Abstract: While in the automotive field the relationship between road adherence and tire temperature is mainly investigated with the aim to enhance the vehicle performance in motorsport, the motorcycle sector is highly sensitive to such theme also from less extreme applications. The small extension of the footprint, along with the need to guarantee driver stability and safety in the widest possible range of riding conditions, requires that tires work as most as possible at a temperature able to let the viscoelastic compounds-constituting the tread and the composite materials of the whole carcass structure-provide the highest interaction force with road. Moreover, both for tire manufacturing companies and for single track vehicles designers and racing teams, a deep knowledge of the thermodynamic phenomena involved at the ground level is a key factor for the development of optimal solutions and setup. This paper proposes a physical model based on the application of the Fourier thermodynamic equations to a three-dimensional domain, accounting for all the sources of heating like friction power at the road interface and the cyclic generation of heat because of rolling and to asphalt indentation, and for the cooling effects because of the air forced convection, to road conduction and to turbulences in the inflation chamber. The complex heat exchanges in the system are fully described and modeled, with particular reference to the management of contact patch position, correlated to camber angle and requiring the adoption of an innovative multi-ribbed and multi-layered tire structure. The completely physical approach induces the need of a proper parameterization of the model, whose main stages are described, both from the experimental and identification points of view, with particular reference to non-destructive procedures for thermal parameters definition. One of the most peculiar and challenging features of the model is linked with its topological and analytical structure, allowing to run in real-time, usefully for the application in co-simulation vehicle dynamics platforms, for performance prediction and setup optimization applications.

Abstract: A non-pneumatic tyre (NPT) is a novel type of safety tyre that is designed to provide similar elastic properties to those offered by conventional pneumatic tyres. The main advantage of NPT is the lack of compressed air (like in a pneumatic tire) to ensure adequate traction forces and directional control. Suitable materials and the appropriate geometry of the supporting structure allows to achieve properties provides by pneumatic tires. Flexible spokes and closed structure like honeycomb are the most common solutions of supporting structure. Appropriate geometry, thickness and materials of this part affect the NPT properties; radial stiffness, unit pressure in the contact patch and the parameters of an area in contact with a non-deformable surface. The paper presents the FEM NPT model (NPT_0), which was validated with the results of experimental research of NPT. The NPT_0 model is subject to further modifications (layout and shape of the radial spokes) was used in the study. Seven new geometries of NPT supporting structure were selected for simulation tests. During the numerical tests the radial stiffness, unit pressure in the contact patch and the parameters of an area in contact with a non-deformable surface were determined. It has been observed that an increase in the curvature of the spokes reduced radial stiffness and increased the length of the contact path.

Abstract: This investigation was motivated by the need for performance improvement of pneumatic tires in icy conditions. Under normal operation, the pneumatic tire is the only force-transmitting com...

Abstract: The grip force of tires is crucial for vehicle security and drivability under different driving conditions. A small contact area and stress concentration in the contact patch of two-wheeled motorcycle (TWM) tires result in a reduction in grip performance and wear resistance. Even worse, improving the grip and wear resistance together is difficult to achieve. The purpose of the current study is to analyze the dynamic grounding characteristics and geometry of a cat paw pad and then apply its structure to the TWM tire to improve the contact area and wear resistance under different operating conditions. A nonlinear finite element tire model that could accurately reconstruct the tire structure and realistically reflect the mechanical response to different loads was employed. Then, the accuracy of the tire model was validated by a static test with a control tire. For cats, the dynamic grounding characteristics and topology of paw pads were determined using a pressure-sensitive walkway and a three-dimensional (3D) laser scanner. The results indicated that the cat forepaw third pad (CFTP) exhibited excellent grip capacity. According to similarity transformation, a bionic tire crown was designed according to the lateral fitting curve of the CFTP. Comparative results showed the enlargement of the contact area and decreases in peak pressure and frictional energy rate for the bionic tire under different conditions. With these improvements, the grip performance was improved, and the service life was extended synchronously. These research results can be applied for the design of TWM tires, especially cross-country motorcycle tires.

