Trelleborg IAVS

Leicester, United Kingdom

Trelleborg IAVS

Leicester, United Kingdom
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Luo R.K.,Trelleborg IAVS | Mortel W.J.,Trelleborg IAVS | Cook P.W.,Trelleborg IAVS | Lake J.,Trelleborg IAVS
Plastics, Rubber and Composites | Year: 2011

The offset sandwich mount design is often considered for application on rail vehicles. This paper reviews several different aspects of the product. These include the more commonly evaluated benefits of higher order material properties, the product design and its associated geometry optimisation. It is shown that a large error occurs when calculating the rubber shrinkage using a constant coefficient in the moulding process. Hence a postulation is made to link the compressibility with temperature change, which leads to the accuracy increased by fivefold against the measurement. A design concept, balancing the internal moments in different layers of the component, is proposed for this type of the product. Finally the paper suggests an effective stress criterion which takes into account all stress components when considering the complications associated with multiaxial loadings. The objective is to identify which can be considered the best approach for crack initiation evaluation. © Institute of Materials, Minerals and Mining 2011.

Luo R.K.,Trelleborg IAVS
International Journal of Damage Mechanics | Year: 2014

In industry, the important design parameters of rubber products are currently based on only the loading part of loading-unloading histories, e.g. load-deflection and the fatigue requirement. Rubber-like materials exhibit an appreciable change in their mechanical properties during the loading-unloading process, especially in the first few cycles from a virgin state. There is neither a universally well-defined approach to evaluate the Mullins damage effect on design aspects in industry, nor a reliable criterion to evaluate it for rubber products. An approach based on rebound energy (resilience) change is proposed to predict the Mullins damage effect with residual strain. A rubber product, manufactured in industry, was selected for experiment and verification. A Mullins indicator, in term of the maximum loading forces over the accumulated residual deflections over the loading-unloading cycles, is proposed for a criterion to evaluate the Mullins damage effect. It is indicated that the first loading-unloading cycle removes the Mullins effect by approximately 80% and a typical three loading-unloading cycles in industrial practice can remove Mullins effect by approximately 94%. More than three loading-unloading cycles are suggested to reach a state for achieving the required accuracy on smaller tolerance of design parameters. The proposed approach provides the reliable prediction on the first loading-unloading and subsequent reloading-unloading cycles, and can be used for engineering design and industrial applications. Nevertheless, the proposed approach should be further verified using more industrial cases. © The Author(s) 2014.

Mortel W.J.,Trelleborg IAVS
Constitutive Models for Rubber VIII - Proceedings of the 8th European Conference on Constitutive Models for Rubbers, ECCMR 2013 | Year: 2013

In an ideal world the Customer issues a product specification which can then be designed and manufactured. Validation of the design probably includes use of various forms of numerical analysis by both the customer and the supplier. This paper considers the complexity of harmonising the goals between the Customer-with his specification variables, the Designer-with his product design variables, and the Manufacturer-with his process variables. Case studies are considered, where Finite Element Analysis has been used as the validation tool with different aspects of complexity. Not least the choice of constitutive model which provides the correct evaluation. With everyone within the supply chain theoretically having the same objectives, the presentation attempts to illustrate the interactions which can have different benefits, and understanding, of the product performance by those parties. © 2013 Taylor & Francis Group.

Luo R.K.,Trelleborg IAVS | Lake J.,Trelleborg IAVS | Mortel W.J.,Trelleborg IAVS
Constitutive Models for Rubber VIII - Proceedings of the 8th European Conference on Constitutive Models for Rubbers, ECCMR 2013 | Year: 2013

Rubber is a high non-linear elastic material. Rubber springs are widely used in industry as anti-vibration components. This type of anti-vibration unit is designed to have much more wider applications under different loading modes, compared with standard components. The key requirement for this design is that the unit can be easily assembled. Then load deflection can be assessed in vertical, lateral and longitudinal directions. However, the assembly stage was not completed due to large dimension difference between the moving core and the outer metal case. Hence a pre-compression load has to be introduced for the possibility of assembly completion. It was found that that the more pre-compression load applied the more progress made. On the other hand the pre-compression load was causing severe distortion of the rubber section which prevented the simulation finishing. Many iteration steps were made to achieve 100% assembly stage. The prototype of the design is finally approved and ready for production. This technical note reports the simulation process of the assembly in detail. Finally the CPU usage is discussed and equations between the wall clock time and CPU numbers are obtained. Suggestions are made to balance the cost and the efficiency. It can be used as a guide for the effective CPU usage for smaller companies. © 2013 Taylor & Francis Group.

