Nowadays, automotive industries focused on clean diesel combustion in their combustion processes are investigated for their potential to achieve near zero particulate and NOx (Nitrogen oxides) emissions. Their main disadvantages are increased level of unburned hydrocarbons (HC) and carbon monoxide (CO) emissions, combustion control at high load, power output and limited operating range. The simulation of the air flow, spray and combustion in an internal combustion engine were prepared for a single cylinder of a nine-liter, six cylinder diesel engine. Many times the geometry is complex because moving pistons and valves are involved, which makes it difficult to generate structured mesh. In-cylinder spray-air motion interaction, a Lagrangian multiphase model has been applied in a heavy-duty CI engine under direct injection conditions. A comprehensive model for atomization of liquid sprays under high injection pressures has been employed. Three dimensional CFD calculations of the intake, compression and power strokes have been carried out with different spray angle, spray profile and start of injection. A new combustion model ECFM-3Z (Extended Coherent Flame Model) developed at IFP is used for combustion modeling. Finally, a calculation on an engine configuration with compression, spray injection and combustion in a direct injection Diesel engine is presented. In this study, exhaust emissions, and particularly the emission of NOx, CO and soot derived from premixed combustion are investigated, and the relationship between combustion and emission characteristics are showed. The calculated CFD simulation in different combustion cases was compared. The cases were prepared by changing the parameters: start of injection, spray angle and spray profile. Modeling of combustion proposed in the present study can be outlined as follows. NOx concentration is decreased by combustion of a over lean-mixture modeled by the pre-injection. Most of pre-mixture is combusted by main-injection, and therefore the amount of pre-injection and main-injection come into prominence. The results are greatly in agreement qualitatively with the previous experimental and computational studies in the literature.

An experimental and numerical study is carried out to evaluate the significance of gas leakage for a non-lube optically accessible internal combustion engine and to obtain estimation for the gas flow out of the combustion chamber at each engine cycle and its effect on the in-cylinder component states during optical engine’s operation. Attention is paid to blow-by and circumferential flow through the gaps between the piston rings and the liner. Optical engines are typically operated without lubrication to avoid window fouling and generation of fluorescence by oil particles that interfere with laser diagnostic signals, in view of this circumstance significant blow-by is expected in optical engines due to lack of “wet-seal” on the cylinder walls which permits circumferential flow of gases through the piston ring pack region resulting in increased blow-by. Semi analytical model estimating the mass loss rate is incorporated into zero dimensional thermodynamic IC engine model which simulates in-cylinder processes. Predicted results are compared for leaking and non-leaking engine simulations.

There is a growing interest in the use of thin-wall structures as a means of absorbing the kinetic energy of a moving body. Multi-layered thin-wall structures are more efficient and lighter than thick-wall structures, and show better crashworthiness characteristics. In this task, several concentric aluminum thin wall tubes as energy absorber under axial and oblique loading are studied and optimum combination of these tubes is presented. The weight of the tubes is optimized while crashworthiness of tubes is not compromised. The commercial finite element program LS-DYNA that offers non-linear dynamic simulation capabilities was used in this study.

The research activities described in this paper aim to identify the causes and the typologies of secondary impact injuries to passengers of a railway vehicle during a specific crash event, to understand the measure in which these injuries can be absorbed and to identify possible ways of reducing or eliminating them. The main investigated solution was to restrain passengers to their seats by considering the presence of seat belts. Biomechanical performances of passenger configurations with two-point and three-point seat belts were investigated and compared with those of unrestrained passengers. An anthropomorphic test device representative of medium size people was furnished and experimental tests were worked out in order to obtain effective data regarding the interaction of passengers with seats and seatbelts. By using these experimental data a multi-body numerical model of the sled test was calibrated and validated and restraining configuration performances, which could not be physically tested, were simulated.

