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Technical Paper

Vehicle Braking System Calculation and Simulation Software Platform

The brake performance is one of the most important performances in the automotive active safety, and it is the main measure of automotive active safety. Thus, to develop a platform for the braking system is quite significant. Based on the object-oriented technology, the platform for braking system is developed by making use of Visual C++ 6.0 development tool. By using the VC++ development tool and doing secondary development on other softwares, the software possesses powerful features, such as brake plan selection, performance calculation, parametric modeling, finite element analysis and kinematics simulation, etc. An initial brake system can be designed, calculated and analyzed all in one. The living instance shows that the platform has friendly user interfaces, powerful functions and it can improve the precision and efficiency of brake design. The platform has been of great applied value and can also positively promote the design automation of vehicle's braking system.
Technical Paper

Nonlinear System Identification of Road Simulation Platform

On road simulation, both the traditional iterative method based on frequency response function (FRF) and adaptive control method based on the CARMA model are realized by using linear model to identify the target test system. However the real test system is very complicated because of various nonlinear factors. Linear models approximately describe the system only in a small range. Therefore, system simulation methods can not be used to validate the developed control algorithm and the uncertainty of test accordingly increases. As mentioned above, this paper presents a model to identify the nonlinear test system using NARMA dynamic neural network and discusses how to make the model parameters in detail. Using the test input-output series data, this network was trained by Levenberg-Marquardt method. Results of verification simulation show the validation of the nonlinear model.
Journal Article

Results of Auto/Steel Partnership (A/SP) Steel Tube Hydroforming Materials and Lubricants Experimental Projects

Over the past twelve years the Auto/Steel Partnership (A/SP) Tube Hydroforming Materials and Lubricants Team has been conducting projects to aid the implementation of tubular hydroforming in automotive applications. The approach taken has been to initially gain a basic understanding of the hydroforming process and potential issues and to then extend learning to real world applications of increasing complexity. The experimental project investigations have encompassed various steel grades with a recent focus on advanced high strength steel (AHSS) and tailor welded tubes (TWTs) in free expansion and corner fill processes using several types of lubricants. Project plans are developed based on identified knowledge gaps, barriers to implementation and technology needs as follows: Effects of forming operations prior to hydroforming including tube making, pre-bending and pre-forming. Forming limits (e.g. forming limit diagrams (FLDs)) and other failure criterion.
Technical Paper

The Combined Braking Energy Management Strategy to Maximize Energy Recovery

Eddy current retarder (ECR) shares a large market of auxiliary brakes in China, but shortcomings of the short continuous braking time and the high additional energy consumption are also obvious. The propose of combined braking partakes the braking torque of ECR. However, the existed serial-parallel braking strategy could hardly balance well the relationship between the braking stability and the energy recovery efficiency. This research puts forward an energy management strategy of combined braking system which aims to maximize energy recovery while ensure the brake stability. The motor speed, the braking request and the state of charge (SoC) of the storage module are analyzed synthetically to calculate the reasonable braking torque distribution proportion. And the recovered energy is priority for using in the braking unit to reduce the additional energy consumption in this strategy.
Technical Paper

Simulation Analysis on Controllability of Hydraulic Electrical Energy Regenerative Semi-Active Suspension

A vehicular hydraulic electrical energy regenerative semi-active suspension(HEERSS) was presented, and its working principle and performance were analyzed. Firstly, configuration and working principle of the HEERSS were described; Secondly, kinetic equation of HEERSS was deduced, and a skyhook controller was designed for HEERSS. The traditional skyhook control strategy should be changed for the characteristic of HEERSS, because the damping force during extension stroke could be controlled, but not in compression stroke. Thirdly, the performance of HEERSS was compared with passive suspension(PS), traditional semi-active suspension(TSS). The simulation results indicated that the performance of HEERSS would be compromise between TSS and PS, but the HEERSS could harvest vibration energy which was advanced than TSS and PS.
Technical Paper

Thermal-Mechanical Fatigue Prediction of Aluminum Cylinder Head with Integrated Exhaust Manifold of a Turbo Charged Gasoline Engine

The present paper describes a CAE analysis approach to evaluate the thermal-mechanical fatigue (TMF) of the cylinder head of a turbo charged GDI engine with integrated exhaust manifold. It allows design engineers to identify structural weakness at the early stage or to find the root cause of cylinder head TMF failures. At SAIC Motor, in test validation phase a newly developed engine must pass a strict durability test on test bed under thermal cycling conditions so that the durability characteristics can be evaluated. The accelerated dynamometer test is so designed that it gives equivalent cumulative damage as what would occur in the field. The duty cycle includes rated speed full load, rated speed motored and idle speed conditions. A transient none-linear finite element method is used to calculate the plastic deformation and thermal mechanical behaviors of the cylinder head assembly during thermal cycling.
Technical Paper

Effect of Circumferential Magnetic Field on Braking Performance of a Direct Vane Magnetorheological Fluid Retarder

