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The selection of a rubber compound has a determining influence on the final characteristics of rubber-metal springs. Therefore, the correct selection of a rubber compound is a key factor for development of rubber-metal vibration isolation springs with required characteristics. The procedure for the selection of the rubber compound for vibration isolation of rubber-metal springs has been proposed, so that the rubber-metal elements have the necessary characteristics, especially in terms of deflection. The procedure is based on numerical simulation of spring deflection with Bergström-Boyce constitutive model in virtual experiment, with a goal to determine which parameters of the constitutive model will lead to spring required deflection. The procedure was verified by case study defined to select rubber compound for a rubber–metal spring used in railway engineering.

The temperature of rubber or rubber-metal springs increases under cyclic loading, due to hysteresis losses and low rubber thermal conductivity. Hysteresis losses correspond to energy dissipation from the rubber, which is primarily converted into heat. This well-known phenomenon, called heat build-up, is the primary reason for rubber aging. Increase in temperature within the rubber compound leads to degradation of its physical and chemical properties, increase in stiffness and loss of damping capability. This paper presents a novel procedure of heat generation prediction in rubber or rubber-metal springs. The procedure encompasses the prediction of hysteresis loss, i. e. dissipated energy within the rubber, by finite element analysis and application of a modern visco-plastic rubber constitutive model. The obtained dissipated energy was used as an input for transient thermal analysis. Verification of the proposed procedure was performed by comparison of simulation results with experimentally obtained data during the dynamic loading of the rubber specimen. The proposed procedure is highly computationally efficient and it enables time integration, which can be problematic in coupled mechanical thermal analysis. [Projekat Ministarstva nauke Republike Srbije, br. TR35005: Research and Development of New Generation of Wind Turbines of High Energy Efficiency]

The doctoral dissertation defines a new integrated methodology for the development of rubber-metal springs based on the application of modern virtual product development tools. The defined methodology encompasses all analytical, numerical, experimental and optimisation procedures necessary for the virtual rubber-metal springs development process. The main advantages of the new methodology reflect in the decrease in necessary experimental investigations, usage of realistic service loads instead of assumed loads and introduction of design of spring based on transmissibility and damping as the main parameters of the vibration control process. In contrast to the classical approach to rubber metal springs development, where the selection of rubber compound was done solely on previous experience of the designer, the thesis defines the systematic procedure for the selection of rubber compound based on the required spring natural frequency. Furthermore, the dissertation introduces a new procedure for approximate determination of the hysteresis damping value based on the experimental testing by uniaxial compression. The methodology also introduces a new procedure for the determination of heat generation during dynamic loading, as the main factor influencing rubber aging, which completely relies on virtual product development tools. The research into the prediction accuracy of several constitutive models of multiple rubber compounds commonly used in rubber metal springs was also conducted. In order to apply the finite element method in the rubber-metal springs development process, the new procedure for approximate determination of the rubber-metal contact friction coefficient value was developed and the research was conducted on the influence of finite element shape and order selection on the accuracy of rubber-metal springs numerical simulations using the finite element method. By applying the new methodology for the development of rubber-metal springs, the primary suspension spring of the locomotive 441 (444) of the JSC Serbian Railways was developed. The developed spring was manufactured, and laboratory and exploitation investigations were conducted, which led to obtaining the service permit for the railways operated by the JSC Serbian Railways. During the laboratory and exploitation testing the rubber-metal spring performed in accordance with the results obtained by the application of the new development methodology, which verified the new integrated development methodology and proved its practical applicability.

Rubber is a very flexible material with many desirable properties Which enable its broad use in engineering practice. Rubber or rubber-metal springs are widely used as anti-vibration or anti-shock components in technical systems. Rubber-metal springs are usually realized as a bonded assembly, however especially in shock absorbers, it is possible to realize free contacts between rubber and metal parts. In previous research it authors was observed that friction between rubber and metal in such case have a significant influence on the damping characteristics of shock absorber. This paper analyzes the development process of rubber or rubber-metal shock absorbers realized free contacts between the constitutive parts, starting from the design, construction, testing and operation, with special emphasis on the development of rubber-metal springs for the buffing and draw gear of railway vehicles.