Research into truck transmission torsion vibrations under longitudinal acceleration

The development of a modern motor vehicle is aimed at improving the performance in the field of dynamics (both longitudinal and lateral), economy, safety and ergonomic characteristics. Special attention is paid to passenger comfort. Torsional oscillations in transmission cause longitudinal vibrations of the vehicle, depending on inertial parameters, as well as on stiffness and damping of the transmission. Taking into account the complexity of the problem, it is estimated that it is useful to analyse the impact of the transmission design parameters on the longitudinal (fore and aft) vibrations of freight motor vehicle. For this purpose, the dynamic simulation method was used, and the analysis of the influence of certain constructive parameters on the longitudinal oscillations of the vehicle was performed using the sensitivity function

Jedan postupak za izbor bočnih karakteristika pneumatika sa aspekta minimalnog vijuganja prikolice putničkog motornog vozila

In the initial phase of motor vehicles design, and therefore their trailers, the dimensions and type of tires are adopted according to the required payload, from the manufacturer's catalogue. The fine-tuning of the characteristics, especially the lateral characteristics of the tires, is carried out in the later stages of design, using models or experimental methods. The yaw of the trailer, as part of the passenger vehicle-trailer system, using its simple dynamic model, is analysed in this paper. The equations of motion were derived using the Newton's laws for constant longitudinal velocity of a vehicle. Tires are described by models based on higher degree polynomial approximation. Optimal selection of the corresponding parameters of the lateral characteristics of the tires was made using the Hooke-Jevees method. Constructive parameter constraints have been introduced by the use of external penalty functions. The optimization process of minimizing the trailer's yaw angle was started with three sets of initial values of the optimizing parameters. Analyses have shown that it is sufficient to start with the midpoint of the parameter definition interval and the obtained data enable a quick selection of the lateral characteristics of the trailer's tires at the conceptual stage of its design.Publishe

Research into truck transmission torsion vibrations under longitudinal acceleration

The development of a modern motor vehicle is aimed at improving the performance in the field of dynamics (both longitudinal and lateral), economy, safety and ergonomic characteristics. Special attention is paid to passenger comfort. Torsional oscillations in transmission cause longitudinal vibrations of the vehicle, depending on inertial parameters, as well as on stiffness and damping of the transmission. Taking into account the complexity of the problem, it is estimated that it is useful to analyse the impact of the transmission design parameters on the longitudinal (fore and aft) vibrations of freight motor vehicle. For this purpose, the dynamic simulation method was used, and the analysis of the influence of certain constructive parameters on the longitudinal oscillations of the vehicle was performed using the sensitivity function

Numerical Simulation of Shock Absorbers Heat Load for Semi-Active Vehicle Suspension System

Dynamic simulation, based on modelling, has a signtficant role during to the process of vehicle development. It is especially important in the first design stages, when relevant parameters are to be defined. Shock absorber, as an executive part of a semi-active suspension system, is exposed to thermal loads which can lead to its damage and degradation of characteristics. Therefore, this paper attempts to analyse a conversion of mechanical work into heat energy by use of a method of dynamic simulation. The issue of heat dissipation from the shock absorber has not been taken into consideration

Contribution to the investigation of the influence of tire non-uniformity on the lateral tire characteristics

Tire models are widely used in research in the field of vehicle dynamics and noise, and especially in the simulation of their movement under the action of forces and moments. In general case, we distinguish theoretical models defined on the basis of tire construction and empirical or semi-empirical models based on experimental tests. In addition, a combination of these two types of models can also produce tire models. In practice, there is a very wide range of mathematical tire models defined using finite element analysis, by approximation of polynomials of different degrees, by approximation of magic formula, etc. In this paper, an attempt is made to calculate non-stationary lateral characteristics of tires on the basis of experimental stationary lateral characteristics, using two-parameter higher level polynomials. This polynomials define the tire lateral characteristics, and take into account their non-uniformity. More specifically, the lateral characteristics are approximated as a function of the dynamic change of the slip angle, radial load due to tire non-uniformity and time

