Modal testing

About: Modal testing is a research topic. Over the lifetime, 4047 publications have been published within this topic receiving 64772 citations.

Finite element model updating using bees algorithm

Abstract: In this paper the application of bees algorithm (BA) in the finite element (FE) model updating of structures is investigated. BA is an optimization algorithm inspired by the natural foraging behavior of honeybees to find food sources. The weighted sum of the squared error between the measured and computed modal parameters is used as the objective function. To demonstrate the effectiveness of the proposed method, BA is applied on a piping system to update several physical parameters of its FE model. To this end, the modal parameters of the numerical model are compared with the experimental ones obtained through modal testing. Moreover, to verify the performance of BA, it is compared with the genetic algorithm, the particle swarm optimization and the inverse eigensensitivity method. Comparison of the results indicates that BA is a simple and robust approach that could be effectively applied to the FE model updating problems.

Experiments in piezostructure modal analysis for MIMO feedback control

Abstract: An approximate method for modal analysis of a piezostructure testbed is used to generate a dynamic model for closed-loop, multiple-input-multiple-output (MIMO) feedback controller design. An innovative pole-residue system model for structures instrumented with piezoelectric sensor and actuators is developed which is compatible with existing modal curve-fitting algorithms. The authors examine the use of the new pole-residue model in the absence of truly collocated response information. It is shown that nearly-collocated measurements may be used to estimate a structure's modal parameters; high-precision signal conditioning electronics required for exact drive-point response measurements are thereby avoided. A simply-supported plate is used to demonstrate the approximate piezostructure modal test approach. The test model is then used to design up to a four input, sixteen channel output MIMO feedback control experiment. Closed-loop results are presented which show that more than 10 dB of suppression is achieved near structural resonances within the control bandwidth (10-250 Hz).

Earthquake structural modal estimates of multi-storey frames by a refined Frequency Domain Decomposition algorithm

Abstract: This paper targets the frequency domain identification of current structural modal properties under earthquake excitation. A new refined Frequency Domain Decomposition (rFDD) algorithm is implemented towards the output-only modal dynamic identification of heavy-damped frame structures, which are subjected to a wide set of strong ground motions. In fact, both seismic excitation and/or high damping values shall not fulfil traditional FDD assumptions. Despite that, with the present rFDD implementation quite limited errors in the modal parameter estimates have been achieved, including for the modal damping ratios (ranging from 1% to 10%). At first, the identification technique is formulated and explored analytically, by proving its potential effectiveness with seismic response input. Then, all strong motion modal parameters are consistently identified. As a fundamental necessary condition, synthetic response signals are adopted. These have been generated prior to dynamic identification from computed numerical...

Estimation of modal correlation coefficients from background and resonant responses

Abstract: A new simple relation for the estimation of modal correlation coefficients is presented. It is obtained from the decomposition of covariances of modal responses into background and resonant contributions, as it is commonly done for the variances. Thanks to appropriate assumptions, the modal correlation coefficients are estimated as weighted sums of two limit values, corresponding to the background and resonant responses respectively. The weighting coefficients are expressed as functions of the background-to-resonant ratios, which makes the proposed formulation convenient and easily accessible. The simplicity of the mathematical formulation facilitates the physical interpretation. It is for example proved that modal correlation coefficients can be non negligable even in case of well separated natural frequencies, which is sometimes unclear in the litterature. The new relation is mainly efficient in case of large finite element models. It is applied and validated on a finite element buffeting analysis of the Viaduct of Millau, the highest bridge deck ever built so far.