Luo R.K.,Trelleborg IAVS
Polymer Testing | Year: 2016

There is very limited literature regarding impact analysis on solid rubber anti-vibration systems as the true damping characteristics of rubber materials are very complex and difficult to define. Viscoelastic approach is a usual method and has only achieved limited success. In this article, an integrated quasi-static and impact analysis with validation on an anti-vibration mount is presented. The Rayleigh damping has been introduced for rubber hysteresis. The impact responses from both simulation and experiment have been compared and have shown very good agreement in real time domain. In addition, it has been revealed that real geometry and elasticity of an impact object have to be included in simulation in order to obtain an accurate response. It has been shown that the proposed approach is reliable and can be used for an appropriate design stage to evaluate an impact/dynamic response of rubber anti-vibration systems. The key points to use this approach are also provided. © 2016 Elsevier Ltd. All rights reserved.

Luo R.K.,Trelleborg IAVS | Mortel W.J.,Trelleborg IAVS | Sewell S.,Trelleborg IAVS | Moore D.,Trelleborg IAVS | Lake J.,Trelleborg IAVS
Constitutive Models for Rubber VII - Proceedings of the 7th European Conference on Constitutive Models for Rubber, ECCMR | Year: 2012

There is very little literature regarding rubber dynamic simulations. In many engineering applications the dynamic analysis is normally not required. However there is more demanding requirement for quantitative specification of dynamic behaviour of rubber-to-metal bonded anti-vibration components. This case study is based on an engine installation where there is a need for understanding of the products complex stiffness and damping. Initially the model has been verified by quasi-static tests, followed by a dynamic test programme within a test laboratory. A three-dimensional finite element model has been developed to predict the natural frequencies and mode shapes for the product. At same time a steady state dynamic response from a damped harmonic input is also evaluated. Compared with the test result, it is concluded that the simulation is reliable and can be used in the proper design stage when dynamic characteristics are needed. © 2012 Taylor & Francis Group.

Luo R.K.,Central South University | Peng L.M.,Central South University | Wu X.P.,Central South University | Mortel W.J.,Trelleborg IAVS
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit | Year: 2012

Rubber suspensions are important components in railway vehicles. The offset sandwich mount is a type of rubber spring used on rail vehicles as the primary suspension above the axlebox on a bogie. In this installation, a pair of mounts is arranged within a vee configuration, such that the movements in all planes are controlled by a combined shear and compression displacement. This article evaluates the important aspects in the rubber suspension design when using a higher order material properties in an extreme large deformation. On one hand, using a higher order of material model has enabled prediction of larger deformations that are required for the actual product in the ultimate loading used in rail dynamic environment. On the other hand, using a higher order of material model with full integration elements, however, may mislead the design concept to an incorrect direction. It is important to note that the accuracy of the stress calculation is not guaranteed by a reasonable load-deflection prediction, even validated against a test result. Three methods to check the reliability of the calculated stresses are proposed. The investigation has been validated against a laboratory test. It is suggested that a higher order of material model should be used with reduced integration elements. © Authors 2011.

Luo R.K.,Central South University | Mortel W.J.,Trelleborg IAVS | Wu X.,Central South University | Peng L.M.,Central South University
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit | Year: 2016

In the rail industry, the important design parameters of rubber suspension systems are currently solely based on the loading part of the loading/unloading history, e.g. the load-deflection characteristics and fatigue requirement. Different energy levels and stress values are created for an identical load value during loading and unloading cycles in rubber-like materials. Hence, the performance of a rubber suspension can be substantially different during loading and unloading, which can lead to unexpected effects. An engineering approach is proposed to account for this so-called Mullins effect. Existing elastomeric models, widely used in rail vehicle design, can be modified to account for the unloading using this methodology. A typical rubber-to-metal bonded component, which is used in rail suspension systems, is selected for a verification study. It is shown that the predictions from the new approach are consistent with the results of the whole load/deflection history obtained in a laboratory experiment. In addition, if the unloading characteristics are not considered, results obtained from stress calculations can have a 20% margin of error. The proposed approach should be further verified using other types of rubber suspension systems. © 2014 Institution of Mechanical Engineers.

Luo R.K.,Trelleborg IAVS | Wu X.,Central South University | Mortel W.J.,Trelleborg IAVS
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit | Year: 2013

Rail vehicles operate in highly complex dynamic environments. Rubber-to-metal bonded springs are used as both primary and secondary suspensions as well as engine installations in order to minimize vibration levels. The effect of rubber hysteresis is usually studied using viscoelastic models; however, this paper proposes an approach in which Rayleigh damping coefficients are introduced to model the rubber hysteresis. Simulations of the dynamic response of a rectangular rubber spring are performed and it is found that the natural frequencies of the rubber suspensions and engine installations on a railway vehicle show little change under both the tare and loaded conditions in service. The steady state dynamic response to a harmonic input in the frequency range between 1 and 1000 Hz is calculated and subsequently validated against experimental results. In addition the effect of a sudden impact, created by track irregularities, on the rubber suspension and engine installation is analysed. The proposed methodology may be used to guide the design of the rubber structures used in railway vehicles. © IMechE 2012.

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