Combined numerical–experimental model for the identification of mechanical properties of laminated structures

Abstract

A combined numerical±experimental method for the identi®cation of six elastic material modulus of generally thick composite plates is proposed in this paper. This technique can be used in composite plates made of di erent materials and with general stacking sequences. It makes use of experimental plate response data, corresponding numerical predictions and optimisation techniques. The plate response is a set of natural frequencies of¯exural vibration. The numerical model is based on the ®nite element method using a higher-order displacement ®eld. The model is applied to the identi®cation of the elastic modulus of the plate specimen through optimisation techniques, using analytical sensitivities. The validity, e ciency and potentiality of the proposed technique is discussed through test cases. Ó

Structural dynamics of electric machine stators: Modelling guidelines and identification of three-dimensional equivalent material properties for multi-layered orthotropic laminates

“…The works of Watt et al [21], Kamiński and Kleiber [22], and Magalhães Dourado [23] have aimed at identifying composite structures' elastic coefficients by the means of statistical methods, that seem complicated to use in simple, deterministic studies. As for Araújo et al [24], they have proposed a numerical model for the identification of elastic properties of laminates, applied it to the dynamic behaviour of a stratified plate and compared the results with experimental measurements. Yet, this approach does not identify all six lines of Hooke's law elasticity matrix, and is therefore too restrictive to be applied to generic 3D structures.…”

An effectiveness improvement of the inverse technique based on vibration tests

“…It is necessary to note that it was most difficult in the present problem to identify the Poisson's ratio with a high accuracy since a particular aspect ratio of the plate is required in this case. This is well known phenomenon [21] and is related to the lower sensitivities of eigenfrequencies with respect to this design variable. If the desired error level is still not satisfying after the identification technique with the developed methodology has been applied, the sample's imperfections must be introduced into the numerical model or new specimens of higher quality must be prepared.…”

Measurement of relevant elastic and damping material properties in sandwich thick plates

“…Thus, an impulse response h(t) is mathematically represented as a sum of decaying exponentials (natural modes) and measurement noise b(t) as in Eq. (18). Each contribution of a natural mode is characterised by its amplitude A…”

“…The problem of the estimation of solely elasticity parameters of a homogeneous material using plate vibrations has been widely addressed in a thin-plate context [1][2][3][4][5][6][7] and in a thick-plate context [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. In a thin-plate context, only in-plane parameters can be estimated.…”