paper, a robust fuzzy sliding mode control (FSMC) scheme for the synchronization of two chaotic nonlinear gyros subject to uncertainties and external disturbances is presented, where the reaching law required to drive the error state trajectory of the master-slave system to the sliding surface is inferred by a set of fuzzy logic rules based upon the output of a sliding mode controller.

TL;DR: In this article, a method in the time domain for the identification of nonlinear vibrating structures is described, which allows to estimate the coefficients of the nonlinearities away from the location of the applied excitations and also to identify the linear dynamic compliance matrix when the number of excitations is smaller than number of response locations.

TL;DR: In this article, the authors investigate the cycle-to-cycle pressure variations for six rotational speeds of the crankshaft of a diesel engine and find that depending on the speed of rotation, the pressure variations may have a strongly periodic component and/or be intermittent.

TL;DR: An approach to this problem using vibration data, which involves the development of a data-based model using an auto-regressive moving average model, and the classification of whether or not the structure is damaged using a fuzzy clustering approach.

TL;DR: In this paper, a one disc rotor (Laval rotor) with a transverse crack in the elastic shaft is analyzed and a simple crack model is derived with the aid of a simple model of non-linear equations of motion.

TL;DR: In this article, a structural health monitoring system based on PZT transducers is presented, taking advantage of spectral element method simulations of A0 mode of the Lamb waves propagating in a multilayer composite plate.

TL;DR: It is shown that the load identification and thus also the subsystem identification is sensitive to the existence of general anti-resonances in the frequency domain of interest and the methods for validation of an identified subsystem are discussed.