The paper focuses on a nonlinear model to represent the mechanical behaviour of a mix coil spring – rubber used in the secondary suspension of passenger rail vehicles. The principle of the model relies on overlapping of the forces corresponding to three components – the elastic component, the viscous component and the dry friction component. The model has two sources on non-linearity, in the elastic force and the friction force, respectively. The main attributes of the model are made visible by its response to an imposed displacement-type harmonic excitation. The results thus obtained from the applications of numerical simulation show a series of basic properties of the model, namely the dependence on amplitude and the excitation frequency of the model response, as well as of its stiffness and damping.
There is general agreement that primary pyrolysis products of end-of-life tyres should be valorised to improve the economics of pyrolysis. In this work, tyre pyrolysis char (TPC) is produced in a pyrolysis pilot plant designed and built at our home university. The produced TPC was upgraded to tyre-derived activated carbon (TDAC) by activation with CO2, and then characterised using stereological analysis (SA) and nitrogen adsorption at 77 K. SA showed that the grains of TPC and TDAC were quasi- spherical and slightly elongated with a 25% increase in the mean particle cross-section surface area for TDAC. The textural properties of TDAC demonstrated the BET and micropore surface areas of 259 and 70 m2/g, respectively. Micropore volume and micropore surface area were 5.8 and 6.7 times higher for TDAC than TPC at 2 nm, respectively. The n-hexane adsorption was investigated using experiments and modelling. Eight adsorption isotherms along with three error functions were tested to model the adsorption equilibrium. The optimum sets of isotherm parameters were chosen by comparing sum of the normalized errors. The analysis indicated that the Freundlich isotherm gave the best agreement with the equilibrium experiments. In relation to different activated carbons, the adsorption capacity of TDAC for n-hexane is about 16.2 times higher than that of the worst reference material and 4.3 times lower than that of the best reference material. In addition, stereological analysis showed that activation with CO2 did not change the grain’s shape factors. However, a 25% increase in the mean particle cross-section surface area for TDAC was observed.
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