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This study presents a practical theoretical method to judge the aerodynamic response of buses in the early design stage based on both aerodynamic and design parameters. A constant longitudinal velocity 2-DOF vehicle lateral dynamics model is used to investigate the lateral response of a bus under nine different wind gusts excitations. An appropriate 3-D CFD simulation model of the bus shape results is integrated with carefully chosen design parameters data of a real bus chassis and body to obtain vehicle lateral dynamic response to the prescribed excitations. Vehicle model validity is carried out then, the 2-DOF vehicle lateral dynamics model has been executed in MATLAB Simulink environment with the selected data. Simulation represents the vehicle in a straight ahead path then entered a gusting wind section of the track with a fixed steering wheel. Vehicle response includes lateral deviation (LD), lateral acceleration (LA), yaw angle (YA) and yaw rate (YR).

The minimum support stiffness that achieves the maximum modal frequencies or critical speed is very important in the design of mechanical systems. The optimal values of the intermediate support stiffness and geometrical parameters of uniform and stepped Timoshenko beams composed of single or two materials are studied in order to maximize the modal frequency and minimize the intermediate support stiffness. Dynamic stiffness matrix (DSM) method and multi-objective particle swarm optimization (MOPSO) algorithm are used together to evaluate new optimal parameters. For single material, the results show that for uniform thick beams, the optimal maximum fundamental frequency and minimum intermediate support stiffness are lower than those of Bernoulli-Euler beams. In addition, the optimal design for stepped beams made of two metallic materials is investigated. For three different metallic combinations, gain factors of 1.561 to 2.745 are obtained for a beam without intermediate support.

Vehicle Handling performance depends on many parameters. One of the most important parameters is the dynamic behavior of the steering system. However, steering system had been enhanced thoroughly over the past decade where Active Front Steering (AFS) is now present and other system as Active Independent Front Steering (AIFS) is currently in the research phase. Actually, AFS system adopt the front wheels’ angles base on the actual input steering angle from the driver according to vehicle handling dynamics performance. While, the AIFS controls the angle of each front wheel individually to avoid reaching the saturation limits of any of the front wheels’ adhesion. In this paper modeling and analysis of an AIFS is presented with Tire Work Load (TWL) based controller. Magic Formula tire model is implemented to represent the tire in lateral slip condition.

In this paper, a nonlinear semi-active vehicle suspension system using MR fluid dampers is investigated to enhance ride comfort and vehicle stability. Fuzzy logic and fuzzy self-tuning PID control techniques are applied as system controllers to compute desired front and rear damping forces in conjunction with a Signum function method damper controller to assess force track-ability of system controllers. The suggested fuzzy self-tuning PID operates fuzzy system as a PID gains tuner to mitigate the vehicle vibration levels and achieve excellent performance related to ride comfort and vehicle stability. The equations of motion of four-degrees-of-freedom semi-active half-vehicle suspension system incorporating MR dampers are derived and simulated using Matlab/Simulink software.

Nonparametric models do not require any assumptions on the underlying input/output relationship of the system being modeled so that they are highly useful for studying and modeling the nonlinear behaviour of Magnetorheological (MR) fluid dampers. However, the application of these models in semi-active suspension is very rare and most theoretical works available on this topic address the application of parametric models (e.g. Modified Bouc-Wen model). In this paper, a nonparametric MR damper model based on the Restoring Force Surface technique is applied in vehicle semi-active suspension system. It consists of a three dimensional interpolation using Chebyshev orthogonal polynomial functions to simulate the MR damper force as a function of the displacement, velocity and input voltage. Also, a damper controller based on a Signum function method is proposed, for the first time, for use in conjunction with the system controller of a semi-active vehicle suspension.

The dynamics of vehicles became one of the most important aspects for current developments of electronically controlled steering, suspension and traction/braking systems. However, most of the published research on vehicle maneuverability doesn't take into account the effect of the dynamic tire load and its variation on uneven roads. Clearly, it was stated that using a suitable active suspension system could reduce this dynamic tire load. This dynamic tire load is playing a vital role as it is the major link between the vertical and lateral forces exerted on the road, which affects the lateral dynamics of the vehicle. In this paper, a practical hydro-pneumatic limited bandwidth active suspension system with and without wheelbase preview control is used to study its influence on the vehicle stability in lateral direction. The model is a longitudinal half car with four degrees of freedom.

