Automotive Chassis Research Articles

Characterization of Cut-Edges for Improved Automotive Chassis and Suspension Fatigue CAE Life Predictions

The durability of safety-critical automotive vehicle steel structures has been observed to be influenced significantly by the condition of the component’s cut-edge properties. The importance of the mechanical cut-edge properties on structural durability has been observed due to surface imperfections generated during the cutting process. These then become the preferred initiation sites for fatigue cracks due to the increased intensity of stress applied to a structure. The current work outlines the development of an improved finite element (FE)-based life prediction method, based on strain-life fatigue data of S355MC steel cut-edges. The resulting best method of predicting fatigue lives of cut-edges using the Coffin–Manson method has been determined as providing the best means for predicting the durability of high strength steel components. This process has been validated using a bespoke laboratory test component representative of those in automotive chassis and suspension assemblies. The outcome of this work is that it allows increased reliance on FE life predictions rather than extensive physical laboratory testing.

Structural durability design recommendations for forged automotive aluminium chassis components submitted to spectrum and environmental loadings by the example of a tension strut

The structural durability design of a tension strut of forged aluminium (EN AW 6082 T6), which is a safety component of the automotive chassis, is described. The first step of the structural durability design is the knowledge of the mechanical and environmental loadings. The mechanical loadings are the spectrum loading for the designated normal driving conditions and unintended special event loadings by e.g. braking over road bumps, which are introduced into the component through the wheels. The local stresses imposed on the component are also influenced by kinematics, stiffness, axle mass, dampers, bearings, bump geometry, etc. The environmental loading is the corrosion caused, in winter-time, by salty water on the roads. For design according to the local stress concept, the knowledge of Woehler-curves without and with salt corrosion effects is necessary. On this basis, cumulative fatigue under spectrum loading, which also comprises the special events mentioned, is assessed for a standard configuration and for an optimised one. The numerical results are verified by experimental proofs on the component in the laboratory and on the proving ground as well as by field tests with vehicles.

A Rapid Measurement System For Transmission Efficiency Of Automotive Powertrain

Abstract The current annual inspection of automotives is non-disassembly detection. It can merely measure the power output of automotive chassis, and get inaccurate results. There are few cumbersome and low precision methods for measuring the power output of the engine, and it is difficult to obtain transmission efficiency of automotive powertrain. Anew measuring system is developed by adding reverse dragging system on the basis of the present chassis dynamometer. The system can be used for swift testing of power output of the engine at a particular speed and efficient calculation of the transmission efficiency of automotive powertrain without disassembly. Calibration test is experimented on the force cell. The results show that the proposed system is theoretically correct and practically usable.

EMB 시스템의 모델 기반 센서 고장 검출 알고리즘 개발

The brake-by-wire technology is a new automotive chassis system that allows standard braking operations by electronic components with lighter weights and faster response. The brake-by-wire units such as EMB (Electro-Mechanical Brake) are controlled by electronic sensors and actuators and, thus, the fault diagnosis is essential for implementation. In this study, a model-based fault diagnosis system is developed for the sensors based on the analytical redundancy method. The fault detection algorithm is verified in simulations for various faulty cases. A test bench is built including the EMB unit and the performance of the proposed fault diagnosis system is evaluated through the experiment.

Methods to Determine Torsion Stiffness in an Automotive Chassis

This paper reviews three different approaches to determine the torsion stiffness of an automotive chassis and presents a Finite Element Analysis based method to estimate a vehicle’s torsion stiffness. As a case study, a typical sedan model is analyzed and the implementation of the presented methodology is demonstrated. Also presented is a justification of assuming linear torsion stiffness when analyzing the angle of twist. The presented methodology can be utilized in various aspects of vehicle structural design.