Lane keeping assistance systems help the driver in following the lane centerline. While lane keeping assistance systems are available in some mass production vehicles, they have not found widespread use and are not as common as ESP or ACC at the moment. Lane keeping assistance systems still need further development. Previously available systems have to be continuously adapted to newer vehicle models and fully tested after this adaptation. An image processing algorithm for lane detection and tracking, a lane keeping assistance controller design and a real time hardware-in-the-loop (HiL) simulator developed for testing the designed lane keeping assistance system are therefore presented in this paper. The high fidelity, high order, realistic and nonlinear vehicle model in Carmaker HiL runs as software in a real time simulation on a dSpace compact simulator with the DS1005 and DS2210 boards. A PC is used for processing video frames coming from an in-vehicle camera pointed towards the road ahead. Lane detection and tracking computations including fitting of composite Bezier curves to curved lanes are carried out on this PC. In the present setup, the camera used is a virtual camera attached to the virtual vehicle in Carmaker and provides video frames from the Carmaker animation screen. A dSpace microautobox is available for obtaining the lane data from the PC and the Carmaker vehicle data from the dSpace compact simulator and calculating the required steering actions and sending them to the Carmaker vehicle model. The lane keeping controller is designed in the Matlab toolbox COMES using parameter space techniques. The motivation behind this approach is to develop the lane keeping assistance system as much as possible in a laboratory hardware-in-the-loop setting before time consuming, expensive and potentially dangerous road testing. Lane detection, tracking and curved lane fit results, hardware-in-the-loop simulation results of the lane keeping controller with the image processing system are are used to demonstrate the effectiveness of the proposed method.

A nonlinear adaptive sliding mode control for simultaneous vehicle handling and path tracking improvement through the Steer-By-Wire system is presented in this paper. The proposed adaptive sliding mode controller, which is insensitive to system uncertainties, offers an adaptive sliding gain to eliminate the precise determination of the bound of uncertainties. The sliding gain value is calculated using a simple adaptation algorithm which does not require extensive computational load. A driver control model is also presented according to the preview or look-ahead strategy to generate the appropriate steering angles using the vehicle states feedback and the future information about the path to be followed. Moreover, because of the inertia and viscous damping in the steering mechanism and the effects of coulomb friction and self-aligning moment of the front tires, the steering system controller based on the proposed adaptive sliding mode scheme, is designed to control the front steering angle. A complete stability analysis based on the Lyapunov theory is presented in order to guarantee the closed loop stability. Eventually, the simulation results confirm that the proposed adaptive robust controller not only improves the vehicle handling and path tracking performance but also reduces the chattering problem in presence of uncertainties in the tire cornering stiffness and the external disturbance.

Steer by Wire systems remove the need of a mechanical connection between the governing unit (steering wheel) and the actuated element (steered wheel). With respect to traditional steering systems, SbW systems replace complex mechanical and/or hydraulic components with simple mechatronic components that enable programmable steering features, enhancements in cab design, ergonomics and safety, plus advantages in simplified assembly, all at a cost comparable to traditional systems. The objective of this article is to show how the idea of passive SBW system can be translated into an actual device ready for vehicle applications. To fulfill this aim, functional schemes, mechanical and mechatronic structure and some data about obtainable performance are presented.

In this paper, the dynamic behavior of a quarter-car with two degree-of-freedom which consists of sprung mass and unsprung mass is examined. Nonlinearity occurred due to nonlinear hysteretic suspension damper and spring. Vehicle tire is modeled as a nonlinear hardening spring. The disturbance of road assumed to be sinusoid. Frequency response diagram of the model has been obtained. Results show that the dynamic response of the vehicle can be chaotic. Influence of road roughness amplitude on vehicle vibration is investigated and critical amplitude of the road surface profile is found, above which the system can vibrate chaotically. The comparison between the results obtained from the proposed model and those from the single degree-of-freedom quarter-car model shows that the unsprung mass has great influence on the dynamical behavior of the system, which cannot be ignored.

The body of a passenger car roughly constitutes 25–30% of its overall weight. Any reduction in the weight of the car’s body would not only mean less materials and fuel to be consumed, but also less exhaust emissions to be released and less non-biodegradable materials to be dumped or recycled. However, the automotive industry’s desire for an increasing weight reduction of passenger cars is inevitably limited by other design considerations such as mechanical strength, overall stiffness of the body, durability, safety and corrosion resistance. The problem of weight minimization can be expressed in the form of a constrained, multi-objective optimization problem in which the weight of the body and its fatigue life constitute the conflicting cost functions and values of such critical performance parameters as body’s natural frequency forms the constraint set. The above optimization problem poses a challenge to the designer, as the weight, fatigue life and natural frequency of the geometrically complex body cannot be readily evaluated and a comprehensive numerical model, such as a Finite-Elements (FE) one, has to be employed. This numerical model would nonetheless be highly time-consuming, especially considering the need for re-assessing the model dozens, and sometimes hundreds, of times per iteration of the optimization algorithm. To avoid this, we use a neural approximation of the FE model to reduce the time and computational cost. Results of a finite number of FE simulations are used to train the Multi-Layer Perceptron (MLP) neural network which will then be used as the evaluation engine of the optimization algorithm. An efficient computer code based on the improved Non-dominated Sorting Genetic Algorithms (NSGA II) is used to find the Pareto set of distinct solutions. The designer would then be able to choose from a set of non-dominated, feasible solutions based on economical and/or logistics requirements at an early stage of the design process.

