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Semi-active suspensions are important components for improving vehicle ride comfort. In this paper, a new road unevenness classification method that is based on tread band vibrations is proposed. Moreover, this method is implemented in the control algorithm of a semi-active suspension with a magnetorheological damper (MRD). The core contributions of this paper include establishing the simulation environment for the tread band vibration based on the rigid-flexible coupling ring tire model and the hardware testing platform based on an intelligent tire and a 1/4 vehicle vibration bench. In this testing platform, an intelligent tire sensor is installed in the tire to reflect the tread band vibration. The comparison of different machine learning algorithms and measured accelerations indicates the effectiveness of using the decision tree algorithm and the tread band vibration for road classification. Furthermore, a hardware architecture is proposed in this paper for real-time communication between wirelessly transmitted intelligent tire acceleration signals and a suspension controller, achieving online classification and adaptive adjustment of the optimal control parameters for the semi-active suspension. In summary, intelligent tires and suspension control systems are successfully integrated in this study, providing the possibility and basis for developing more complex general chassis control systems that include intelligent tires. [ABSTRACT FROM AUTHOR]

Cylindrical shells are widely used in engineering practice; in particular, one of the special applications is a tire, which can be modeled as a cylindrical shell on an elastic foundation (CSEF). To investigate influences of related parameters on the dynamic characteristics of the shell and help engineers to gain insights into the tire dynamics, a unified formulation for vibration analysis of the cylindrical shell with general boundaries has been developed; this unified formulation includes (i) formulations for CSEF governing equations based on the Donnell-Mushtari theory and Hamilton’s principle; (ii) a unified approach for the solutions of the characteristic equation; and (iii) a general treatment of the boundary conditions by adjusting the foundation spring coefficients. All nine sets of possible solutions of the characteristic equation are clarified and examined. Five case studies have been conducted to validate and verify the developed algorithm. The results based on the developed method generally have good agreement with those of the finite element method and experiment; missed solutions can be recovered. [ABSTRACT FROM AUTHOR]

A new adjoint shape design sensitivity formulation for nonlinear structures subject to contact forces is developed. The method is based on a geometrical mapping approach where shape variation is regarded as a mapping characterized by the shape variation velocity field. An adjoint variable method is developed for performing sensitivity analysis of the average shear strain in the tire belt area, which profile is properly parameterized in function of arcs, allowing explicit design velocities calculated. It can be seen that the present method is much faster than the direct differentiation method and more accurate than the classical finite difference scheme. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to propose a method to simulate the polytropic process of air springs.Design/methodology/approach An iterative finite element method (FEM) is proposed.Findings The proposed method is reliable and effective in solving the polytropic process of air springs.Originality/value This work would be helpful for understanding the simulation of pneumatic structures, and the proposed modified FEM would be useful for improving the simulation of the mechanical behavior of an air spring. [ABSTRACT FROM AUTHOR]

It is well known that the tyre steering torque is highly dependent on the tyre rolling speed. In limited cases, i.e. parking manoeuvre, the steering torque approaches the maximum. With the increasing tyre speed, the steering torque decreased rapidly. Accurate modelling of the speed-dependent behaviour for the tyre steering torque is a key factor to calibrate the electric power steering (EPS) system and tune the handling performance of vehicles. However, no satisfactory theoretical model can be found in the existing literature to explain this phenomenon. This paper proposes a new theoretical framework to model this important tyre behaviour, which includes three key factors: (1) tyre three-dimensional transient rolling kinematics with turn-slip; (2) dynamical force and moment generation; and (3) the mixed Lagrange–Euler method for contact deformation solving. A nonlinear finite-element code has been developed to implement the proposed approach. It can be found that the main mechanism for the speed-dependent steering torque is due to turn-slip-related kinematics. This paper provides a theory to explain the complex mechanism of the tyre steering torque generation, which helps to understand the speed-dependent tyre steering torque, tyre road feeling and EPS calibration. [ABSTRACT FROM PUBLISHER]

