Cord-rubber Composites Research Articles

Smart cord-rubber composites with integrated sensing capabilities by localised carbon nanotubes using a simple swelling and infusion method

Smart self-sensing composites with integrated damage detection capabilities are of particular interests in various applications ranging from aerospace and automotive structural components, to wearable electronics and healthcare devices. Here, we report a straigthforward methodology to introduce and localise conductive nanofillers into existing elastomeric coatings of reinforcing cords for interfacial damage detection in cord-rubber composites. A simple swelling and infusion method was developed to incorporate carbon nanotubes (CNTs) into the elastomeric adhesive coating of glass cords. Conductive CNT-infused glass cords with good self-sensing functions were achieved without affecting the bonding provided by the coating with the rubber matrix. The effectiveness of using these smart cords as interfacial strain and damage sensors in cord-rubber composites was established under static and cyclic loading and demonstrated its potential in identifying both reversible deformation and irreversible interfacial damage. The simplicity of the proposed swelling and infusion methodology provides great promise for large-scale industrial implementation or the modification of existing elastomeric products.

Static stiffness characteristics of a new non-pneumatic tire with different hinge structure and distribution

To eliminate the potential risk factors of the conventional inflatable tire, a creative non-pneumatic tire named “ME-wheel” was developed. Based on the analysis of the bearing characteristics, four types of ME-wheel with varying hinge structures and distributions were designed. The static stiffness characteristics of these four ME-wheels were investigated by numerical simulations and experiments. The hyperelasticity and incompressibility of the rubber material were described by the Mooney–Rivlin model, and the multilayer rubber-cord composites were modeled by the rebar layer. The nonlinear finite element model of the ME-wheel, which included nonlinear property of the material, contact condition, and anisotropy of rubber-cord composites, was validated by the load characteristic test. Stiffness characteristic tests of these four types of ME-wheel and a pneumatic tire, including vertical, longitudinal, lateral, and torsional stiffness, were carried out using a low speed flatbed test bench. A sufficient comparison and analysis were made between the experimental data and simulation data. The research results provided some theoretical and technical verification on the performance and structural optimization of the ME-wheel.

The Effect of Molecular Complexes of Lactam-Containing and Proton-Donor Substances on the Adhesion Properties of Adhesive Composites

The results of investigating the effect of a molecular complex (MC) based on a lactam-containing product and a hydroxyl-containing compound on the adhesion properties of elastomeric adhesives are set out. The MCs comprise binary melts based on triatomic alcohol (TA) and ε-caprolactam. An MC was introduced into an adhesive based on chloroprene rubber in different ratios together with the isocyanate 4,4’-methylenediphenyl diisocyanate (MDI). The adhesion activity of the MC was assessed from the bond strength between the elements in rubber–cord composites (a rubber compound based on BNKS-40AMN nitrile butadiene rubber + cord coated with a rubber mix based on general-purpose rubbers according to GOST 6768-75). Comparison of the IR spectra (FSM 1201 IR Fourier spectrometer) of the MC and its individual constituents makes it possible to suggest the presence of hydrogen bonds in the MC. Analysis of NMR spectra (Bruker Avance-400 NMR spectrometer) of the MC showed the absence of new chemical bonds between its components. Theoretically, a binary MC introduced into an adhesive composite together with isocyanate should promote an increase in the bond strength between the substrates through the formation of urethane groups. The results of testing the MC in the composition of adhesives showed that a higher bond strength is possessed by rubber–cord specimens with a ratio of TA and ε-caprolactam of 2:1. The introduction of an MC together with MDI leads to a 25% increase in adhesion strength in the adhesive joint.

An investigation of intelligent tires using multiscale modeling of cord-rubber composites

ABSTRACTA computational model based on the multiscale progressive failure analysis is employed to provide the theoretical predictions for damage development in the cord-rubber composites in tires. Vulcanized rubber, reinforcing belts, and carcass used in tire structures cause the anisotropic behavior under different loading conditions. Steel reinforcement layers made of steel wires combined with rubber complicate the macro-scale finite element modeling of tires. This paper presents a new three-dimensional model of the cord-rubber composite used in tires in order to predict the different types of damage including matrix cracking, delamination, and fiber failure based on the micro-scale analysis. Additionally, intelligent tires have the potential to be widely used to enhance the safety of road transportation systems, and this paper provides an estimation of the effects of void volume fraction, fiber volume fraction, and stacking sequence of the cord-rubber composites on the acceleration profile of the tire measured at the inner-liner.

