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.

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The work describes model and experimental tests on the road restraint systems with particular attention to vehicle collisions with a concrete protective barrier. Vehicle and protective barrier crash tests include the experiment results in three basic fields: intensity of influence of the collision effects on vehicle passengers, collision impact on a vehicle and the road restraint system. It presents a test track concept as well as criteria for performing and evaluating the crash tests with a passenger vehicle and a safety barrier. The experimental tests were performed according to the test methodology recommended by the standard [2]. Examples of model test results were compared with experimental test results obtained on the test track.

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This article presents a simulation study of the suspension system in a vehicle that weighs approximately 12 tons (class N2). The authors have tested the influence of experimentally determined values of friction coefficients on the energy dissipated in the multi-leaf spring. The study was carried out using finite element analysis with LS-DYNA software. A nonlinear vibration model of the complete spring was developed, including the variable friction forces between the leafs. The model takes into account the sprung and unsprung mass of the chassis. Numerical tests were carried out using three different coefficients of friction (determined experimentally) for a selected speed of the car. Random realizations of the road micro-profile (type A, B, C) recommended by ISO 8608 were used. The results of the tests were presented in the form of acceleration curves in the vertical direction, comparative plots of daily vibration exposure A(8) and vibration transmission coefficient (T), and the distributions of RMS acceleration in frequency of one-third octave bands. This data was used to assess the quality of the vibration isolation system between the front suspension of the vehicle and the driver’s seat.

This paper presents the results of experimental investigations of the effects of car wheel unbalance on driving safety and comfort. Basic information about types of wheel unbalance, their causes, and effects are included. The test subject was a BMW 3 Series car with rear-wheel drive. A specific unbalance was introduced on the front steered wheels. The vehicle was driven in a straight line on an asphalt road in good condition at speeds between 70 km/h and 140 km/h. During the test runs, acceleration waveforms were recorded from sensors placed on the lower control arm, driver's seat, and steering wheel. The vibration level of the unbalanced wheel increases with the driving speed and with the increase in unbalance. The highest increase in vibration amplitude occurred on the steering wheel at speeds between 100 km/h and 120 km/h. These vibrations have a direct effect on the driver. This is evidenced by negative driver perceptions such as fatigue and driving discomfort. This was also confirmed by the calculated vibration exposure levels. Driving with unbalanced wheels accelerates wear on the tyres, steering, drive, and suspension components of the vehicle.

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