The transformation of rapeseed oil into methyl ester through the transestrification process normally produce biodiesel fuel with kinematic viscosity almost double that of the commercial diesel fuel. The bulk modulus of biodiesel is also higher than that for the conventional diesel fuel. In this paper, the effects of the two physical properties on the injection characteristics of Rapeseed Methyl Ester (RME) are discussed. The injection characteristics considered here were namely; nozzle chamber pressure, needle lift, and fuel injection rate. The mutual effects of engine speed and delivery pipe length were also analyzed. A previously developed computer model was used to simulate the injection process of the conventional pump-line-nozzle injection system. An explicit finite difference scheme was adopted to solve the unsteady flow equation within the delivery pipe.

In this work the effects of vehicle vertical vibrations on the tires/road cornering forces, and then consequently on vehicle lateral dynamics are studied. This is achieved through a ride model and a handling model linked together by a non-linear tire model. The ride model is a half vehicle with four degrees of freedom (bounce and pitch motions for vehicle body and two bounce motions for the two axles). The front and rear suspension are a hydro-pneumatic slow-active systems with 6 Hz cut-off frequency designed based on linear optimal control theory. Vehicle lateral dynamics is modeled as two degrees (yaw and lateral motions) incorporating a driver model. An optimal rear wheel steering control in addition to the front steering is considered in the vehicle model to represent a Four Wheel Steering (4WS) system. The tire non-linearity is represented by the Magic Formula tire model.

Vehicle suspension along with tires and steering linkages is designed for safe vehicle control and to be free of irritating vibrations. Therefore the suspension system designs are a compromise between ride softness and handing ability. However, this work is concerned with a theoretical investigation into the ride behavior of actively suspended vehicles. It is based on using fuzzy logic control (FLC) to implement a new sort of active suspension system. Comparisons between the behavior of active suspension system with FLC with those obtained from active systems with linear control theory (LQR), ideal skyhook system and the conventional passive suspension systems. Results are introduced in such a way to predict the benefits that could be achieved from fuzzy logic system over other competing systems. Furthermore, a controller is designed and made by using results of FLC system, theoretical inputs are used to examine the validity of this controller.

The number of speed humps (sleeping policemen) has seen a global increase in the last decade. This paper addresses the geometric requirements of these humps using Genetic Algorithms optimization techniques to control the speed, stability, and ride feel of the traversing vehicles. The interaction between road hump profile and the modeled vehicles (passenger and a two-axle truck) are studied with a dynamic model. The shape of the proposed profile is described by numbers of amplitudes of harmonic functions. The extreme acceleration of the drivers’ seats of the vehicles traversing the hump is set as multiobjective function for the optimization process, taking into consideration the road-holding ability represented by the tire lift-off speed. The results show that hump geometry can be improved while fulfilling the requirements of speed control and vehicle dynamic responses.

Dynamic modeling of the gear vibration is a useful tool to study the vibration response of a geared system under various gear parameters and operating conditions. An improved understanding of vibration signal is required for early detection of incipient gear failure to achieve high reliability. However, the aim of this work is to make use of a 6-degree-of-freedom gear dynamic model including localized tooth defect for early detection of gear failure. The model consists of a gear pair, two shafts, two inertias representing load and prime mover and bearings. The model incorporates the effects of time-varying mesh stiffness and damping, backlash, excitation due to gear errors and modifications. The results indicate that the simulated signal shows that as the defect size increases the amplitude of the acceleration signal increases. The crest factor and kurtosis values of the simulated signal increase as the fault increases.

The early detection of incipient failure in a mechanical system is of great practical importance as it permits scheduled inspections without costly shutdowns and indicates the urgency and locations for repair before a system incurs catastrophic failure. However, in this work a new technique for processing vibration data to quantify the level of damage, cracks only, in a gear system. The technique consists of a nonlinear numerical optimization. The optimization uses a dynamic model of the gear mesh used in vehicle gearbox and forms an estimate of both time-varying and frequency-varying mesh stiffness that best corresponds to the given set of vibration data. The procedure developed in this study can be applied as a part of either an onboard machine health monitoring system or a health diagnostic system used in the regular maintenance.

During the last few decades, fibrous composite materials have been diversified and replaced some traditional metallic materials. These materials provide high strength to weight ratio together with high environmental corrosion resistance. One of the basic engineering applications, which have been attracted by the properties of these composites, is the automotive engineering. In this paper, the authors manipulated the composite C-compression springs as a new trend of vehicle suspension system instead of coil or leaf springs. This type of springs can be safely and efficiently implemented in the vehicles' suspension systems and most probably be used in the new suspension design proposed earlier by one of the authors. Previous work on this context had shown a quality nature and economical technology in the use of composite springs in transportation and/or industrial applications.

