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Abstract
Tire cornering properties in non-steady state conditions (NSSC) are analyzed and reviewed in the aspects of theory, test and simulation. Based on the established tire models of cornering properties in steady state conditions, theoretical tire models of cornering properties in NSSC are established with complex deformations of carcass under consideration. Tire cornering tests in NSSC are carried out in a platform-type tire test rig. Then four structural parameters in the derived tire models are identified. Numerical simulations in spatial domain can be realized under different kinds of operation conditions according to the simulation algorithm derived from the initial integral expressions of the derived tire models. The theoretical results show good agreements with test data both in frequency domain and in spatial domain. The presented models and simulation data can be applied to analysis and simulation of vehicle dynamics.
... Substituted with equations (2), (10), and (11), the directional friction coefficient for calculating the extreme value of the resultant force can be derived from equation (17) as: ...
... Expanding the E-function expressions to Taylor's series, and neglecting the higher-order terms of s, equation (44) can be simplified as [9][10][11]: ...
UniTire is a unified non-linear and non-steady tire model for vehicle dynamic simulation and control under complex wheel motion inputs, involving large lateral slip, longitudinal slip, turn-slip, and camber. The model is now installed in an ADSL driving simulator at Jilin University for studying vehicle dynamics and their control systems. In this paper, first, a brief history of UniTire development is introduced; then the application scope of UniTire and available interfaces to MBS software are presented; thirdly, a more detailed description of UniTire is given; fourthly, a tool aiming at parameterization of UniTire is also demonstrated; and finally, some comments on TMPT are made.
... The tire lateral transient model is shown in Figure 3 [20,21]. First, the following assumptions are proposed: ...
Combined with the tire dynamics theoretical model, a rapid test method to obtain tire lateral and longitudinal both steady-state and transient characteristics only based on the tire quasi-steady-state test results is proposed. For steady state data extraction, the test time of the rapid test method is half that of the conventional test method. For transient tire characteristics the rapid test method omits the traditional tire test totally. At the mean time the accuracy of the two method is much closed. The rapid test method is explained theoretically and the test process is designed. The key parameters of tire are extracted and the comparison is made between rapid test and traditional test method. The result show that the identification accuracy based on the rapid test method is almost equal to the accuracy of the conventional one. Then, the heat generated during the rapid test method and that generated during the conventional test are calculated separately. The comparison shows that the heat generated during the rapid test is much smaller than the heat generated during the conventional test process. This benefits to the reduction of tire wear and the consistency of test results. Finally, it can be concluded that the fast test method can efficiently, accurately and energy-efficiently measure the steady-state and transient characteristics of the tire.
... Expanding the E-function expressions in a Taylor series, and neglecting the higher-order terms ofs. equation (38) can be simplified as [18][19][20][22][23][24] E{s)^as. AEy{s)^as. ...
The UniTire model is a nonlinear and non-steady-state tyre model for vehicle dynamics simulation and control under complex wheel motion inputs involving large lateral slip, longitudinal slip, turn slip and camber. The model is now installed in the driving simulator in the Automobile Dynamic Simulation Laboratory at Jilin University for studying vehicle dynamics and their control systems. Firstly, the nonlinear semiphysical steady-state tyre model, which complies with analytical boundary conditions up to the third order of the simplified physical model, is presented. Special attention has been paid to the expression for the dynamic friction coefficient between the tyre and the road surface and to the modification of the direction of the resultant force under combined-slip conditions. Based on the analytical non-steady-state tyre model, the effective slip ratios and quasi-steady-state concept are introduced to represent the non-steady-state nonlinear dynamic tyre properties in transient and large-slip-ratio cases. Non-steady-state tyre models of first-order approximation and of high-order approximation are developed on the basis of contact stress propagation processes. The UniTire model has been verified by different pure and combined test data and its simulation covered various complex wheel motion inputs, such as large lateral slip, longitudinal slip, turn slip and camber.
With the development of environmentally friendly “green tires” in the tire industry, silica has been used as a reinforcing filler material in tread compounds. With regard to this rubber compounding process, non-toxic, and renewable processing aids are required. We fabricated such processing aids with multi-alcohol components of hydrophobic and hydrophilic groups (M-A-S) to make the hydrophilic silica compatible with the hydrophobic rubber matrix. The rubber composites with M-A-S showed remarkable enhancements in the mechanical properties, specifically the tensile strength, elongation and fatigue properties due to the improved dispersion of silica in the rubber matrix. They also exhibited outstanding heat build-up, good rebound resilience, and abrasion levels at low loadings. Furthermore, M-A-S were added directly to tread compounds to make a pneumatic tire with enhanced high-speed durability and enhanced dry and wet braking due to the strong interfacial interaction between the silica and the rubber matrix. These results demonstrate the advantages of the proposed potential replacement for metal-ion processing aids for tire engineering.
