Modal testing

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

EEMD-MUSIC-based analysis for natural frequencies identification of structures using artificial and natural excitations.

Abstract: This paper presents a new EEMD-MUSIC- (ensemble empirical mode decomposition-multiple signal classification-) based methodology to identify modal frequencies in structures ranging from free and ambient vibration signals produced by artificial and natural excitations and also considering several factors as nonstationary effects, close modal frequencies, and noisy environments, which are common situations where several techniques reported in literature fail. The EEMD and MUSIC methods are used to decompose the vibration signal into a set of IMFs (intrinsic mode functions) and to identify the natural frequencies of a structure, respectively. The effectiveness of the proposed methodology has been validated and tested with synthetic signals and under real operating conditions. The experiments are focused on extracting the natural frequencies of a truss-type scaled structure and of a bridge used for both highway traffic and pedestrians. Results show the proposed methodology as a suitable solution for natural frequencies identification of structures from free and ambient vibration signals.

Modal sampling method for the vibration study of systems of high modal density

Abstract: This paper presents a method to predict the vibration response of a group of modes, using a sample of modes of the group. The accuracy of the prediction can be improved when increasing the size of the sample. Numerical calculations made on a beam, driven in longitudinal motion, show the ability of the method to reconstitute the energy response of a group of modes including resonant modes, with a sample of a number of modes close to that in the effective damping bandwidth.

Modal Characteristics of a Flexible Smart Plate Filled with Electrorheological Fluids

Abstract: This paper presents modal characteristics of a flexible smart plate filled with an electrorheolo gical fluid. First, an oscillatory test is undertaken to extract the electric field-dependent complex shear modulus of the employed starch/silicone oil-based electrorheological fluid. A dynamic model of the smart plate associated with the measured modulus is then developed by adopting a finite element approach to predict field-dependent modal characteristics. Following the construction of a four-partitioned smart plate, an extensive modal test is empirically conducted to identify natural frequencies and mode shapes with respect to both the intensity and the area of the applied field to the fluid domains. Consequently, the measured natural frequencies and mode shapes are compared with the predicted ones to validate the proposed dynamic model. In addition, the control effectiveness for different field-energizing areas under the forced vibration is evaluated in the time domain.

Determination of Stiffness Changes from Modal Parameter Changes for Structural Health Monitoring

Abstract: A Bayesian probabilistic methodology is presented for identification of structural stiffness loss from changes in estimated modal parameters. The method constitutes the second step of a two-step procedure for continuously monitoring the health of a structure by utilizing its natural ambient vibrations. The version presented here assumes that any damage that occurs is localized to one part of the structure. Numerical testing of the proposed scheme shows that under specified conditions, the method successfully determines the existence, location, and degree of stiffness loss, even in the presence of levels of uncertainty in the estimated modal parameters that are expected in real applications.