[Display omitted] • The proposed ELM model is a new universal rheological model for non-Newtonian fluids. • The ELM model captures both nonlinearities of MRFs in small and large shear rates. • Model splitting efficiently identifies the model parameters with a physical background. • The ELM model can be reduced to the Bingham and Papanastasious models. • Application to the magnetic effect modeling and design simulation demonstrated. As an intelligent material, the magnetorheological fluid (MRF) has increased use in various fields, e.g., the semi-active suspension of vehicles. However, the efficient utilization and optimization of MRFs depend on a reliable constitutive relationship over a wide shear rate range, which existing models cannot fully and satisfactorily explain. This paper proposes a new non-Newtonian fluid constitutive equation that combines exponential and linear terms to describe the general characteristics of MRFs to tackle this problem. An effective parameter identification approach is realized by adopting model splitting to reduce the dimension of the optimized parameter space combined with a reasonable initial guess. A well-designed experiment for a commercial MRF is conducted to verify the proposed constitutive equation, indicating an improvement in accuracy of approximately 43 % compared with the Herschel-Bulkley model and its capability to reveal the rheological behaviors of MRFs in the wide shear rate range of 0.3–30000 s−1. The high compatibility between the proposed model and the Bingham model is supported by the high correlation coefficients of the dynamic yield stress and viscosity coefficient identified by this model and the existing data processing method based on the Bingham model, 0.9949 and 0.9160, respectively. Owing to its decoupled parameter structure, the extension to a multivariable framework has been implemented to consider the magnetorheological effect with good agreement. Finally, the application of magnetorheological device design has demonstrated the versatility and capacity of the proposed model for developing and utilizing a new generation of MRFs. [ABSTRACT FROM AUTHOR]

It is well known that the tyre steering torque is highly dependent on the tyre rolling speed. In limited cases, i.e. parking manoeuvre, the steering torque approaches the maximum. With the increasing tyre speed, the steering torque decreased rapidly. Accurate modelling of the speed-dependent behaviour for the tyre steering torque is a key factor to calibrate the electric power steering (EPS) system and tune the handling performance of vehicles. However, no satisfactory theoretical model can be found in the existing literature to explain this phenomenon. This paper proposes a new theoretical framework to model this important tyre behaviour, which includes three key factors: (1) tyre three-dimensional transient rolling kinematics with turn-slip; (2) dynamical force and moment generation; and (3) the mixed Lagrange–Euler method for contact deformation solving. A nonlinear finite-element code has been developed to implement the proposed approach. It can be found that the main mechanism for the speed-dependent steering torque is due to turn-slip-related kinematics. This paper provides a theory to explain the complex mechanism of the tyre steering torque generation, which helps to understand the speed-dependent tyre steering torque, tyre road feeling and EPS calibration. [ABSTRACT FROM PUBLISHER]

By using a hybrid displacement discontinuity method and a generalization of Bueckner’s principle, the interactions of two collinear square-hole cracks in an infinite plate in tension are investigated in this paper. Numerical examples are included to illustrate that the numerical approach is very effective for analyzing multiple-hole cracks in an infinite plate in tension. Many numerical results are given and discussed. It is found that a square hole has a shielding effect on crack(s) emanating from the hole. The finding perhaps has an important meaning in engineering. [ABSTRACT FROM AUTHOR]

Abstract: By using a hybrid displacement discontinuity method, the interactions of two collinear circular hole cracks in infinite plate subjected to internal pressure are investigated in this paper. Numerical examples are included to illustrate that the numerical approach is very simple and effective for calculating the stress intensity factors (SIFs) of crack problems. In particular, the interaction problem of two collinear circular hole cracks is investigated in detail. Many numerical results are given and discussed. It is found that a circular hole has a shielding effect on the SIFs of crack(s) emanating from the hole. The finding perhaps has an important meaning in engineering. [Copyright &y& Elsevier]