A contribution to the study of thermal loads of hydraulic and active mounts of powertrain of a freight motor vehicle

Due to the excitation from the road micro unevenness, powertrain vibration and conditions of motion (acceleration, braking, curved motion) trucks masses make complex spatial oscillatory movements. The negative impact of these movements, i.e. dynamic loads arising from those movements and transferred to the vehicle chassis, can be reduced by the proper choice of the position and characteristics of the powertrain mounts. The elastodamping forces in the mounts perform mechanical work which is converted into a thermal energy. Theoretical, experimental and combined methods can be used to analyse thermal loads of mounts. In this paper, research was carried out using theoretical methods using the simplified mechanical model of the powertrain. The vibrations of the powertrain of a trucks manufactured by FAP were observed. Thermal load analysis was performed for hydraulic and active mounts

Contribution to identification of mechanical characteristics of passenger motor vehicle’s drum brakes

Na temelju provedenih analiza, dokazano je da ne postoji opće prihvaćena metoda ocjene karakteristika i izlaznih parametara mehanizama bubanj kočnica. U radu su prikazana eksperimentalna istraživanja podsustava bubanj kočnica s ulaznom vrijednosti-tlakom kočione tekućine u cilindru kočnice i izlaznom vrijednosti-kočnim momentom. Dobiveni rezultati su pokazali da je između izlaza i ulaza postojalo vrijeme kašnjenja, zbog odgovora mehanizma bubanj kočnice. To ukazuje na nedostatak utvrđivanja performansi kočnica u vremenskoj domeni, jer u usporedbi nisu adekvatna uzbuda i odgovor sustava. Stoga se u analizi podsustava bubanj kočnice promatra dinamički mod. Dinamička analiza određuje ponašanje sustava u prijelaznom razdoblju. Uz već poznate prijenosne karakteristike sustava, njegov odgovor može biti određen u odnosu na navedene ulaze, uzbude, što je dobar temelj za određivanje korelacija između rezultata dobivenih različitim metodama identifikacije i pod različitim uvjetima ispitivanja.Based on the conducted analyses, it has been proven that there is no generally accepted method for evaluation of characteristics and output parameters of drum brake mechanisms. Experimental research of the drum brake subsystem with brake fluid pressure in the brake cylinder as input quantity and brake torque as output quantity is presented in the paper. The obtained results show that there is a time delay between the output and input due to the response of the drum brake mechanism. This points to the deficiency of determination of brake performance in time domain, because, in comparison, excitation and response of the system are not adequate. Hence, the dynamic mode is observed in the analysis of the drum brake subsystem. Dynamic analysis determines the behaviour of the system in transient period. With previously known transfer characteristics of a system, its response can be determined in relation to the specified inputs (excitations), which is a good basis for determination of correlation between the results obtained by different methods of identification and under different test conditions

Contribution to identification of mechanical characteristics of passenger motor vehicle’s drum brakes

