An introduction to heat transfer

Fatigue failure analysis of anti-vibration rubber spring

Polyvinyl pyrrolidone (PVP) modified reduced graphene oxide (PRGO) was prepared through chemical reduction of graphene oxide (GO) in the presence of PVP. The PRGO/natural rubber (NR) nanocomposites were fabricated by mixing PRGO aqueous dispersion with NR latex, followed by coagulation and vulcanization. The structure of PRGO was characterized using UV–vis absorption spectroscopy, Atomic force microscope, Solid state 13 C NMR and X-ray photoelectron spectroscopy. The thermal conductivity, swelling and mechanical properties of PRGO/NR nanocomposites were also investigated. The results showed that GO was reduced effectively in the presence of PVP, and the PVP molecules were absorbed on the basal plane of reduced graphene oxide (RGO) through non-covalent interactions. With the increase of PRGO, thermal conductivity and storage modulus of PRGO/NR nanocomposites increased, whereas solvent uptake decreased. Compared with unfilled NR, NR with 5 phr (parts per hundred rubber) PRGO had a 30% increase in thermal conductivity and 37% decrease in solvent uptake. Under the condition of adding 3 phr PRGO, the tensile and tear strength of NR nanocomposite were improved by 23% and 150%, respectively.

Multifunctional nanocomposites between natural rubber and polyvinyl pyrrolidone modified graphene

The dynamic fatigue life of rubber

The stress-endurance (S-N) method has been widely used in metal fatigue in the railway industry over many years. However, when this method is applied to rubber-like materials, it seems not as successful as when it is applied to metallic materials. Recently, an integrated fatigue evaluation programme has been carried out with the aim of improving the design of antivibration components in response to the increasing demands of the rail operating environment. This programme will also make simulations more reliable and relevant to industrial applications, especially for the fatigue design of rubber springs used in rail vehicle suspensions. The continuum mechanics (total life) approach has been used to characterize the fatigue life in terms of the cyclic stress range (S-N curve). It is suggested that the effective stress, sigma(f), can be used as a parameter (taking three principal stress ranges into consideration) to evaluate fatigue failure. The initial verification of this approach has been carried out on two types of rubber spring. The results have shown good agreement between the fatigue test of the components and the simulation based on this approach.

An approach to evaluate the service life of rubber springs used in rail vehicle suspensions

Fatigue failure investigation on anti-vibration springs

Rubber-to-metal bonded springs are vital antivibration components for rail vehicles. Metacone rubber springs are widely used as a primary spring on a rail vehicle fitted at the wheel axle b...

Fatigue design of rubber springs used in rail vehicle suspensions

This paper reports on an integrated real-time simulation and experimental program that was carried out on a rubber spring anti-vibration part used as a rail vehicle component. This work was designed to ensure that any temperature rise inside an anti-vibration part does not exceed the design requirement in accelerated fatigue tests. Results from both testing and simulation indicate that the energy loss per cycle of the rubber spring, under fixed dynamic amplitude, does not depend on the loading frequency. Therefore, the energy loss per cycle can be more easily obtained using a conventional quasi-static loading procedure than from conducting more complicated dynamic tests. The method presented here is shown to be reliable for evaluating the temperature effects caused by dynamic loading. A detailed thermal stress analysis can also be carried out by feeding back the thermal effects. Key rubber parameters obtained from the authors' material testing laboratory are presented here as references for similar applications in railroad industries.

WJ Mortel

Papers

An approach to evaluate the service life of rubber springs used in rail vehicle suspensions

Fatigue failure investigation on anti-vibration springs

Fatigue design of rubber springs used in rail vehicle suspensions

A method to predict the heat generation in a rubber spring used in the railway industry

Rubber-unloading-behaviour evaluation using product-orientated specimen based on a resilience test