A new method to describe tyre rolling kinematics and how to calculate tyre forces and moments is presented. The Lagrange–Euler method is used to calculate the velocity and contact deformation of a tyre structure under large deformation. The calculation of structure deformation is based on the Lagrange method, while the Euler method is used to analyse the deformation and forces in the contact area. The method to predict tyre forces and moments is built using kinematic theory and nonlinear finite element analysis. A detailed analysis of the tyre tangential contact velocity and the relationships between contact forces, contact areas, lateral forces, and yaw and camber angles has been performed for specific tyres. Research on the parametric sensitivity of tyre lateral forces and self-aligning torque on tread stiffness and friction coefficients is carried out in the second part of this paper. [ABSTRACT FROM PUBLISHER]

There are two aims for the second part of this paper: verifying the theory presented in the first part through parameter variation and comparison between simulation and experiment, and to study the effect of the belt structure on the cornering properties of radial tyres. Research has been carried out with a passenger car radial tyre and two different kinds of truck or bus radial tyres using both simulation and experiment. This second part of the paper shows that belt structure plays an important role in the generation of tyre forces and moments in addition to the effects of the tread stiffness and friction coefficients. The theory and method presented in this paper opens a new robust way to predict the tyre forces and moments from the tyre design and provides a reliable model for a generation mechanism. [ABSTRACT FROM PUBLISHER]

Abstract: In order to calculate the contribution of out-of-plane stresses and strains to laminate structural modal damping in FEM with fewer elements in thickness direction, composite structural modal damping prediction theory based on 3-D effective damping matrix is presented in this paper. First, the composite structure is divided into several sublaminates along the thickness, and each sublaminate contains many laminas. These sublaminates’ stiffness matrices, compliance matrices and 3-D effective damping matrices are calculated by lamination theory. Then finite elements are generated with these sublaminates, and structural modal analysis is implemented. Combining the 3-D effective damping matrices and the results of modal analysis, specific damping capacities for each modal are calculated. The presented method is validated by the calculations for structural SDCs of unidirectional laminate, symmetrical laminate and thick laminate. This method combines the accuracy and efficiency with the consideration of out-of-plane stresses and strains contribution. [Copyright &y& Elsevier]

• Proposal for estimating road friction coefficient directly from image. • A texture-aware classification model adapted to road surface image. • A mapping method links friction class and friction coefficient. • Post-processing scheme that filters the estimation output. • Real-vehicle validations and analyses in variable scenarios. Road peak friction is a significant parameter determining vehicle driving safety. This paper focuses on road friction monitoring based on vision for autonomous vehicles. A deep learning classification model combined with training strategies adapted to the real-scenario road friction image dataset is proposed. The road peak friction coefficient is initially derived based on the classification probability and an empirical inference model. To enhance the usability and reliability of the estimated friction coefficient, a filter that concerns the classification model uncertainty and the variation of estimation output is then performed. The top-1 and top-2 classification accuracy on five road friction classes reach 94.84% and 99.22%, respectively. The developed friction preview scheme is further deployed and validated in real-vehicle scenarios. The results indicate that the proposed methods are robust to road environment change. It has potential in practical applications that provide crucial road information for safer autonomous driving. [ABSTRACT FROM AUTHOR]

A novel constitutive characterization method for uncured rubber behaviour has been developed in this article. A systematic measuring procedure was designed to fully investigate the uncured rubber complex stress–strain behaviour under different deformation patterns, which integrated three kinds of tests – the uniaxial tensile, the compression test and the shear test. It can be found from the observed behaviour that the uncured rubber has similar but much pronounced non-elastic stress–strain relationship, which is highly non-linear and highly rate dependent. A generalized Maxwell model with modified Yeoh model is developed to constitutively describe the observed phenomena in which parameters are identified by an evolution optimization scheme. Good agreement can be found between the model and the test data. Another finding is that, similar to vulcanized rubber, multi-test data are needed to obtain compatible constitutive models. The test results, findings and the developed model help rubber engineers deeply understand the uncured rubber's mechanical behaviour and provide a base for rubber manufacturing simulation. [ABSTRACT FROM AUTHOR]

