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Li X.,Tsinghua University | Li X.,CRRC Qingdao Sifang Rolling Stock Research Institute Co. | Wei Y.,Tsinghua University | Feng Q.,Tsinghua University | Luo R.K.,Trelleborg Industrial Anti Vibration Systems
Fibers and Polymers | Year: 2017

Many industrial products are made of cord-rubber composite materials. Their mechanical behavior not only depends on rubber but also depends on cord. Nylon 66 cord is one of the most important reinforcement in these products. This paper research the mechanical behavior of nylon 66 cord under various load cases. A series of experiments were carried out to obtaining stress-strain curves under different load cases. Complex changes of the modulus and Mullins effect can be found in monotonic and cyclic tension, respectively. Mechanism of these behaviors has been analyzed considering both the twisted structure and material. A phenomenological constitutive model, accounting for different loading conditions, has been firstly proposed base on strain energy density function and damage mechanics method. The proposed model has been verified by comparing the predicted results with experimental data. It has been found that the proposed model predicted the stress-strain curves that were consistent with the experimental data. The proposed model can be implemented in finite element software for engineering design and application. © 2017, The Korean Fiber Society and Springer Science+Business Media Dordrecht.

Luo R.K.,Central South University | Peng L.M.,Central South University | Wu X.,Central South University | Wu X.,University of London | Mortel W.J.,Trelleborg Industrial Anti Vibration Systems
Polymer Testing | Year: 2014

An approach based on rebound energy (resilience) change is proposed to predict stabilisation of the Mullins effect for anti-vibration systems. A silicone rubber product manufactured in industry was selected for experimentation and verification. A Mullins indicator, in terms of the maximum loading forces over the accumulated residual deflection throughout the loading-unloading cycles, is proposed as a criterion to evaluate the stabilisation of the Mullins effect. Industry typically employs a three-loading/unloading-cycle routine on this silicone rubber product to remove the Mullins effect by approximately 75%. To achieve 95% accuracy for stabilisation, seven loading-unloading cycles are suggested. Verification shows that the proposed approach predicts results very close to measured experimental values, and the method can be used for engineering design and industrial applications. © 2014 Elsevier Ltd. All rights reserved.

Luo R.K.,Central South University | Wu X.P.,Central South University | Mortel W.J.,Trelleborg Industrial Anti Vibration Systems
Polymer Testing | Year: 2014

In industry, the important design parameters for rubber products are currently almost always based on only the loading part of loading-unloading histories, i.e., load-deflection and fatigue requirements. Rubber-like materials experience different strain energy levels and stress values during loading and unloading for the same load value. Hence, the performance of rubber products may be substantially different during loading and unloading, which can lead to unexpected effects, including the Mullins effect. Herein, a new approach is proposed to account for the Mullins effect. Existing elastomeric models, which are based on the strain energy density, are modified during loading and unloading. A key engineering parameter, the rebound resilience (the ratio between the rebound energy and the initial loading energy), is introduced in this approach. A typical rubber-to-metal bonded component, which is widely used in engine installation, is selected to validate the proposed approach. It has been shown that the predictions offered by the new approach are consistent with the load-deflection histories yielded by loading-unloading experiments. In addition, if the unloading characteristics are not considered, the results obtained from the stress calculations can show an error margin 30%. © 2014 Elsevier Ltd. All rights reserved.

Luo R.K.,Central South University | Mortel W.J.,Trelleborg Industrial Anti Vibration Systems | Wu X.P.,Central South University
Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications | Year: 2015

Heat generation due to dynamic loading has been a major concern for rubber component manufacturers over many years. In engineering design and applications, current practice is to monitor the component surface temperature in accelerated durability tests. However, a number of unexpected early failures from heat generation during accelerated durability tests for rubber components have been observed even the surface temperature was well-controlled. This situation has led to the development of heat generation prediction methodology. An integrated simulation and test programme has been set up on a case investigation on a solid rubber wheel. A drum test was carried out in the laboratory. Heat conductivity, convection and radiation are included in the simulation. Important rubber heat-Transfer properties were measured in the laboratory and used for the simulation. A mixed Lagrangian/Eulerian method was successfully introduced in the simulation, due to the limitations of traditional FE methods, to reduce a great amount of cost and to make the simulation possible in practice. In this case, the degrees of freedom can be reduced by three times and about 170,000 rotations saved. The temperature change in real time-domain was recorded and failure regions located. The simulation results have shown that the temperature difference between the surface and inside in the solid rubber wheel can go about four-folds. The results have been compared with the laboratory test and shown very good agreement. From this investigation, it is shown that a proper calculation is needed when a product involves a large volume of the rubber during dynamic-loading tests, and the criterion to monitor the surface temperature alone is not always reliable and could lead to a potential unexpected failure. The principles and techniques can be employed for the prediction on heat generation in industries. © 2013 IMechE.

Luo R.K.,Trelleborg Industrial Anti Vibration Systems | Luo R.K.,Central South University | Wu X.,Central South University | Wu X.,University College London | Peng L.,Central South University
Polymer Testing | Year: 2015

This article presents engineering approaches to evaluate creep loading response and a complete loading-unloading procedure for rubber components used as anti-vibration applications. A damage function for creep loading and a rebound resilience function for mechanical unloading are introduced into hyperelastic models independently. Hence, a hyperelastic model can be extended for both creep and unloading evaluations. A typical rubber product and a dumbbell specimen were selected to validate the proposed approaches. It has been demonstrated that the predictions offered by the new models are consistent with the experimental data. In addition, a loading procedure using the same final value, with and without involving unloading, prior to a creep test can produce different results. The proposed approach can capture this phenomenon which was observed in the literature. The proposed approach can also be easily incorporated into commercial finite element software (e.g., Abaqus). It is demonstrated that the proposed method may be used for anti-vibration products at an appropriate design stage. © 2015 Elsevier Ltd. All rights reserved.

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