Most parallel hybrid electric vehicles (HEV) employ both a hydraulic braking system and a regenerative braking system to provide
enhanced braking performance and energy regeneration. A new design of a combined braking control strategy (CBCS) is presented
in this paper. The design is based on a new method of HEV braking torque distribution that makes the hydraulic braking system
work together with the regenerative braking system. The control system meets the requirements of a vehicle longitudinal braking
performance and gets more regenerative energy charge back to the battery. In the described system, a logic threshold control
strategy (LTCS) is developed to adjust the hydraulic braking torque dynamically, and a fuzzy logic control strategy (FCS)
is applied to adjust the regenerative braking torque dynamically. With the control strategy, the hydraulic braking system
and the regenerative braking system work synchronously to assure high regenerative efficiency and good braking performance,
even on roads with a low adhesion coefficient when emergency braking is required. The proposed braking control strategy is
steady and effective, as demonstrated by the experiment and the simulation.
Modelling of the generation of shear forces by pneumatic tyres under steady state conditions is reviewed. The review is placed in a practical context, through reference to the uses to which models may be put by the vehicle dynamicist and the tyre designer. It will be of interest also to the student of rolling contact problems.The subject is divided into sections, covering physically founded models which require computation for their solution, physically based models which are sufficiently simplified to allow analytical solutions and formula based, empirical models. The classes are more nearly continuous than this strict division would imply, since approximations in obtaining analytical solutions may be made, empirical correction factors may be applied to analytical results and formula based methods may take into account tyre mechanical principles. Such matters are discussed in the relevant sections. Attention is given to the important matter of choosing model parameters to best represent the behaviour of a particular tyre.Conclusions relate to the structural and frictional mechanisms present in the shear force generation process, the contributions of carcass and tread elastic properties and of geometrical and frictional factors to the determination of the distributions of force through the contact region, the relationship between accuracy and computational load and the selection of methods for modelling tyre forces in a road vehicle dynamics context. Reference to the most pertinent literature in the field is made and possibilities for the further development of the state of the art are mentioned.
Tire tests were performed under time‐varying inputs on the Calspan Tire Research Facility with a G78‐14 belted tire at low speeds and path frequencies up to 6 rad/ft (20 rad/m). Both slip angle and vertical load were varied, either separately and periodically or in combination. The combination simulated actual time histories of slip angle and load measured in road accident avoidance tests.
For path frequencies up to 0.2 rad/ft (0.7 rad/m), attenuation of lateral force and aligning torque amplitudes was negligibly small. However, both lagged static values substantially, leading to dynamic offsets in these quantities. The offsets appeared to be the most significant factors for tires. Their effect on the dynamic response of a vehicle remains to be investigated.
A theoretical model of nonsteady state tyre cornering properties (NSSTCP) with small lateral inputs and its experimental validation are presented. The flexibility of carcass composed of translating, bending and twisting parts is considered. Tyre structure parameters in the model can be simplified as four nondimensional factors which associate with stiffness of tread and carcass, tyre width, length of contact patch respectively The tests of NSSTCP including pure yaw motion and pure lateral motion are designed and realized by step lateral inputs. Then the structure parameters are identified according to the expressions of the analytical model and frequency response data resulting from the test data in spatial domain. The derived model is validated by experiment results.
During the last decade research has been conducted on the dvnamics of the tvre considered as a vehiclecomponent. Asurvey is given of these developments where tyre mass plays an important role. The underlying theoretical considerations concerning the massless tyre have been discussed as well. Two groups of tyre response have been distinguished: the lateral (out-of-plane) response and the vertical/longitudinal (in-plane) response to motions of the wheel. In both categories tyre compliance, slip and inertia have influence. The dynamic properties of the rolling tyre have been presented in the form of transfer functions and/or differential equations. The frequency of the imposed oscillations is assumed to be below ca. 40 Hz. Non-linear effects and modelling have been briefly touched on.
A research program has investigated the use of the von Schlippe string-type tire model for predicting the dynamic behavior of aircraft tires. The transfer-function method was used for theory evaluation. A more flexible two-constant modification to the string theory tire model is presented. Experiments were conducted on four types of scale model aircraft tires. Two types were of conventional bias construction, one type was an isotropic toroid, and one type was of unbelted radial construction. The conventional string theory and model gave predictions that were in good agreement with experimental data for bias constructed tires. The two-constant modification to string theory provided better agreement between predictions and experiment for the unconventional tires. The results indicate that the string theory tire model using static and slow-rolling tire properties predicts dynamic aircraft tire properties that have the same trends as the measured dynamic properties and, in most cases, provides good quantitative agreement.