As a smart material with controllable rheological properties, magnetorheological fluids (MRFs) have been increasingly used in various fields. The temperature of MRFs inevitably changes during operation, which markedly affects the rheological properties; thus, the modeling of temperature effects is critical for the control and design of magnetorheological devices. However, most studies only examine the temperature effects of MRFs in a narrow temperature range, which fails to effectively cover the operating temperature range of MRFs, and the viscosity-temperature models used have notable limitations. This paper proposes to use free volume theory, in the form of the universal Doolittle equation, to study the viscosity-temperature behavior of MRFs and their base oils over a wide temperature range. Compared with the existing Reynolds and Arrhenius equations, the Doolittle equation achieves an accuracy improvement of up to 17 times and eight times, respectively. It predicts the overall viscosity-temperature behavior of liquids based on four data points taken over a narrow temperature range, with a relative root-mean-square error (RMSE) of no more than 5%. Ignoring the limited effect of off-state yield stress, the Doolittle equation with strong expandability can be used to establish temperature-dependent MRF constitutive equations. It can even develop multiphysics models based on the highly similar viscosity-temperature characteristics between MRFs and their base oils, which will greatly facilitate the development and optimization of MRFs. [ABSTRACT FROM AUTHOR]

Magnetorheological fluid (MRF) is a widely used smart material that suffers from sedimentation. Since sedimentation is unavoidable, it is crucial to study and improve the redispersibility of MRFs. However, previous redispersibility testing methods have problems, such as complicated operation and low precision. Simultaneously, a simple and effective method is urgently needed for high-precision modeling of MRF sedimentation to test the rheological properties of settled MRFs at different depths. After systematically analyzing the redispersion problem, this paper proposes decoupling the energy required for redispersing settled MRFs into two parts, which are related to different factors. These two parts are the energy required to separate the agglomerated particles (related to the MRF formula) and that to redisperse the settled MRF uniformly vertically against gravity (related to the solid concentration and packing limit). The energy that separates the agglomerated particles is proportional to the shear stress of slowly shearing the corresponding agglomerated samples, i.e., the yield stress. Thus, this paper proposes a simple microdamage quasi-static indentation method to measure the yield stresses of settled MRFs at different depths to characterize the redispersibility of the corresponding MRFs. Herein, this method is applied to study the mechanisms of the influences of surfactants, thixotropic agents, and their networks on the redispersibility of MRFs. The results indicate that a well-dispersed plate-like thixotropic agent network can effectively improve redispersibility, while surfactants with poor compatibility degrade redispersibility. In summary, this redispersibility test method will greatly facilitate studies of MRFs, such as optimizing the formulas and establishing sedimentation models. [ABSTRACT FROM AUTHOR]

A radial tire is a very complex structure made from rubber elastomers and fiber–rubber composite materials. During its use, extension propagation of interface crack between belts can occur, which obviously affects its durability and life. In the present paper, a new mathematical model of extension propagation of interface crack in complex composite structures is presented. The model can reveal the extension propagation dependence of interface crack on the relative size of energy release rates at the left and right crack tips and on the interfacial material properties. The extension propagation model of interface crack, Irwin’s virtual crack close technique and the finite element analysis method are used together in simulating numerically the extension propagation process of a interface crack between belts of a radial tire. The present study numerical results show that the extension propagation model of interface crack proposed in this paper can more realistically characterize the complexity of the extension propagation process of interface crack in complex composite structures. [Copyright &y& Elsevier]

