Experimental and Numerical Sensitivity Assessment of Viscoelasticity for Polymer Composite Materials

Abstract

Viscoelastic polymer composites are widely used for vibration control in different fields of engineering like aerospace, mechanical, and structural engineering. The viscoelastic properties of these materials are strain rate-dependent and are highly related to frequency. Yet to date, less attention has been paid to quantifying the effects of these parameters and their interactions on damping properties and providing an approximation method for further applications. In the present research, a series of experimental tests was conducted on a viscoelastic material and the experimental data were numerically analyzed in detail. Sensitivity analyses are usually applied to quantify uncertainty using sampling techniques. However, in this study a method was proposed to derive a closed-form solution using the response surface function and a derivative-based global sensitivity analysis to evaluate the output contribution of each parameter. These effects were quantified and several approximation statistics were provided for future engineering implementations. The computational evaluation conducted in this study gives a detailed insight into the mechanical behavior of viscoelastic materials.Viscoelastic polymer composite materials or, in short here, viscoelastic materials (VEMs) are effectively used to attenuate the dynamic response of various devices and structures and dissipate the acoustic energy due to their viscoelasticity and damping properties 1-7 . Having a quite accurate estimation of these properties and their mechanical behavior is of paramount importance in engineering design. However, the key point about the application of VEMs is their complex behavior due to the strain-rate dependency which can be also unknown prior to the design. Hence, there is a need to quantify these effects and provide a confidence interval for practical implementation of these materials. The main factors affecting the mechanical behavior of VEMs are excitation frequency, strain amplitude, number of cycles, and ambient temperature. The storage modulus of reinforced vulcanized elastomers decreases as a function of strain amplitude, and the loss modulus shows an initial increase but decreases afterwards, which is called the Payne effect 8,9 . Many experimental studies have been carried out to evaluate the effects of these factors 10-14 and they showed that the damping properties of VEMs are more or less sensitive to these factors. Chang et al. 14 stated that the load frequency and the temperature have significant effects on dynamic characteristics. However, no significant effects were observed for strain amplitudes limited to 0.5 in their designed experiment. Therefore, the effects of strain amplitude was not considered in derivation of empirical functions 14 . Eftekhari and Fatemi 15 studied the influence of loading frequency on the fatigue behavior of several composites under constant amplitude fatigue test. They developed an analytical model to take into account the effects of frequency, stress, temperature, and fiber orientation on the fat...

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Inverse Modeling of Viscoelasticity Materials using Physics Constrained Learning

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