Showing papers in "Mechanical Systems and Signal Processing in 1990"

TL;DR: The restoring force methods of system identification, which include the Masri/Caughey procedure, require the simultaneous measurement of acceleration, velocity and displacement data.

TL;DR: In this article, a general method using frequency response functional (FRF) is developed for reanalysing a structure subjected to structural modification, which can be expressed in terms of additional mass, stiffness and damping matrices.

TL;DR: Whether a careful choice of excitation signal can minimise the amount of data processing required for restoring force methods of non-linear system identification is concerned with.

TL;DR: In this article, a modal identification technique for the dynamic behavior of linear time-invariant systems is presented, using a state space formulation for the equations of motion for a mechanical structure, an algorithm is developed to identify its state transition matrix from measured multiple input/multiple output relations (frequency response functions).

TL;DR: In this paper, the frequency response functions have been used directly to update condensed analytical models and so avoid the sometimes difficult step of deriving the modal model, which is the system natural frequencies, damping coefficients and mode shapes.

TL;DR: The algorithms derived in Part I are applied to estimate the generalised frequency response functions of two unknown real systems and the results are interpreted using the techniques developed in Part II of the study.

TL;DR: In this paper, a unified identification theory for non-linear systems which can be represented by cascade, multiplicative and feedback connections of linear dynamic and static nonlinear subsystems is presented.

TL;DR: In this paper, the authors compared two earlier approaches by the present author and presented a new approach according to Pareto's distribution for the determination of limit values and the mean life-curve.

TL;DR: In this paper, the results of an experimental study of a T-beam structure for the well separated bending and torsion modes are presented for the force state mapping approach to the identification of non-linear structures.

TL;DR: In this paper, the authors describe the design and implementation of a digital integrator which is used in a control system to modify the structural frequency response of a cantilever beam.

TL;DR: In this paper, an auto-regressive model and the corresponding processes of feature extraction and condition monitoring are investigated in detail, and an orthogonal transformation is introduced for both feature compression and the establishment of a statistical model of the template representing the normal condition.

TL;DR: In this article, it is shown that it is possible to estimate the complete physical state of the system by using only measurements at a few available points in combination with the mathematical model.

TL;DR: In this paper, a parametric maximum likelihood estimator (MLE) in the frequency domain for multi-input, multi-output (MIMO) systems is given, taking into account the perturbation noise on all the measured input and output signals.

TL;DR: The finite element model updating process developed at ONERA is based on the minimisation of input errors in the dynamic equilibrium equations as discussed by the authors, where reaction forces due to incorrect stiffness or mass matrix of the model are used to localise the predominant errors and, afterwards, to find correcting parameters, in order to have a prediction model as close as possible to the real structure.

TL;DR: In this article, a design sensitivity analysis method for linear quadratic Gaussian (LQG) optimal control laws is presented, enabling the use of LQG techniques in the hierarchal design methodology.

TL;DR: Recommendations to improve overall computational accuracy are given and are easily realisable using more powerful microcomputing equipment than the one used here.

TL;DR: It is shown why structural modifications are unable to increase the life of the structure unless the frequency contents of the load input is altered, the lifetime remains unacceptably low and the only modification that is able to increased the lifetime significantly is the choice of a material with better fatigue properties.

TL;DR: In this paper, five global time domain parameter estimation methods, least squares, double least square, total least square and correlation fit, were compared using the same set of impulse responses taken from the ground vibration test of an aircraft structure.

TL;DR: Upper and lower bounds for the eigenvalues of a modified structure based on truncated modal testing results are given and it is shown that for the given information the upper bounds are the least upper bounds, while the lower limits are the greatest lower bounds.

TL;DR: In this paper, a method of structural dynamic optimisation has been applied to a complex engineering structure e.g. a high speed machining center, where the physical structural changes which yield specified dynamic requirements at a minimum cost are determined.

TL;DR: In this paper, a new technique combining principal components analysis and autoregressive spectra (PCAT) is introduced to diagnose rub failure between rotating and stationary parts using only ordinary FFT spectra or auto-regressive spectra.

TL;DR: In this paper, a new method to identify the moment and radial stiffness and damping coefficients of isotropic bearing in a spindle bearing system with incomplete mode shapes is proposed.

TL;DR: In this paper, a method is presented for predicting the impact force between a mass of known velocity and a structure using measured frequency response functions to characterise the dynamics of the underlying structure and a Hertzian model of the local contact stiffness at the point of impact.

TL;DR: In this article, it is shown how the pattern of discrepancies in analytical and experimental test values for the pole and the driving point zero frequencies of a structure can be linked to discrepancies in the mass or stiffness of the structural elements.

TL;DR: In this article, some new indices in the sequency domain are defined describing the vibroacoustical process of machinery based on the fast Walsh transform, which is a useful index for detecting the change of power spectral components but it cannot be obtained easily and quickly.

TL;DR: In this article, the spectral shape of the response near the natural frequency is estimated first as the basis for further analysis, the bandwidth and spectral moments are subsequently related to the damping ratio.

TL;DR: In this article, the effect of machine vibroisolation on the dynamic forces acting through bearings is investigated, and a design relation has been determined which satisfies the vibration isolation condition, and simultaneously decreases the dynamic load of the bearings.

TL;DR: In this article, the problem of using a force input to a structure which consists of the sum of sinusoids is considered, and an algorithm to calculate these phases and examples of typical force input signals are given.

TL;DR: In this paper, a symmetric, non-recursive digital filter is used to investigate the effect of prefiltration of data on the variance of spectral estimates derived from randomly sampled signals.