Speaker
Description
The research is devoted to the rheological properties of viscoelastic materials, which are used to reduce excessive vibrations in passive damping systems in high buildings loaded with wind or in buildings located in seismic areas. It is extremely important but also difficult to correctly describe the dynamic behavior of a viscoelastic material, since its rheological characteristics depend on the ambient temperature, on the frequency of the forcing load and on the amplitude of vibration. There are many papers in the literature devoted to the study of advanced rheological models that are trying to consider all these factors.
The behavior of viscoelastic material over a wide range of temperatures and frequencies is well described by rheological models using non-integer order derivatives, e.g., the four-parameter fractional Zener model [1]. In this work, a five-parameter model is proposed, which was obtained after extending the aforementioned Zener model and which takes into account the effect of vibration amplitude on the dynamic behavior of the viscoelastic material. The extension consisted in adding a nonlinearity in the part describing elasticity, so the new model can be called: nonlinear fractional Zener model.
The use of the five-parameter model involves significant difficulties when trying to describe the actual rheological material, since it is necessary to identify these parameters, for example, from laboratory test results [2]. To overcome these difficulties, the harmonic balance method [3] was used and a complex version of this method was chosen.
The effectiveness of the method was tested on an artificially generated experimental data set. The method was then used to identify model parameters to properly describe the selected viscoelastic material designated for vibration reduction in structural systems, depending on the frequency and amplitude of vibration.
[1] Pawlak, Z.M.; Denisiewicz, A. Identification of the fractional Zener model parameters for a viscoelastic material over a wide range of frequencies and temperatures. Materials (2021), 14, 7024. https://doi.org/10.3390/ma14227024
[2] Javidan, M.M., Kim, J. Experimental and Numerical Sensitivity Assessment of Viscoelasticity for Polymer Composite Materials. Scientific Reports, (2020), 10, 675.
https://doi.org/10.1038/s41598-020-57552-3
[3] Lewandowski, R. Nonlinear steady state vibrations of beams made of the fractional Zener material using an exponential version of the harmonic balance method. Meccanica (2022), 57, 2337–2354. https://doi.org/10.1007/s11012-022-01576-8