Numerical and experimental investigation on the camber performance of a non-pneumatic mechanical elastic wheel

Tire safety is a pretty important performance for the vehicle. To overcome some disadvantages of the conventional pneumatic tire, a new non-pneumatic mechanical elastic wheel (ME-Wheel) is developed, and the camber performance of ME-Wheel is studied with numerical and experimental methods. A nonlinear three-dimensional finite element model of the ME-Wheel, which includes material nonlinearities, large deformation and the anisotropy of rubber–cord composites, is established. The rubber components of the ME-Wheel are analyzed by Moony–Rivlin model. With a vertical test rig, static loading tests are performed to validate the accuracy and reliability of the finite element model. Experiments and simulations under the static and rolling conditions are conducted to study the influence of different camber angles on the vertical stiffness, wheel deformation, contact pressure distribution and wheel force at the interface. The simulation results and the test results are compared and discussed in detail. The results show that the proposed method is useful for the investigation of mechanical characteristics of ME-Wheel and the later optimal design.

Experimental observations of orthotropic elastic and viscoelastic characteristics of the elastomeric textile reinforced composites

The paper deals with investigation elastic and viscoelastic properties of elastomeric composites by experimental tests. The composites has a textile unidirectional reinforcement. A displacement control load has been posed i.e. fixed values of strains has been set for specimen. Thus, an occurring effort has been measured. Quasi-static loading was applied to specimen. The results are automatically recorded, for each test in real time that gives a possibility to obtain detailed deformation curves of the material. Tests have been carried out in three principal directions: tensile test along reinforcement textile cord, tensile test across the reinforcement, and the test on compression of a plate in the direction perpendicular to the plane of the composite reinforcement.The experiments have been carried out under a cyclic loading with different amplitudes. The experiments have been conducted with strain sweep 2% and 5%. Engineering evaluation for the average initial modulus for this material has been also defined in each principal direction of the composite. The available experimental data allows to determine the area of the hysteresis loop by numerical integration for cycles. These results allows to estimate the viscous component of the deformation of rubber-cord composite. Appropriate experimental observations have been carried out with different amplitudes of loading in different directions. Thus, a loss modulus is evaluated depending on strain amplitude in different loading directions

Fatigue mechanisms of cord–rubber composites

AbstractThis article presents a continuum damage mechanics approach to characterize fatigue mechanisms of cord‐rubber composites. An airspring bellow which consists of layers of rubber and reinforcing cords is considered for this work. The phenomenological material model for rubber is formulated for the purpose of analyzing the rate dependent behavior under cyclic loading. The rate dependency and hysteretic behavior are characterized by using the concept of internal variables [1]. The implementation of the constitutive formulation for rubber material is done in ABAQUS via UMAT.A fatigue failure mechanisms of cord‐reinforced airspring is for example interfacial debonding. Within the framework of finite element cohesive zone modeling, a user element is developed to study the cord‐rubber interfacial debonding. Furthermore, the developed methodology can be easily extended to understand the long‐term effects of e.g. temperature, frequency, loading rates, amplitudes etc. on the fatigue life of airsprings. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Numerical analysis of effective mechanical properties of rubber-cord composites under finite strains

In this article, a method and an algorithm are developed by which the effective mechanical properties of rubber-cord composites are numerically estimated, with the finite strains and low compressibility of rubber accounted for. The effective properties are derived in the form of a quadratic relation between the Green deformation tensor and the second Piola–Kirchhoff stress tensor. Numerical results obtained using implementation of this algorithm show good agreement with analytical formulas. The results of the numerical estimation of the effective mechanical properties of rubber-cord composite under finite strains are given in the article. The numerical analysis is carried out using the finite element method. Dependences of the effective modules on the elastic properties of cord and rubber and on the cord pitch are investigated for single-layer rubber-cord. Dependences of the effective modules on the cord angle are investigated for two-layer rubber-cord. Graphs of these dependences are given in the article.

Flat Shell Stress-strain State Calculation

The numerical study using finite element method of flat shell H-327stress-strain state was carried out in this paper. The possibility of reinforced flat shells modeling with overlapping cord threads with plane finite elements was presented. The shell elements calculation was carried out to obtain data on equivalent elastic properties of the rubber-cord composite.