The hydraulic retarder used in commercial vehicles can provide hydraulic damping to generate braking torque, reducing the pressure of the braking system on the slope section and increasing the safety. In this paper, the magnetorheological fluid with fast magnetic field reflection characteristics is used to increase the response speed of the hydraulic retarder, which can effectively reduce the response time of the hydraulic retarder. In this paper, the influence of the change of circumferential magnetic field on the braking torque of the magnetorheological fluid retarder is studied.
Technical Paper

Modeling, Simulation and Experimental Analysis of Brake Pedal Feel for Passenger Car

Brake pedal feel plays an important role in the driver's comprehensive subjective feeling when braking, which directly affects the active safety and riding comfort of passenger car. A systematical mathematical model of the vehicle brake system is built in according with the structure and system characteristics of hydraulic servo brake system. A complete hydraulic servo brake system simulation model composed of brake pedal, vacuum booster, brake master cylinder, brake pipe, brake wheel cylinders, brake calipers is established in AMESim. The effects of rubber reaction plate stiffness, rubber valve opening, brake master cylinder piston, brake caliper, brake pipe deformation and friction liner deformation on brake pedal feel are considered in this model. The accuracy of this model is verified by real road vehicle tests under static and dynamic two different conditions.
Technical Paper

CFD Modelling of 3-Way Catalytic Converters with Detailed Catalytic Surface Reaction Mechanism

This paper presents a 3-D CFD modelling of flow and heterogeneous reactions in catalytic converters. The pressure and velocity fields in the catalytic converters are calculated by the state of the art modelling technique for the flow resistance of catalyst substrate. A surface reaction model is applied to predict the performance of a three-way Pt/Rh catalyst. A reaction mechanism with detailed catalytic surface reactions for the 3-way catalyst is applied. The novelty of this approach is the use of a surface chemistry solver coupled with a 3-D CFD code in the entire computational domain of the catalyst substrate that allows flow distribution for complex configurations to be accounted for. The concentrations of the gas species and the site species are obtained. A comparison between the simulation results and the experimental data of a three-way catalyst was made.
Technical Paper

Modeling Energy Absorption and Deformation of Multicorner Columns in Lateral Bending

The frame rail has an impact on the crash performance of body-on-frame (BOF) and uni-body vehicles. Recent developments in materials and forming technology have prompted research into improving the energy absorption and deformation mode of the frame rail design. It is worthwhile from a timing and cost standpoint to predict the behavior of the front rail in a crash situation through finite element techniques. This study focuses on improving the correlation of the frame component Finite Element model to physical test data through sensitivity analysis. The first part of the study concentrated on predicting and improving the performance of the front rail in a frontal crash [1]. However, frame rails in an offset crash or side crash undergo a large amount of bending. This paper discusses appropriate modeling and testing procedures for front rails in a bending situation.
Technical Paper

Preliminary Study of Applying Acupoints Combined with Magnetism Stimuli to Reduce Driver Postural Fatigue

In designing an automobile seat, it is important to minimize the fatigue experienced by the driver resulting from long-term sitting. In this study eight healthy male subjects participated in two group experiments that were A-group and B-group. Acupoints combined with magnetism stimuli were put on to the subjects for reducing postural fatigue in B-group during the simulated driving. The surface electromyography (sEMG) of muscle activity at L4/L5 as well as subjective self-reporting on fatigue were recorded and tested. Analyzing and comparing the EMG median frequency and the subjective evaluations between two groups a conclusion that acupoints combined with magnetism stimuli could reduce the driver postural fatigue was drawn.
Technical Paper

Fuzzy Control of Semi-active Air Suspension for Cab Based on Genetic Algorithms

Semi-active suspension has been widely applied in commercial vehicle suspension in order to get good riding comfortableness. Fuzzy logic control (FLC) has been widely applied in the field of kinetic control because control rule of FLC is easy to understand. But the gain of fuzzy rules and adjustment of membership functions usually depend on experts' experiences and repeated experiments, thus the fuzzy rules and membership functions has strong subjectivity, also are easily affected by environment of experiments, so the main problem of fuzzy logic controller design is selection and optimization of fuzzy rules and membership functions. Genetic Algorithms (GA) is the algorithm that searches the optimal solution through simulating natural evolutionary process and is one of the evolution algorithms which have most extensive impact.
Technical Paper

Driving Path Planning System under Vehicular Active Safety Constraint

Path planning system, which is one of driver assistance systems, can calculate the driving paths and estimate the driving time through the road information provided by information source. Traditional path planning systems calculate the driving paths through Dijsktra's algorithm or A* algorithm but only consider the road information from electronic maps. It is not safe enough for operating vehicles because of the insufficient information of vehicle performance as well as the driver's willingness. This study is based on the Dijsktra's algorithm, which comprehensively considered vehicular active safety constraints such as road information, vehicle performance and the driver's willingness to optimize the Dijsktra's algorithm. Then the path planning system can calculate the optimal driving paths that would satisfy the safety requirement of the vehicle. This study used LabVIEW as a visual host computer and MATLAB to calculate dynamic property of the vehicle.
Technical Paper