This paper presents the design and the simulation test of a Takagi-Sugeno (TS) fuzzy output feedback for yaw motion control. An integrated steering and differential braking controller based on invariant sets, quadratic boundedness theory and a common Lyapunov function has been developed. The TS fuzzy model is able to handle elegantly the nonlinear behavior the vehicle lateral dynamics. The computation of the control law has been achieved using Linear and Bilinear Matrix Inequalities (LMI-BMI) methods. Simulation test shows the controlled car is able to achieve the ISO3888-2 transient maneuver. Some design parameters can be adjusted to handle the tradeoff between safety constraints and comfort specifications.

In this paper, a computational fluid dynamics (CFD) study is carried out in an effort to design and optimize the cabin geometry and its various parts for drag reduction that include the side deflectors, the mirrors and the sun visor. For the validation of computational results, an experimental investigation using a 1/5 scale truck model has been carried out in a wind tunnel. The aerodynamic force as well as the surface-pressure point measurements carried out at selected wind speeds. The flow visualizations using smoke and oil were also performed. With the experimental results, the basic characteristics of flow over the cabin geometry (including the flow separation locations) are compared with the CFD results. The both steady and unsteady CFD simulations are performed. The comparison of steady/unsteady results reveals that the time-averaged unsteady flow characteristics are practically the same as the steady calculations for design purposes. In addition to CFD simulations involving the actual (real) truck cabin geometry, for the optimization of the specific cabin accessories, (e.g., side deflectors and mirrors), a generic truck model is also used for CFD analyses. The optimized side deflector geometry (e.g., the ratio of the air inlet and outlet area), and the optimum form of the mirrors for drag reduction have been realized by numerical investigations.

Recently, with development in the output power and material cost efficiency, the value of thermal and mechanical stress on many engine parts such as piston is increased. On the other hands, the strength of aluminum alloys used for piston manufacturing decreases with temperature. So, for lightweight pistons, the strength reduction should be minimized to maintain the mechanical integrity of the part. This drives piston designers to use strong and lightweight materials that can sustain a harsh thermal environment through improved oil cooling. In addition to modify the power output, piston cooling reduces the carbonization and pre-ignition caused by hot spots on sharp edges of the piston crown. In this study, in order to evaluate the piston cooling functionality and validate the numerical simulation, a test rig is designed and manufactured and it is equipped with glassy piston and cylinder to show the oil contact surface. Using this test rig, flow rate is measured in different oil pressures and temperatures. In addition, heat transfer coefficient for various engine speeds is determined. Also a numerical model has been developed using CFD approach for analysis of piston cooling oil jet and validated with existing experimental results at axisymmetric condition. Finally, oil contact area and heat transfer coefficient are predicted at the bottom of piston for real piston cooling jet conditions.

A novel semi-active control system for suspension systems of passenger car using Magnetorheological (MR) damper is introduced. The suspension system is considered as a massspring model with an eight-degrees-of-freedom, a passive damper and an active damper. The semi-active vibration control is designed to reduce the amplitude of automotive vibration caused by the alteration of road profile. The control mechanism is designed based on the optimal control algorithm, Linear Quadratic Regulator (LQR). In this system, the damping coefficient of the shock absorber changes actively trough inducing magnetic field. It is observed that utilizing the present control algorithm may significantly reduce the vibration response of the passenger car, thus, providing comfortable drive. The new developed suspension system may lead to design and manufacturing of passenger car in which the passenger may not feel the changes in road profile from highly bumpy to smooth profile.

Automotive engine mounts are used to protect engine from road irregularities and to isolate transmission of vibrations created by the engine which have a drastic effect on the noise generated inside the passenger cabin. Most common types of engine mounts are elastomeric and hydraulic mounts, the former having better vibration isolation characteristics whereas the latter displays better shock isolation. Elastomeric mounts are widely used for their low initial cost, while hydraulic mounts with inertia track and decoupler are chosen for their good vibration isolation and shock excitation characteristics. However, hydraulic mounts with inertia track and decoupler are not appropriate for small segment and commercial vehicles due to their high initial cost. In this paper, the effect of the addition of a dry friction damper on the performance of elastomeric automobile engine mounts is investigated. Results showed that addition of dry friction damping to the elastomeric engine mount significantly improves the transmissibility throughout a wide frequency range where the best results are obtained at the resonance frequency.

