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Conventional journal bearing has been used in automotive engine crankshaft satisfactorily, however, the significant contribution of such bearing in the overall power losses cannot be ignored. In the present study, a comparison has held between the frictional behaviour of the conventional and floating-ring bearings under transient loading conditions. The governing equations of the two dynamically loaded fluid films in the main and connecting rod big-end floating-ring bearings have solved numerically using convenient boundary conditions. The Tribological performance of such design has compared with that of conventional journal bearing under the same operating conditions. Results have shown that, frictional losses in floating-ring bearing are lower than that of conventional journal bearing which in turn improves the engine mechanical efficiency and reduces the breakdowns and maintenance cost.

In this paper, the effect of the dynamic interaction between tractor and semitrailer on the ride behaviour of heavy good vehicles is investigated. A multi-body model is constructed for a 4-axle tractor-semitrailer vehicle with flexible frames and excited by random road irregularities. The modal parameters of the connected frames are calculated using the FEM (Finite Element Method), as an integrated free vibrating structure, and incorporated with the equations of motion of the whole vehicle which are generated using the Lagrange energy approach. Frequency response analysis is carried out for random road excitations to evaluate the vehicle ride dynamics. In order to give a broad overview of the vehicle ride quality, different loading conditions are considered in the computer simulation. The results showed that the acceleration levels of vehicle components are significantly increased when the effect of an empty semitrailer is considered within the vehicle model.

In this paper, a hybrid roll control system, including passive and active roll control units, is designed to improve the roll dynamics of tanker vehicles and to reduce the lateral shifts of the liquid cargo due to lateral accelerations. The passive control system consists of radial partitions installed inside the vehicle container. These partitions rotate in phase with the liquid cargo as one unit about the longitudinal axis of the container in response to the induced momentum forces due to the lateral acceleration excitation. Torsion dampers are fixed between the partitions and the container's front and rear walls to reduce the oscillating motion of the liquid cargo. While the passive partition dampers control the dynamics of the liquid cargo inside the container, the dampers of the vehicle suspension are switchable, generating anti-roll damping moments based on the lateral acceleration level and the container filling ratio.

In this paper, a direct technique to estimate the rollover threshold limits of partially filled tank trucks is applied for banked roadways. Overturning and restoring moments are calculated as functions of tank shape, fill level, gradient of both liquid cargo free surface and the lateral inclination of banked road surfaces. The static rollover threshold of tanker trucks traveling on laterally banked roadways is estimated by balancing the net value of the total overturning moment against the net value of the restoring moment. Different filling ratios are considered for circular, elliptical and modified tank vehicles. The rollover threshold limits are calculated considering a superelevation range of (0.0-0.1) for the lateral road banking as defined by Blue and Kulakowski (1991). It is shown that the vehicle rollover threshold limit increases with an increase of the angle of the lateral road banking.

The present paper presents design considerations for a new tandem suspension system equipped with hydro-pneumatic components. The theory of the new suspension and its configuration were presented in a previously published SAE paper, [1]. In this design, most of the vertical motions were transformed into horizontal motions through two bell cranks. A hydraulic actuator is installed horizontally between the bell cranks and connected to an accumulator (gas spring) via a flow constriction (damper). Incorporating of hydro-pneumatic components in the new suspension system exhibits simple and applicable design. Moreover, further developments including active or semi-active vibration control systems, can be applied directly using the existing hydro-pneumatic components. Mathematical models are constructed to simulate the vehicle ride dynamics. Equations of motion are generated considering a conventional passive suspension (four springs tandem suspension) and the new designed suspension system.