The study of the combustion process in a novel internal combustion engine is presented. The novel engine is part of an electric power generator and has been designed to work at low average combustion temperatures to achieve very low NOx emissions. The engine is two-stroke, with one cylinder and two pistons in-line. The combustion occurs in two combustion pre-chambers for each piston. Charge stratification leading to stoichiometric mixture inside the pre-chamber and cold air in the rest of the cylinder is adopted. Progressive burning of the charge is expected to keep the flame inside the pre-chamber with the combustion products ejected very fast and effectively mixed with the cold air in the cylinder. The study has been performed with the help of Computational Fluid Dynamics. For the preliminary engine design, the main characteristics of the combustion process have been analyzed.

This paper is concerned with the analysis of the performance of actively suspended vehicles when the effects of the aerodynamics are considered. The investigation is wholly theoretical and treats a half vehicle model, active suspension, through simulation of running at different speeds on a random-profile road. Using classical control laws, which do not account for aerodynamic effects, it is shown that starting from a vehicle speed of 35 m/s, ride comfort and road holding parameters significantly deteriorate. A method is introduced to modify the control strategy so that these effects can be taken into consideration. Various forms of control laws are presented, and conclusions are drawn to specify the benefits that could be achieved from this modified control strategy.

E-spring is a recent innovation in vehicle suspension springs. Its behavior and characteristics are investigated experimentally and verified numerically. The mechanical and frequency-response-based properties of E-springs are investigated experimentally at both of the structural and constitutional levels. Thermoplastic-based and thermoset-based fibrous composite structures of the E-springs are modified at micro-scale with various additives and consequently they are compared. The experimental results reveal that additives of micrometer-sized particles of mineral clay to an ISO-phthalic polyester resin of the composite E-spring can demonstrate distinguished characteristics. A hybrid approach of the inter-laminar shear stress and Tsai-Wu criteria is implemented in order to identify failure indices numerically at the utmost level of loading and verify the experimental results.

Many basic studies were conducted to discover the main reason for squeal occurrence in both disc and drum brake systems. As, it is well-known that the squealed brake system is more effective than the non-squealed brake system and it is also a common discomfort. So, cancellation of the squeal is not preferable, however, elimination of the brake squeal is a favorable. An approach to study the drum brake squeal is presented based mainly on the Finite Element Method (FEM) representation. The brake system model is based also on the model information extracted from finite element models for individual brake components. This finite element method (FEM) was used to predict the mode shape and natural frequency of the brake system after appropriate verification of FEM.

A non-contact analysis of a drum brake based on three-dimensional Finite Element analysis using Ansys is presented. The effect of drum-lining interface stiffness and line pressure on the interface contact is examined. The modal analysis of the vehicle drum brake is also studied to get the natural frequency and instability of the drum. It is shown that the unsymmetric modal analysis is efficient enough to solve this linear problem after transforming the non-linear behaviour of the contact between the drum and the lining to a linear behavior. A linear element which is used in the modal analysis is transferred to non-linear elements which are Targe170 and Conta173 that represent the drum and lining to study the contact analysis. The contact analysis problems are highly non-linear and require significant computer resources to solve it, however, the contact problem give two significant difficulties.

A full vehicle of a preview control semi-active suspension system based on an interval type-2 fuzzy controller design using a magnetorheological (MR) damper to improve ride comfort is investigated in this paper. It is integrated with the force distribution system to obtain the optimal rate of road adhesion during braking and handling. The nonlinear suspension model is derived by considering vertical, pitch, and roll motions. The preview interval type-2 fuzzy technique is designed as a system controller, and it is attached with a Signum function method as a damper controller to turn on the voltage for the MR damper. This voltage is adjusted for each wheel based on the external excitation generated by road roughness in order to enhance ride comfort. To describe the effectiveness and adaptable responses of the preview controlled semi-active system, the performance is compared with both the passive and MR passive suspension systems during time and frequency domains.

The previous research work on Active Independent Front Steering (AIFS) system concluded an enhanced vehicle response and tire adhesion utilization. Some research emphasizes the importance of Tire Work load (TWL) in the generation of maximum possible tire forces that ensures vehicle controllability and stability. In this study, a mathematical model is constructed to investigate the effect of TWL as a parameter on AIFS performance. Toward such a target, a new Fuzzy control strategy is developed based on TWL and vehicle yaw rate as control inputs for the AIFS controller. Unfortunately, the TWL is not a measurable parameter or even easy to be estimated. Consequently, another control strategy was implemented based on slip angle and vehicle yaw rate as inputs for the AIFS controller.