Resonant-Based Identification of the Poisson’s Ratio of Orthotropic Materials

Abstract

The resonant-based identification of the in-plane elastic properties of orthotropic materials implies the estimation of four principal elastic parameters: E 1 , E 2 , G 12 , and ν 12 . The two elastic moduli and the shear modulus can easily be derived from the resonant frequencies of the flexural and torsional vibration modes, respectively. The identification of the Poisson's ratio, however, is much more challenging, since most frequencies are not sufficiently sensitive to it. The present work addresses this problem by determining the test specimen specifications that create the optimal conditions for the identification of the Poisson's ratio. Two methods are suggested for the determination of the Poisson's ratio of orthotropic materials: the first employs the resonant frequencies of a plate-shaped specimen, while the second uses the resonant frequencies of a set of beam-shaped specimens. Both methods are experimentally validated using a stainless steel sheet.

Mechanical properties of nanocomposite laminated structure and its sensibility to modal analysis procedure

“…The three last mode shapes on Fig. 6 are the best to identify the Poisson's Ratio when they are well defined (Lauwagie et al, 2010). The Poisson Coefficient is related to well-identified experimental coupled mode shapes and good consistency between them.…”

“…The Shear Modulus presented close values for both methods, with the dispersion of values within the expected. The Elasticity modulus depends on, at least, two Latin American Journal of Solids and Structures 11(2014) 245 -259 flexural modes of vibration, on longitudinal and transverse axes, the Poisson's ratio depends on the tree well defined torsion-bending modes, and the Shear Modulus property is linked to the first mode shape, a torsion mode (Ayorinde and Yu, 2005;Lauwagie et al, 2010), that is well defined and of easy measurement and identification. It also seems to be less sensitive to transducer attachment problems.…”

“…Although the great majority of the test specimens for elastic properties determination are square or rectangular plates, there is no direct relation between properties and mode shapes. Mode shapes change according to width to length aspect ratios, fiber or principal axis orientation (Ayorinde and Yu, 2005;Lauwagie et al, 2008), experimental set-up and so on. So a complex structure must be carefully analyzed to take advantage of the best Mode Shapes for the desirable elastic properties.…”

“…This phenomenon could be due to the phase-separated structures and defects in cross-linked structures. For laminated composite and layered structures such as plasma sprayed coatings the vibration technique has proven to be an appropriate method (Lauwagie et al, 2008). The dynamic response of a system depends on geometric and material properties.…”

“…There are various methodologies reported in the literature (Lauwagie et al, 2008;Ayorinde and Yu, 2005;Hwang and Chang, 2000), but all of them use modal analysis for experimental mode identification and employ an optimization method to approximate the actual results to theoretical or Finite Element models. In this work, the procedure proposed by Hwang is used.…”