Residual stresses are one of the key factors affecting fatigue durability of important cast parts such as cylinder head and engine block. In automotive industry, general approach is to incorporate residual stresses into durability analysis by simply superposing the values by means of a fatigue post-processor. Residual stresses elevate or decrease the mean stress value according to whether stress states are tensile or compressive. However, it is thought that uncoupling two analyses may lead to misleading results. Instead, a single analysis should incorporate residual stress and thermo-mechanical analysis steps, one after the other. This is a comparative study for these two approaches and shows that assumption of a virgin material at the beginning of thermo-mechanical analysis is not always valid although two approaches agrees well with each other for moderate loading levels.

In this paper, a control oriented rational tire model is developed and incorporated in a two-track vehicle dynamics model for the prospective design of vehicle dynamics controllers. The tire model proposed in this paper is an enhancement over previous rational models which have taken into account only the peaking and saturation behavior disregarding all other force generation characteristics. Simulation results have been conducted to compare the dynamics of a vehicle model equipped with a Magic Formula tire model, a rational tire model available in the literature and the present rational tire model. It has been observed that the proposed tire model results in vehicle responses that closely follow those obtained with the Magic Formula even for extreme driving scenarios conducted on roads with low adhesion coefficient.

In this paper, performance of passive vibration isolators, namely rotational / linear tuned mass dampers (TMD) and lever type vibration isolators (LVI), are investigated under different configurations for optimal ride comfort. TMDs reduce vibration levels by absorbing the energy of the system, especially around natural frequencies with the help of viscous dampers. Two types of TMDs, rotational and linear, are investigated in this study. Although linear TMDs can be more easily implemented on suspension systems, rotational TMDs show better performance in reducing vibration levels. The reason is that, the inertia effect of rotational TMDs is higher than linear TMDs. In order to obtain better results with TMDs, a study on different possible configurations is conducted. A plate, with very small mass, is added between sprung and unsprung masses without changing the original suspension spring stiffness and damping coefficients and acts as a support for in-series TMD applications. Finally, LVIs are implemented to reduce sprung mass acceleration and more satisfactory results are obtained especially around body bounce frequency.

In this study, the effectiveness of an active engine mount in vibration suppression of a four-cylinder V-shaped engine is evaluated. In this regard, a 6 degree of freedom engine model under inertia and balancing mass forces and torques is considered. At first, the governing equations of motion of engine supported by three rubber mounts are presented. Subsequently, one of the rubber mounts is replaced by an active mount and the effectiveness of active mount, in the presence of sensor noise, in vibration isolation of the engine is investigated. Two robust control algorithms, namely H 2 and H ∞ schemes are employed to provide control input using feedback from accelerations of the engine body in the position of the mounts. Moreover, unstructured uncertainties due to the unmodeled dynamic of the plant, actuator and sensors are considered. Simulation results show that the active mount is more effective than the rubber mount in vibration suppression of the engine.

An integrated controller of active front steering and direct yaw moment is developed in this paper. In upper layer, the corrective steering angle and yaw moment are obtained using sliding mode control. A combined sliding surface is defined in order that the yaw rate and side slip angle of vehicle track the desired values. The corrective yaw moments are applied by electrical motors embedded in rear wheels. The desired value for yaw rate and sideslip angle are obtained from a 4-DOF nonlinear vehicle model. In the lower layer, the active steering, wheel slip and electrical motor torque controllers are designed. Wheel slip and motors torque controllers generate the longitudinal forces in the rear wheels to produce the desired yaw moment. A nonlinear nine degrees of freedom vehicle model is used for simulation purposes. The simulation results illustrate considerable improvements in vehicle handling.

Engine mount vibration level, which is mainly driven by gas and unbalanced inertial forces, is one of the key metrics for the NVH (Noise Vibration Harshness) performance of a vehicle. In addition to gas and unbalanced inertial forces, crankshaft dynamics has also effect on engine mount vibrations. This project is concentrating in including the effect of crankshaft dynamics on engine mount vibrations with the aid of Finite Element Methods and Multi Body Dynamics. Flywheel swirl mode, its effect on engine mount vibration levels and engine mount acceleration for different flywheel configurations will be simulated.