Abstract: The vehicle dynamic behaviour analysis is a crucial step for the evaluation of performance in terms of stability and safety Tires play an important role by generating the interaction forces at each road-tire contact patch The longitudinal and lateral dynamics are analysed by using instrumented vehicles with expensive high precision sensors to get a measurement of estimates of physical parameters of interest This paper deals with the evaluation of vehicle under/oversteering behaviour and of braking performance using a Real-time (RT) simulator The simulations were performed by using an efficient 15 Degrees of Freedoms (DOFs) Lumped-Parameter Full Vehicle Model (LPFVM), comprising a tire model with temperature-dependent properties A virtual Driver-in-the-Loop (vDiL) scheme was used to perform test manouvers The virtual driver is based on two PID regulators for speed and steering control Finally, this paper reports the results of constant radius tests as defined by standard ISO4138 and of a braking manoeuvre In both tests, a type-A road profile as defined by ISO 8608 standard was simulated

Abstract: The article deals with the mathematical model of wheel axle displacement after the end of the vehicle braking process on the uphill in the absence of moving the pneumatic tire contact patch relative to the road surface. The proposed dependencies for determining the coordinate of the wheel axis position and the speed of its movement on the basis of the general dynamics equation allow to determine the time during which the wheel axis deviates by the maximum distance from the axis of symmetry of the contact patch of the pneumatic tire, which is stationary relative to the surface of the pavement. The obtained simulation results made it possible to establish a relationship between the position of the wheel axis, the mass of the vehicle and the value of the longitudinal uphill of the pavement surface, and made it possible to evaluate the possibility of using the energy of the elastic deformation of the pneumatic tire at the moment when the vehicle started to moving on the uphill. The proposed mathematical model of rectilinear motion of the axle of the locked wheel, the contact patch of which does not move relative to the surface of the pavement, may be a theoretical basis for the analysis and synthesis of the algorithm for controlling the system of motion of the vehicle on the uphill.

Abstract: The tire establishes the contact between the vehicle and the road. It transmits all forces and moments to the road via its contact patch or footprint and vice versa. The visual inspection...

Abstract: Prosthetic and robotic grippers rely on soft finger pads to better acquire objects of varying size, shape and surface. However, the frictional behavior of soft finger pads of different designs and geometries have yet to be quantitatively compared, in large part due to the difficulty in modeling soft contact mechanics. In this letter, we experimentally examine the frictional behavior of several common primitive contact geometries in terms of their performance under shear loads that would tend to cause the contact to slip and the grasp to potentially fail. The effective static and kinetic coefficients of friction were recorded for each finger pad under a range of common grasping loads. The results show that the variance in contact curvature, contact patch geometry and pressure distribution have influences on key parameters for grasping at low forces. The advantages and disadvantages of these simple geometries are discussed for design of single finger, multi-finger and manipulation-based robotic hands.

Abstract: Wheel wear is unavoidable, which affects the contact performance of the wheel and rail. This article explores the effects of wheel profile wear on the static contact and dynamic interaction between wheel and standard fixed frog in heavy haul railway. The coupling dynamic models of the vehicle-fixed frog system are established to calculate the change regulation of displacement, contact force, and acceleration when a vehicle passes through the standard fixed frog at a speed of 50 km/h in the facing move in the diverging line. Besides, the finite element models of wheel and standard fixed frog at key positions are developed to simulate the contact patch and distribution of von Mises stress in the regions of the wheel-fixed frog. Compared with the standard profile, the maximum lateral displacement of the worn profile can be reduced by up to 9 mm. The vertical contact force can be reduced from 750 kN to 320 kN, and the decrease is 57.3%. The von Mises stress could decrease up to 34% compared with the standard. And the results show that the wheel profile wear changes the positions of the wheel-rail contact points along the longitudinal direction and affects the dynamic interaction of vehicle and standard fixed frog. For the measured worn wheel profiles in this article, profile wear relieves the dynamic responses and it is good for the nose rail.

Abstract: We present a principled method for motion prediction via dynamic simulation for rigid bodies in intermittent contact with each other where the contact region is a planar non-convex contact patch. Such methods are useful in planning and control for robotic manipulation. The planar non-convex contact patch can either be a topologically connected set or disconnected set. Most work in rigid body dynamic simulation assume that the contact between objects is a point contact, which may not be valid in many applications. In this paper, by using the convex hull of the contact patch, we build on our recent work on simulating rigid bodies with convex contact patches for simulating motion of objects with planar non-convex contact patches. We formulate a discrete-time mixed complementarity problem where we solve the contact detection and integration of the equations of motion simultaneously. We solve for the equivalent contact point (ECP) and contact impulse of each contact patch simultaneously along with the state, i.e., configuration and velocity of the objects. We prove that although we are representing a patch contact by an equivalent point, our model for enforcing non-penetration constraints ensure that there is no artificial penetration between the contacting rigid bodies. We provide empirical evidence to show that our method can seamlessly capture transition among different contact modes like patch contact, multiple or single point contact.