Material and geometrical parameters of tires involve some degree of uncertainty mainly related to production processes. Accordingly, the associated structural responses are affected by these uncertainties. In this study, a novel theoretical ring model is presented to describe the in-plane and out-of-plane vibrations as well as the steady-state response of tires, and then to evaluate the influence of the uncertainties in structural parameters on the natural frequencies and the sound radiation characteristics under uncertain excitations. The Hamilton principle is applied here to derive the governing equations. The modal superposition method is used to calculate the steady-state response of the tire. In the sound radiation analysis, the in-plane and out-of-plane bending and torsional vibrations under a set of harmonic unit forces and moments are treated as the source of noise generation. On this basis, the generalized polynomial chaos expansion method is then adopted to evaluate the influence of the uncertainty on the natural frequencies and the sound power. To obtain the unknown coefficients of the expansions, the nonintrusive probabilistic collocation method is employed. Moreover, considering the concept of linear independence of vectors, the number of collocation points is reduced. It is applied to investigate the impacts of the elastic and structural uncertainties on the natural frequencies of the tire. This yields an efficient simulation in terms of computational costs. Finally, the distributions of the sound power due to the forced vibration under the random concentrated line forces are given. [ABSTRACT FROM AUTHOR]

Magnetorheological (MR) damper is one of the key technologies in the field of semi-active suspensions. However, the dynamic model and control strategy are not yet well established. A unified MR damper model and its inverse characterization are proposed to investigate MR damper dynamics. First, a novel unified model is proposed to describe the shear term of the MR damper force. This forward unified MR damper model uses one set of parameters to describe all MR force behavior under all currents and velocities, which agrees well with experimental data. Then, an inverse MR model based on the adaptive neuro-fuzzy inference system (ANFIS) technique has been established, where the precise training data are obtained from the proposed unified hysteretic model. A clear step-wise modeling process is proposed to decrease coupling degree of system which can be beneficial to improve inverse modeling efficiency. The inverse MR model is used for a semi-active suspension control, which can obtain the excitation current, exactly tracking the desired damping force computed by suspension control algorithm. Finally, validation of the proposed ANFIS inverse model has been conducted by comparison with three traditional empirical inverse approaches. The results reveal that the ANFIS inverse model could achieve much more tracking capability for the desired damping force and thus contributes to the development of semi-active suspension controllers. [ABSTRACT FROM AUTHOR]

Tire uniformity is defined as the dynamic mechanical characteristics of pneumatic tires due to the defects originating in tire components during manufacturing processes. These defects lead to deviations in the structural and material parameters of tires and, in turn, induce variations in the dynamic response. In this scenario, this paper proposes a probabilistic model of the low-speed uniformity analysis for predicting the impacts of the uncertainties in the geometric defects and the vertical load on the dynamic responses. The deterministic coupled rigid–flexible ring model, combined with the generalized polynomial chaos expansion theory, is developed to simulate the radial force variation due to radial run-out. In this approach, the non-uniform tire radius and the vertical load are selected as a set of random variables and are approximated by the generalized polynomial chaos expansions. The distributions of these input variables are identified from 200 measured tires by the Pearson model. A non-intrusive probabilistic collocation method is adopted to evaluate the coefficients of the generalized polynomial chaos expansions, and the selection of collocation points is also illustrated. Finally, the distributions of the radial force variation and its first harmonic due to the geometric defects and vertical loads are predicted in comparison with measurements. Moreover, the distributions of the dynamic response caused by each parameter and different variance levels are discussed and verified by the measurement data from 1130 tires. • An effective model for the stochastic analysis of low-speed tire uniformity is presented. • The distributions of uncertain inputs are identified from measurement data. • The improved collocation point selection method is experimentally verified. • The distribution of radial force variations due to run-outs and loads is simulated. • The impacts of each parameter and different variance levels are given and validated. [ABSTRACT FROM AUTHOR]