Assessing micromechanical behaviour of PET cords in rubber matrix composites by laser Raman microscopy

Abstract The mechanical behaviour of PET cord-rubber composites has been investigated by adopting a multi-scale approach by combining standard tensile testing and laser Raman microscopy (LRM). Tensile tests were performed on cord-rubber composite and on its constituents to gain information on the mechanical response at the macro-scale. The behaviour at smaller scales was assessed by means of LRM, which has already been established as a technique that can yield values of stress or strain of reinforcement at the micro-scale. The effects of cord content, composite configuration and sample length have been examined. In particular, the efficiency of stress/strain transfer to the embedded cord has been evaluated and correlated to the micromechanical behaviour through the ‘finite fibre length effect’ observed at the macro-scale.

Effect of Cord Construction on the Properties of Rubber Composites

Cord-rubber composites are different from the general rigid-matrix composites because of the twisted nature of cords and the large, nonlinear deformation of rubber material. The study of the effect of cord construction on their mechanical properties is essential to the improvement of the performance characteristics of rubber products. However, little work was concerned with the influence of the number of strands of cord. The present work demonstrated that influence by using nonlinear finite element analyses. The calculated results show that the effective moduli of the twisted cord reinforced composites tend to be closer to that of a single strand of cord reinforced composites when increasing the number of strands with a constant cord volume fraction. For three types of reinforcing cords, the shear stresses have a symmetric distribution and an anti-symmetric distribution in the condition of in-plane shearing and axial loading, respectively. It is also found that the minimum MISS (maximum interfacial shear stress) occurs in the case of a single strand of cord in comparison with the cases of the twisted cords, and the maximum MISS is related to the loading conditions and the number of strands.

An anisotropic hyperelastic constitutive model with shear interaction for cord–rubber composites

Abstract An anisotropic hyperelastic constitutive model for tire cord/rubber composites is proposed. The strain energy of the cord/rubber composites material is nominally decomposed into four parts, representing the strain energy from rubber, cords, shear interaction and normal interaction between rubber and cords, respectively, which makes a separate investigation of contribution of each part of strain energy available. The geometric relationship between the cord and rubber, in the original and current configuration, is analyzed in determining the characteristics of each strain energy part. By including the so called shear interaction and normal interaction strain energy which cannot be neglected under particular deformation conditions, the accuracy of the model is greatly improved. A simple approach for fitting the model parameters is given. Experimental data from literature is used to identify these material parameters in the constitutive model for a specific cord/rubber composite. The developed constitutive model is validated through a comparison between experimental data and predicted results under certain deformation modes. Very good agreement is obtained.

Experimental investigation on high strain rate tensile behaviors of steel cord–rubber composite

High strain rate tensile tests of steel cord–rubber composite with different cord orientations have been performed on a servo-hydraulic testing machine. Two types of steel cord arrangement reinforcing to the same rubber material have been studied. Material properties and damage behaviors were identified. Damage mechanisms were studied for range of the strain rates going from 3.3×10−3 to 131s−1. The effect of strain rate revealed tendencies of tensile fracture properties on the steel cord–rubber composites. The onset and the propagation of damage such as interfacial debonding were observed using high speed camera in order to understand damage mechanisms. The failure modes were found to be dependent on the cord orientations inducing particularly tensile fracture properties.

Mechanical Properties of Aged Cord-Rubber Composites

Cord-rubber composites are usually subjected to cyclic deformation for the tire applications. Due to the hysteretic nature of the rubber, heat generation in the rubber component under dynamic cyclic loading often causes a rise in temperature, which can deteriorate the physical properties of the composites. Therefore, better understanding of the cord-rubber composites under thermal aging conditions is of great importance for the lifetime prediction. In the present work, the effective modulus of polyester cord- and steel cord-rubber composites at different aging conditions was studied by means of the mechanics of composite materials and the Arrhenius relationship based on the properties of components. It is found that the Halpin-Tsai relation with introducing the effect of thermal aging is also valid for the aged cord-rubber composites.

Study on Deflection Performance of Radial Tire by Finite Element Method

In order to improve vehicle safety, the accurate determination of the tire's loading behaviour is necessary in the domain of vehicle dynamics. The interaction between the tire and the surface of the road must be understood thoroughly. A 3D finite element model of the tire-road has been built by using MARC software according to the actual construction of the 195/60R14 radial tire. The rebar model of the radial tire is employed to simulate the complex multilayer cord-rubber composites and directly define the cord directions varying with their positions. The geometric nonlinearity due to large deformation, material nonlinearity and the nonlinear boundary conditions from tire–rim contact and tire–road contact are also considered. The relationships between load and the tire deflection, the tire deformation, the contact stress distribution and the distribution of the contact friction force are discussed.