Abstract: A system for estimating a tire load of a tire includes a pressure sensor configured to generate a tire pressure signal; an acceleration sensor configured to generate a tire acceleration signal; a temperature sensor configured to generate a tire temperature signal; and at least one processor configured to calculate a duration of a contact patch based on the tire acceleration signal, calculate a vehicle speed based on the tire acceleration signal, determine at least one system model coefficient based on the tire pressure signal and the tire temperature signal, and calculate the tire load of the tire using a linear system model that relates tire pressure, the duration of the contact patch, and the vehicle speed to the tire load of the tire, where the linear system model further includes the at least one system model coefficient for calculating the tire load of the tire.

Abstract: The invention relates to an auto-location using tire mounted system. An auto-location system (190) for auto-locating a wheel in a vehicle is disclosed. The auto-location system (190) comprises: a sensor module (100) which comprises a sensor (110) adapted for sensing a physical property of the tire when mounted in a tire or on an inner surface of the tire of the wheel, an acquisition system (120) adapted for determining when the part of the tire where the sensor (110) is mounted hits the ground, and forms a contact patch with the ground, by analyzing data from the sensor (110), and a communication system (130) adapted for transmitting a wireless message, in which a unique identifier is embedded, a transmit delay after the part of the tire where the sensor is mounted hits the ground.

Abstract: A device for estimating a friction coefficient between a road surface and an automotive tire through determination of a steering torque during a steering maneuver of a slow-rolling or stationary vehicle includes a computer configured for constructing a brush model for a description of the steering torque across a contact patch between the tire and road surface. The steering torque is a torque acting on a steering axis required to overcome resistance to tire twisting on the road surface at a wheel velocity and a steering rate. The steering torque depends on a tire brush vertical load distribution and relative motion of tire brushes and the road surface. The device further includes sensors for measuring the wheel velocity and the steering rate and mechanism for measurements or estimation of the steering torque. The friction coefficient is estimated based on the measurements or estimation of the steering torque and the brush model.

Abstract: This paper focuses on the size of the machined contact surface on the wheel flange to clarify its influence on wheel climb derailment after wheel turning. To investigate transient characteristics between machined contact surfaces and smooth contact surfaces, tangential force experiments were carried out using a pair of small cylindrical specimens. Experimental results show that the coefficient of friction on the contact surface increases due to repeated rolling and sliding frictional force. The tangential force coefficient on the machined contact surface is small in comparison the same force measured on the smooth contact surface in the range of the slip ratio of less than about 1.0% due to the difference in the contact patch and surface properties, while the tangential force coefficient with both contact surfaces is almost the same in the range of a slip ratio of more than about 1.0%. This means that the influence of the machined contact surface on the steady and transient characteristics of the tangential force of the wheel/rail is small if only ordinary wheel turning is conducted.

Abstract: The invention relates to a device (1) for reducing the tyre noise of a vehicle (3) having at least one tyre (2), the tyre (2) rolling on a roadway on a contact patch (4), the device (1) comprising at least one sound absorption element (5), which is fastened to the vehicle (3) in front of, behind and/or to the side of the contact patch (4) in the direction of travel (F) of the vehicle (3) and has at least one resonant frequency, and a curved first absorber membrane (6), which faces the contact patch (4). Substantially the entire first absorber membrane (6) is oriented normal to a sound propagation direction (S) starting from the contact patch (4), and the sound absorption element (5) has a distance from the contact patch (4) which corresponds to a multiple of a half wavelength (λ) associated with the resonant frequency.

Abstract: The invention relates to a tyre having a directional tread, which forms a contact patch AC when running. It comprises a plurality of blocks (21A, 21B) which form a contact surface SC. The surface voids ratio is defined by TES=(AC-SC)/AC. The blocks (21A, 21B) are organized into patterns (26) of blocks of spacing P, which follow one another in the circumferential direction (X), in a pattern comprising at least one sipe. The sipe density is defined by formula (I), where n is the sipe number, lpyi is the projected distance of the sipe i in the axial direction (Y), and W is the width of the tread. Simultaneously, SD is at least equal to 10 mm -1 and at most equal to 70 mm -1 , and TES is at least equal to 0.40 and at most equal to 0.70.