This work describes a 3 dimensional modeling technique for investigating the random response of tractor semitrailer systems considering different types of fifth wheels and their kinematic constraints. The inputs to the vehicle model are the power spectral density (PSD) of the vertical road irregularities considering different road types. In addition to the time delay axle correlation, the cross correlation between the left and right tracks is modeled using the coherence function. The masses of the driver/seat assembly, tractor, semi-trailer and wheel/axle assemblies as well as their suspension elements are considered in the vehicle model. The possibility of reducing the roll accelerations of both tractor and semi-trailer by using a compensating fifth wheel (articulation) has been studied. The designed fifth wheel is a fully oscillating unit. Using this fifth wheel, the tractor and semi-trailer could oscillate relatively in the pitch and roll directions.

In this paper, a non-linear simulation analysis for a 4 axles tractor semitrailer vehicle is addressed using a 14 degrees-of-freedom ride model that includes the structural dynamics of both tractor and semitrailer frames. The system non-linearity is arising due to the inclusion of switchable dampers in the vehicle cab suspension systems. The modal properties of the articulated vehicle frames are calculated using the FEM (finite element method) and then incorporated with the rigid parameters and motions of the different components of the vehicle system. The equations of motion are derived taking into account the interaction between both tractor and semitrailer frames. The Runge-Kutta method has been used to solve the non-linear differential equations of motion of the vehicle system in the time domain. Random signals are used to simulate the road surface irregularities and to excite the components of the vehicle system with low and high roughness levels (smooth and rough roads).

It is well known that the excessive levels of vibration in heavy vehicles negatively affect driver comfortability, cargo safety and road condition. The current challenge in the field of suspension design for heavy vehicles is to optimize the suspension dynamic parameters to improve such requirements. Almost all of the previous work in this field is based on applying the mathematical optimization considering active or passive suspension systems to obtain the optimal dynamic parameters. In this work a new passive suspension systems for heavy trucks is suggested and compared with the conventional passive suspension systems. The new systems rely on transferring the vertical motion, (vibration), into horizontal motion through a bell-crank mechanism to be taken by a horizontal passive suspension system. The system dynamic parameters like body acceleration, suspension travel and dynamic tire load are calculated assuming random excitation due to road irregularities.

The slosh forces arising due to liquid motion in partially filled containers affect the roll dynamic stability of tank vehicles. In this paper, a simplified dynamic truck roll model has been developed considering both suspension flexibility and nonlinear dynamics of the liquid cargo motion. A small-scale experimental model for a cylindrical truck tank, excited in the lateral direction, is designed and constructed to measure the viscous damping and damped natural frequency of the liquid cargo. Since the viscous damping of the liquids is limited by its natural characteristics, partitions containing rectangular slots and holes of different sizes are used to generate additional damping. It is fitted against the lateral motion of the liquid slosh, i.e. parallel to and passing through the longitudinal axis of the vehicle. These types of partitions increase the motion damping of the liquid cargo and make the liquid behave like a dynamic absorber.

Recently, the application of active suspension systems in commercial vehicles is recommended to reduce road damages due to the generated dynamic tyre loads and to improve ride quality, structure safety and both handling and traction stability. The purpose of this paper is to design suspension controllers for a tractor semi-trailer system considering chassis elasticity and the controller time delay. The modal parameters of the vehicle chassis as a separate free-free substructure (connected tractor and semitrailer frames) are calculated using the finite element method and then incorporated with the rigid parameters and motions of the whole vehicle components. The connection (articulation) between the tractor and semitrailer frames is modeled by a vertical spring with its ends attached to the tractor and semitrailer frames.

Eliminating high frequency vibrations during braking is an important task for both vehicle passenger comfort and reducing the overall environmental noise levels. Modeling of the disc brake assembly to take account of the effect of different geometrical and contact parameters on its stability is studied through the use of seven degrees of freedom multi-body model. Linear simulation technique is used to define the system stability. In this study, time domain response of the brake assembly is calculated and the vibration modes of the pad, disc, piston and caliper are identified through the used simulation technique. The effect of some geometrical and contact parameters on the stability of the system have been studied. The selection of the position of load application by the piston is found to have substantial importance. An optimum piston position has been suggested in this work at which, minimum vibration levels have been achieved.