ON THE DETERMINATION OF DYNAMIC PROPERTIES OF RESILIENT MATERIALS USING A MULTI-LAMINATED PERIODIC SPECIMEN

Multilayered materials consisting of elastic and viscoelastic layers are crucial for the control of noise and vibration originated from structural sources. Cork and cork-rubber are examples of such materials, which we have been using and studying. Due to the viscoelastic character of cork and cork agglomerates, the static modulus of elasticity may differ substantially from the storage modulus; therefore, the former should not be used in most dynamic analysis. This study presents an experimental characterization of the dynamic modulus of elasticity of cork agglomerates and may be divided into two parts. In the first part, a multilayered periodic bar specimen using alternate layers of cork agglomerate and steel is used. In the second part, a procedure following the ISO 9052-1 norm is performed on rectangular specimens. A harmonic excitation is applied to the specimens to obtain the first natural frequency from which the dynamic stiffness and loss factor are estimated. The results obtained are verified numerically through finite element analysis and show that the multi-laminated periodic bar may be used to experimentally obtain a satisfactory estimate of the dynamic modulus of cork agglomerate.