Abstract: A system for powering an electronic device within a tire is provided, the system comprising: a generator; an electrically conductive wheel coated in a non-conductive coating, the wheel including rim lips, wherein one of the rim lips includes a conductive area; the tire including bead portions, sidewalls, shoulders, a tread oriented in a tread region, and an inner surface; a conductive element extending from a bead portion, and in contact with the inner surface; an electronic device within the vehicle tire; and a ground path extending through a thickness of the vehicle tire from the inner surface to an exterior surface in a contact patch of the tread; wherein the generator is electrically connected to the electrically conductive wheel; wherein the electronic device is electrically connected to the conductive element and the ground path; and wherein the conducive element contacts the conductive area.

Abstract: A method for analyzing fluid around a tire that suppresses reduction in the quality of a computational mesh of a fluid analytic model and that suppresses deterioration in precision and failure of calculations regardless of what sort of groove deformations may occur. The method includes: a step (S100) in which a model (M2) in accordance with a tire finite element method is stored in memory (11), the model (M2) being such that a tire is represented by a plurality of elements and nodes, and having grooves (20) formed at a contact patch, and having groove space elements (30) arranged in groove spaces bounded by groove wall surfaces (21) that form the grooves (20); a step (S101) in which the model (M2) is made to simulate rolling pursuant to analytic conditions which include prescribed load, prescribed internal pressure, and prescribed rotational speed, and numeric operations for calculation of the deformation that would occur in accordance with the model due to contact with the road surface are carried out; a step (S102) in which time series data pertaining to displacements of node groups (P1, P2) including all nodes (P1) that constitute an exterior surface of the tire including the grooves thereon, and at least a portion of all nodes (P2) that constitute the groove space elements (30), is acquired from results of arithmetic operations for deformation in accordance with the model; and a step (S103) in which a fluid analytic model in which space around the tire which includes the exterior surface of the tire and the road surface is expressed as a plurality of computational mesh cells is used to perform arithmetic operations for fluid analysis in which arithmetic operations are carried out with respect to a physical quantity of fluid for each of the computational mesh cells as locations of the computational mesh cells are varied in such fashion that the node groups (P1, P2) in the time series data are made to serve as control points.

Abstract: [Technical field] The present invention relates to the structure of a wheel deformation mechanism and a vehicular shock-absorbing device using said mechanism. [Problem] Conventional suspension devices demonstrate little vibration suppression effect on a vehicle equipped with an in-wheel motor and therefore it is not possible to mitigate impacts on a wheel, thus requiring an installation space on the vehicle-body side. In addition, since conventional tires have little ability to absorb the torsion of a contact patch resulting from cornering, the wheel contact patch is subject to friction in the horizontal direction when the vehicle changes direction. [Solution] An expansion-contraction mechanism, which connects two rotors and a band-like tread by means of a movable arm as shown in fig. 1, is installed in a wheel. [Primary use] A wheel is expanded/contracted depending on the difference between the rotational speeds of two rotors, whereby the orientation of a vehicle body is controlled.

Abstract: The present invention discloses tire wear estimation. A tire wear estimator (100), comprises a tire measurement system which is adapted to be mounted in or on an inner surface of the tire. The tire measurement system comprises a sensor (110) adapted for sensing a physical property of the tire, and an acquisition system (120) adapted for sampling a signal of the sensor (110) into memory (122), to acquire a perturbation in the sampled data which is induced by a contact patch of the tire when the sensor (110) is mounted in or on an inner surface of the tire. A sample rate of the acquisition system (120) is high enough such that at least one oscillation, which is indicative of a tread depth of the tire, becomes detectable in the sampled data in and/or around the perturbation.

Abstract: Disclosed is contact patch data acquisition. A sensor system (100) for acquiring a perturbation, induced by a contact patch of a tire, in data generated by a sensor system mounted in the tire. The sensor system (100) comprising at least one sensor (110) adapted for generating the data related to a physical property of the tire, and an acquisition system (120) comprising memory (122). The sensor system (100) is adapted for triggering the acquisition system (120) to acquire the data and for storing it in a buffer in the memory (122), until a predefined delay after the perturbation is recognized,wherein the perturbation is recognized by comparing the stored data with at least one characterizing feature of the perturbation.