Na temelju provedenih analiza, dokazano je da ne postoji opće prihvaćena metoda ocjene karakteristika i izlaznih parametara mehanizama bubanj kočnica. U radu su prikazana eksperimentalna istraživanja podsustava bubanj kočnica s ulaznom vrijednosti-tlakom kočione tekućine u cilindru kočnice i izlaznom vrijednosti-kočnim momentom. Dobiveni rezultati su pokazali da je između izlaza i ulaza postojalo vrijeme kašnjenja, zbog odgovora mehanizma bubanj kočnice. To ukazuje na nedostatak utvrđivanja performansi kočnica u vremenskoj domeni, jer u usporedbi nisu adekvatna uzbuda i odgovor sustava. Stoga se u analizi podsustava bubanj kočnice promatra dinamički mod. Dinamička analiza određuje ponašanje sustava u prijelaznom razdoblju. Uz već poznate prijenosne karakteristike sustava, njegov odgovor može biti određen u odnosu na navedene ulaze, uzbude, što je dobar temelj za određivanje korelacija između rezultata dobivenih različitim metodama identifikacije i pod različitim uvjetima ispitivanja.Based on the conducted analyses, it has been proven that there is no generally accepted method for evaluation of characteristics and output parameters of drum brake mechanisms. Experimental research of the drum brake subsystem with brake fluid pressure in the brake cylinder as input quantity and brake torque as output quantity is presented in the paper. The obtained results show that there is a time delay between the output and input due to the response of the drum brake mechanism. This points to the deficiency of determination of brake performance in time domain, because, in comparison, excitation and response of the system are not adequate. Hence, the dynamic mode is observed in the analysis of the drum brake subsystem. Dynamic analysis determines the behaviour of the system in transient period. With previously known transfer characteristics of a system, its response can be determined in relation to the specified inputs (excitations), which is a good basis for determination of correlation between the results obtained by different methods of identification and under different test conditions

Contribution to the research of oscillatory loads of sprung and unsprung masses in order to create conditions for laboratory tests of heavy motor vehicles

Introduction/purpose: Motor vehicles are complex dynamic systems due to spatial displacements, changes in the characteristics of components during their lifetime, a large number of influences and disturbances, the appearance of backlash, friction, hysteresis, etc. The aforementioned dynamic phenomena, especially vibrations, cause driver and passenger fatigue, reduce the lifetime of the vehicle and its systems, etc. Methods: In general, the movement of vehicles is carried out on uneven roads and curvilinear paths in the road. Not only do oscillatory movements cause material fatigue of vehicle parts, but they also have a negative effect on people's health. That is why special attention must be paid to the coordination of the mutual movement of the subsystems, and in particular, the vehicle suspension system, even at the stage of the motor vehicle design. For these purposes, theoretical, experimental or combined methods can be used. Therefore, it is very useful to have the experimental results of the oscillations of the vehicle subsystem in operating conditions, so the aim of this work was to use the movement of the 4x4 drive FAP 1118 vehicle in operating conditions (due to higher speeds - in road conditions) to define the conditions for testing oscillatory loads in laboratory conditions. Results:This is made possible by registering and identifying statistical parameters of registered quantities. Conclusion: Based on the measured data, the research can be programmed on shakers in laboratory conditions, and, at the same time, the size to be reproduced can be chosen as well

Razvoj modela vozača za upravljanje vozilom tokom pravolinijskog kretanja / Development of driver model for vehicle control during a straight line motion

Upravljanje vozilom na pravolinijskom putu spada u specijalan slučaj analize dinamičkog sistema vozač - vozilo - okruženje, jer podužno kretanje vozila podrazumeva aktivno učešće vozača u uslovima koji su definisani parametrima puta i vozila. U savremenoj literaturi postoje pokušaji modeliranja pomenutog sistema u uslovima pravolinijskog kretanja, ali, do sada, nije definisan opšteprihvaćeni model vozača. Problem se usložava činjenicom da se u razmatranje mora uzeti i veoma složeno ponašanje motora i transmisije u dinamičkim uslovima. U radu je modeliran sistem vozač - vozilo u uslovima pravolinijskog kretanja radi praćenja zadate, najčešće, promenljive brzine vozila. / To drive the vehicle on a straight line road can be put as a special case analysis of a Driver-Vehicle-Environment dynamical system, because longitudinal vehicle motion means that active driver participates in the conditions defined by road and vehicle parameters. In contemporary literature, there are some attempts of modeling the mentioned system in the case of a straight line drive, but, so far, there is no generally accepted model of a driver. It should be mentioned that the problem is more complex with fact that a very complex motor and transmission behavior must be assumed in dynamic conditions. There are some attempts of modeling the driver and vehicle in the case of straight line driving, with a goal of tracking the given, frequently variable vehicle speed