1. EXPERIMENTAL MESUREMENTS OF THE DYNAMIC PROPERTIES OF VISCOELASTIC MATERIALS AND SYSTEMS Imeko Technical Committee 15 2nd Youth Symposium on Experimental Solid Mechanics May, 7-10 2003 Milano Marittima (Ravenna), Italy Archi.Me.Des. Dipartimento di Ingegneria Meccanica Università degli Studi di Brescia

2. 2nd Youth Symposium on Experimental Solid Mechanics 2 Rubber-to-metal devices Automotive applications: Vibrations-damping devices Vibrations- damping device for Mc-Pherson suspensions Engine mountings Adaptive journal boxes

3. 2nd Youth Symposium on Experimental Solid Mechanics 3 Materials Dynamic properties of elastomers Visco-elasticity Non - linearity Frequency dependence Temperature dependence Static pre-strain dependence HysteresisSelf-heating Stress Strain Temperature

4. 2nd Youth Symposium on Experimental Solid Mechanics 4 Experimental analysis Electro-dynamic shaker Fixtures Standard test-pieces Rubber-to-metal devices Material properties: Sweep of sine waves at constant deformation levels Shaker Vibrating board Test specimen Suspended mass Device global stiffness: K* E*G*

5. 2nd Youth Symposium on Experimental Solid Mechanics 5 Measurement chain Output AccelerationsSystem Frequency responseStiffness Shaker PC &Controller PowerAmplifier ADC Acceleration measurement Temperature measurement Drive signal Power drive Data Test Design DAC

6. 2nd Youth Symposium on Experimental Solid Mechanics 6 Stiffness measurement Suspended mass acceleration a OUT Imposed acceleration a IN Sine waves System global stiffness k System frequency response System global stiffness k( ) Youngs modulus E( )

7. 2nd Youth Symposium on Experimental Solid Mechanics 7 Deformation level increase causes: Results Effects of the deformation level decrease of E growth of E Pre-strain level increase causes: Effects of pre-strain, deformation and frequency G [MPa] growth of E

8. 2nd Youth Symposium on Experimental Solid Mechanics 8 Effects of temperature, frequency and deformation Results show good accordance with the master curves coming from DMTA

9. 2nd Youth Symposium on Experimental Solid Mechanics 9 Conclusions and discussions An innovative experimental approach based on the use of an electrodynamic shaker has been proposed to investigate the dynamic properties of viscoelastic systems and materials. Results obtained are in good accordance with theory and with those coming from traditional methods such as DMTA analysis. A method to estimate uncertainty related to stiffness measurements have to be defined.