Investigation of the vibration characteristics of radial tires using experimental and numerical techniques

A 3D finite element model of modal analysis has been established based on MSC.MARC software according to the practical structure of 195/60R14 radial tire. The rebar model is employed to simulate complex multilayer rubber-cord composites. The model considers the geometric non-linearity and the non-linear boundary conditions from tire-rim contact and tire-road contact. The modal test systems are developed for the free suspension tire and the grounding tire. The vibration characteristics of the radial tire are studied numerically and experimentally. Mode shapes (lobes) of the radial vibration are in a strong regularity with the change of the mode order. The first mode shape has two lobes, the second mode shape has three lobes, and so on. Changes of the inflation pressure do not affect the mode shape, but the natural frequency of higher mode shape is sensitive to the change of the inflation pressure. The mode shapes of the grounding tire become asymmetric due to the effect of the vertical load, and the frequency of each mode has a mutation when the vertical load is larger than 3000 N. It is in good agreement between the FEA and experimental results of the free suspension tire.

Study on Contact Characteristics of Free Rolling Radial Tire

To study the rolling properties of a radial tire, an accurate 3D 195/60R14 tire model is established. The modal includes the geometric nonlinearity due to large deformation, material nonlinearity, the anisotropy of rubber-cord composites, the nonlinear boundary conditions from tire-rim contact and tire-pavement contact. The model can be used to simulate the changes of a rolling tire and calculate the tire deformation for various operating conditions. The profile of the inflated tire is studied experimentally and numerically. The simulation result is in good agreement with the test result. Some contact problems, such as the tire deformation, the shape of contact area, the contact pressure distribution, are discussed in detail.

Influence of Camber Angle on Rolling Radial Tire under Braking State

To study the rolling properties of a radial tire, an accurate 3D 195/60R14 tire model is established. The modal includes the geometric nonlinearity due to large deformation, material nonlinearity, the anisotropy of rubber-cord composites, the nonlinear boundary conditions from tire-rim contact and tire-pavement contact. The model can be used to simulate the changes of a rolling tire and calculate the tire deformation for various operating conditions. The profile of inflated tire is studied experimentally and numerically. The simulation result is in good agreement with the test result. Some contact problems, such as the tire deformation, the shape of contact area, the contact pressure distribution, are discussed in detail.

3-Dimensional non-linear FEM modeling and analysis of steady-rolling of radial tires

The 3D finite element method modeling based on MSC.MARC software was studied and a non-linear FEM model was developed. The non-linear mechanical properties of elastomers were described by the Mooney—Rivlin model. The rebar model was employed to simulate complex multilayer rubber—cord composites and directly define the cord directions varying with their positions. The radial tire model was established based on consideration of the geometric non-linearity due to large deformation, the material’s non-linearities of cord—rubber composites, the non-linear boundary conditions from tire—rim contact and tire—road contact. The steady-rolling performance of 195/60R14 radial tire was analyzed numerically. Under free-rolling state, centrifugal force had a certain effect on the contact performance of the radial tire. Under load rating, the stiffness of tire increased with the increase of the rotary speed. Under braking state, high stress region moves to the direction contrary to the running direction. The high stress region moves to the running direction under driving state. Compared with braking condition, the level of normal stress and friction stress in the contact region was higher under the driving conditions. Cord equivalent stress of the tire belt was larger near the tire shoulder, and smaller in the center of contact zone. Cord equivalent stress increased sharply with the rotary speed. Meanwhile, the maximum cord equivalent stress was higher under the driving state. The gradient of strain energy density near the belt end was larger. The strain energy density of the tire shoulder was the largest.

Prediction of the fatigue life of pneumatic tires

A method of the prediction of the fatigue life for parts of pneumatic tires based on the computation of the stress-strain state of the stress concentration areas in a rubber matrix and the self-heating temperature by means of the finite-element method and experimental fatigue curves for rubbercord composites has been developed. Multiple tensile tests of single-layer rubber-cord samples with a squared shape have been carried out, and fatigue curves under various test conditions and types of stress-strain states have been constructed. The fatigue life of the area of the edges of a breaker strip of a 9.00R20HC12 tire under a maximum working load and other parts of pneumatic tires is determined.