Co-simulation Based Hydraulic Retarder Braking Control System

Hydraulic retarder has been widely applied on military vehicles and heavy commercial vehicles because of it could provide great brake torque and has lasting working time [1]. In order to reduce driver's frequent actions in braking process and prevent hydraulic retarder system from overheating, it is need to apply constant braking torque control, this control target has a strict requirement to hydraulic control system design. Many parameters often require repeated test to determine, which increases the R&D cost and extends the research cycle. This paper tries to find a time-efficient research method of hydraulic retarder control system through studying on a heavy military vehicle hydraulic retarder system. Hydraulic retarder model is set up through test data. The hydraulic control system is built based on AMESim. Controller model is set up based on PID control. The whole vehicle brake model is built based on MATLAB/Simulink.
Technical Paper

Research on Road Simulator with Iterative Learning Control

Road simulation experiment in laboratory is a most important method to enhance the design quality of vehicle products. Presently, two main control techniques for road simulation—remote parameter control (RPC) and minimum variance adaptive control—are both defective: the former becomes an open-loop control after generating the drive signals, however the latter is essentially a kind of gradual control. To realize the closed-loop control and increase the control quality, this article brings forward a PID open-closed loop control method. Firstly taking the original road simulator as a group to identify, a nonlinear autoregressive moving average (NARMA) model was built with the dynamic neural network. Subsequently, this plant model was used to build the open-closed loop control system mentioned above. In the closed-loop a discrete PID controller was introduced to stabilize the system, while a P-type iterative learning control (ILC) was adopted to increase the control quality.
Technical Paper

Strength Analysis and Modal Analysis of Hydraulic Retarder

Hydraulic retarder is one of main auxiliary braking devices of the vehicle. When the vehicle is braking, a great pressure from high-speed fluid is received by hydraulic retarder blades. It is difficult to predict rational hydraulic retarder strength, owing to the complexity of the internal flow of oil. An optimal calculation way of hydraulic retarder strength is proposed based on CFD and FEA, concluding a reasonable result. The 3-D model of hydraulic retarder is built in the general CAD software. The model of fluid passage is extracted, according to the condition when the whole flow passage is filled with oil, and imported to CFD software. The inner flow field of hydraulic retarder is analyzed and the hydraulic surface pressure distribution of the hydraulic retarder blade is obtained at the highest rotary speed of turbine wheel.
Technical Paper

Multidisciplinary Design Optimization of BEV Body Structure

Blade Electric Vehicle (BEV) with a light body plays an important role in saving the energy and reducing the exhaust emission. However, reducing the body weight need to meet the heterogeneous attributes such as structural, safety and NVH (Noise, Vibration and Harshness) performance. With the rapid development of finite element (FE) analysis technology, simulation analysis is widely used for researching the complex engineering design problem. Multidisciplinary Design Optimization (MDO) of a BEV body is a challenging but meaningful task in the automotive lightweight. In present research, the MDO is introduced to optimize a BEV Body-in-White (BIW).
Technical Paper

Metal Forming Characterization and Simulation of Advanced High Strength Steels

The remarkable evolution of steel technology in recent years has resulted in the development of new High Strength Steels (HSS) that are increasingly used in today's automobiles. The advanced performance of these grades in ductility and rapid hardening characteristics provides an opportunity to stamp complex geometries with in-panel material strengths far exceeding those of conventional high strength grades of steel. This provides an opportunity to improve an automotive body's performance in crash, durability and strength while reducing the overall weight of the vehicle. An improved understanding of the forming characteristics of these advanced HSS and accurate prediction of the material processing strain will allow vehicle designers to fully explore the opportunities of increased yield, strain hardening, formability and strength and the potential this creates to reduce mass and improve the performance of the automotive body.
Technical Paper

Modelling and Optimization of SCR-Exhaust Aftertreatment Systems

This paper presents a modelling approach to the design optimization of Selective Catalytic Reduction (SCR) systems. The present study is concerned with ammonia slip and conversion efficiency of oxides of nitrogen (NOx), which are two major issues of SCR technologies. A Computational Fluid Dynamics (CFD) code is employed to simulate the mixing characteristics with the purpose of optimization of the concentration distribution of the reducing agent. The physical processes including urea spray atomization, droplet evaporation, urea decomposition and turbulent mixing are accounted for in the modelling method. The Lagrangian discrete phase model is used to describe the urea spray, which contains sub-models for droplet breakup and evaporation. A reaction model of urea decomposition is proposed. The geometry of a specific example includes two air-assisted fluid nozzles, optimized mixing elements of the static mixer, and the SCR converter with two layers of substrates.
Technical Paper

Testing and Modeling of Metallic Multicorner Columns In Axial Crush

The front rail plays an important role in the performance of body-on-frame (BOF) vehicles in frontal crashes. New developments in materials and forming technology have led to the exploration of different configurations to improve crash performance. This paper presents the initial stages of an ongoing study to investigate the effects of the cross section of steel columns on crash performance in automotive applications. Because accurate prediction of the performance of these rails can help reduce the amount of physical crash testing necessary, the focus of this paper is on appropriate testing and modeling procedures for different rail configurations. In the first part of this paper, the Finite Element Analysis (FEA) methodology is presented with respect to correlation with real world tests. The effects of various parameters are described, along with the optimum configuration for model correlation.