Dynamic Determination of the Modulus of Elasticity of Maritime Pine Cross-Laminated Panels Using Vibration Methods

Abstract

This paper describes the preliminary results of an ongoing research activity involving Maritime Pine Cross-Laminated Timber (CLT) panels, aimed to exploit the potentialities of this native species of Sardinia. The modulus of elasticity (MOE) is a key parameter for grading wooden products and evaluating the overall mechanical properties of panels. Free Vibration tests can be an effective method to assess the dynamic MOE of wooden products; the method is based on the direct measurement of the first vibration mode frequency of the specimens and the indirect determination of the elastic parameters. The present work shows a straightforward approach to evaluate the dynamic MOE of cross-laminated panels by choosing suitable boundary conditions depending on the specimen sizes. For this purpose, various experimental tests were conducted on different configurations aiming to evaluate the dynamic MOE for the considered cases. Furthermore, the relationship between global vibrational behaviour of panels and original boards MOE has been investigated. The dynamic MOE obtained by vibration testing method has been compared with the static MOE evaluated by bending tests in order to find a correlation. A linear relationship between dynamic and static MOE was found, with the dynamic MOE being slightly higher than the static MOE, as expected. The dependence of the correlation upon the applied methodology was determined and regression equations were derived and are provided in the paper.

Use of the cantilever beam vibration method for determining the elastic properties of maritime pine cross-laminated panels

“…Nevertheless, as a comparison tool, a free vibration approach based on Euler-Bernoulli beam theory is discussed in Section 2.1. The comparison between classic beam theories and FE models can be a useful mean for understanding the limits of the Euler-Bernoulli beam approach [16] often employed in dynamic identification techniques [41,43] and in structural design of timber construction.…”

“…where E0 (Pa) is the dynamic MOE of the panel parallel to the grain orientation of face boards, f (Hz)is the panel first natural vibration frequency, M (kgf) is the weight of the specimen, L (m) is the length of the panel, I (m 4 )is the cross-section effective moment of inertia with respect to the centroid, while l (m) denotes the effective span of the cantilever [16,43]. The panel MOE can therefore be easily evaluated through an experimental determination of the first natural frequency.…”

“…In recent years researchers have focused the attention on non-destructive techniques [38][39][40] and several dynamic testing methods have been proposed for the determination of both elastic and shear moduli of wood composite panels. Dynamic testing has been proved to be an effective procedure for performing elastic identification of CLT panels [41][42][43] and cantilever beam vibration methods have been listed as reliable approaches in [42,43]. Nevertheless, these approaches are usually based on a Euler-Bernoulli beam analysis [41], which can lead, as illustrated in [41,44], to systematic errors in evaluating the CLT panel elastic modulus E0, and to disregard the role of shear deformations.…”

CLT Fabricated with Gmelina arborea and Tectona grandis Wood from Fast-Growth Forest Plantations: Physical and Mechanical Properties

“…CLT was developed in Europe during the 1970s; since then it has been manufactured by many species and softwood is used in many countries [7][8][9]. Furthermore, cross laminating used in CLT panels grants improved dimensional stability, reduces the dispersion of the wood's properties and reduces the influence of the defects, while increasing rigidity in the parallel and perpendicular planes [10]. Compared to other construction materials, CLT panels offer good seismic resistance [11], diminish assembling time [12] and allow the application of fire retardant treatments [13] or treatments to avoid damage due to fungi or insects [14].…”

Experimental and Numerical Investigations into Dynamic Modal Parameters of Fiber-Reinforced Foamed Urethane Composite Beams in Railway Switches and Crossings

“…In fact, the base of the ASTM criterion [26] test method to characterize dynamic elastic properties was set by those researchers, using the impulse excitation technique [27]. To date, several researchers have investigated the estimation of the elastic properties of laminated composites [28][29][30][31][32][33], timber materials [34,35], or concrete materials [36], which are non-isotropic and/or inhomogeneous, using vibration-based approaches. It is important to note that the standard tests for dynamic properties gain significant supports from scientific and engineering communities in present days.…”