The dynamic response of tires directly affects the handling stability and ride comfort of a vehicle, which in turn determines the vehicle ride, handling, and driver perception. Modeling and simulation of tire dynamics typically require a reasonable computational cost while ensuring proper accuracy. In this study, a novel theoretical model, the coupled rigid–flexible ring model, is presented to analyze the characteristics of the in-plane dynamic responses of tires on uneven road surfaces. The proposed new method consists of three primary sub-models: an elastic contact algorithm featured by a flexible ring model, rolling/vibration dynamics represented by a rigid ring model, and an internal-force transmission algorithm linking the rigid and flexible ring models. In this way, the proposed new method has the merits of both high accuracy up to 150 Hz and low computing cost. A contact algorithm based on the two-dimensional flexible ring provides a pressure distribution on the tire–road contact patch and the length of the footprint under different vertical loads. The transient dynamic response is then estimated by combining the rigid ring model with the flexible ring model. The accuracy of the contact algorithm and the transient responses are validated against experimental radial stiffness and the over-cleat tests respectively. The results show that the in-plane dynamics of the tire can be predicted well. In addition, this model is extended to the analysis of the low-speed uniformity of tires with geometric defects and is validated experimentally. It indicates that the novel proposed model offers many application scenarios and extension possibilities. • A novel coupled rigid–flexible ring model is presented to analyze tire dynamics. • Parameter identification and optimization are implemented by full-scale measurements. • The accuracy of the contact algorithm and transient responses is verified by tests. • The analysis of low-speed uniformity of tires with geometric defects is achieved. • The proposed model offers many application scenarios and extension possibilities. [ABSTRACT FROM AUTHOR]

[Display omitted] • All study is based on and validated by proving ground experiment. • Real time identification with acceleration by LSTM network is proposed. • A section of serial acceleration signal without preprocessing is needed. • Identification is robust to different velocity and damping with high accuracy. • Damping is adaptive to current road conditions. Road unevenness provides essential evidence for semi-active suspension control while it is difficult to estimate accurately in real time. This paper proposes a real-time method of identifying road unevenness with serial acceleration signals and unevenness-correlated adaptive suspension damping control. This new method uses Long Short-Term Memory (LSTM) network to identify the characteristics of the time domain signal and classify it into different unevenness classes. A proving ground experiment is designed and conducted to construct and validate the algorithm. The good estimation accuracy and robustness is realized at different vehicle velocities and suspension damping levels. Based on this real-time estimated road unevenness, the developed suspension controller can be enhanced by adaptive correlation of the comfort weight and adaptive damping coefficient with corresponding road unevenness. A calibration experiment is conducted to provide evidence for comfort weight selection. The validation experiment result proves that the adaptive damping control could substantially reduce RMS of body acceleration on different kinds of roads, demonstrating the effectiveness of the proposed new method. [ABSTRACT FROM AUTHOR]

• Isogeometric analysis with high order continuity for tire analysis is presented. • Unclamped B-splines define a circle with high accuracy and full continuity. • Derivatives of B-spline basis functions are computed efficiently. • Steady-state rolling in IGA considers higher order gradients straightforwardly. • Comparison and validation by means of experiments. The analysis of rolling tires using numerical methods sheds light on the understanding of complex phenomena, while reducing the amount of experimental tests, which are used to calibrate and validate the models. Among different approaches, the finite element method is often used in tire industry, due to its capabilities of describing structural behavior, where material properties and an accurate geometry are required. Isogeometric Analysis offers an efficient and exact geometrical description of bodies, in contrast e.g. to linear finite elements, which is fundamental for the circular shape of a tire. In this contribution, a novel framework for tire analysis is presented. Closed unclamped B-splines are employed for a fully continuous description of geometry and field variables. The overall high-order continuity of the model allows the analysis to be less sensitive with respect to the applied discretization which becomes obvious in comparison to standard FEA models. The rolling phenomenon is described by an Arbitrary L agrangian –E ulerian approach with a direct computation of second order gradients due to the use of higher order basis functions. This novel framework is validated by experiments using a passenger car tire, where accelerations are registered. This versatile approach can be employed for the comparison and evaluation of analytical approaches. A discussion of the results of numerical simulations, significant remarks and an outlook on further research directions close this presentation. [ABSTRACT FROM AUTHOR]