Evaluation of Weldability on the Resistance Spot Welding of DP60 Steels for Automotive Chassis

Evaluation of Weldability on the Resistance Spot Welding of DP60 Steels for Automotive Chassis

A Study of Vehicle Dynamics Stability Based on Fuzzy Control

Electronic Stability Program (ESP) has become the focus of the study in the field of automotive active safety and chassis control in recent years, which was developed from ABS and TCS. ESP mainly works through adjusting the size and the distribution of the longitudinal tire force. ESP can make vehicle produce effective yaw moment to restrain oversteering or understeering, However, ESP is a typical nonlinear, time-delay, time-varying parameter system and its mathematical model is very complex. It is difficult to design the control model by traditional control theory. Fuzzy control does not depend on a precise mathematical model. It is employed to handle complicated questions of nonlinear dynamics. First, in this paper, the7-DOF of vehicle dynamics model based on the H. B. Pacejka tyre model (magic formula) and vehicle reference model were established by using the MATLAB/SIMULINK. Then by using fuzzy control principle to direct at the nonlinear, time varying characteristics of the ESP system, a controller of yaw rate based on fuzzy control was designed. An analysis of the simulation results of J-turn and lane change on slippery road surface shows that the present stability control system based on the yaw rate is effective in maintaining the yaw rate and the sideslip angle within the optimal range, thus improving the vehicle stability.

Application of non-Gaussian closure method in automotive chassis non-linear vibration analysis

Existing non-Gaussian closure method is usually applied to non-linear systems with white noise excitation only. But random vibration of vehicle is excited by correlated road spectrum. To solve vibration responses of a non-linear automotive suspension system, the non-Gaussian closure solution procedure is improved by introducing an additional subsystem which described by a simple differential equation to the vehicle model. A car model with two degrees of freedom against three different types of damping is analyzed based on this proposed method. Some important parameters such as acceleration response, relative loads between the wheel and the road, and passing-through frequency of suspension system were calculated effectively.

Running-in phase of spherical chassis joints—identification of the main influence parameter and implementation in a wear simulation tool

Spherical joints are used in automotive chassis to connect components. They are used in locations where force transmission and at least two rotational degrees of freedom are required simultaneously. The source of wear in such joints specifically in the running-in phase has been an important question in the automotive industry. In this work, the main cause of running-in wear in a specific type of spherical chassis joint is identified experimentally. To verify this identification, simplified tribological tests are conducted on sample geometries of polyoxymethylene representing contact surfaces in spherical joint. The results are used to develop an algorithm which describes the running-in phase in a wear simulation tool. Material tests for polyoxymethylene are conducted in order to identify the stress–strain behaviour which is then used for non-linear finite element simulations in the implemented algorithm. The simplified tribological experiments are subsequently simulated using the modified wear simulation tool for validation.

Analysis of connection element classes and locations and of some structural requirements for the mounting of different superstructure types on transport vehicles

Analysis of connection element classes and locations and of some structural requirements for the mounting of different superstructure types on transport vehicles

Structural durability of forged automotive aluminium chassis components submitted to spectrum loading and salt-corrosion by the example of a tension strut

The structural durability design of a tension strut of forged aluminium (EN AW 6082 T6), which is a safety component of the automotive chassis, is described. The first step of the structural durability design is the knowledge of the mechanical and environmental loadings. The mechanical loadings are the spectrum loading for the designated normal driving conditions and unintended special event loadings by e.g. braking over road bumps, which are introduced into the component through the wheels. The local stresses imposed on the component are also influenced by kinematics, stiffness, axle mass, dampers, bearings, bump geometry etc. The environmental loading is the corrosion caused, in winter-time, by salty water on the roads. For design according to the local stress concept, the knowledge of Woehler-curves without and with salt corrosion effects is necessary. On this basis, cumulative fatigue under spectrum loading, which also comprises the special events mentioned, is assessed for a standard configuration and for an optimized one. The numerical results are verified by experimental proofs on the component in the laboratory and on the proving ground as well as by field tests with vehicles.

Design of Automotive Metal and Composite Chassis Structures

This paper reviews recent patents covering automotive metal and composite chassis structures. Automotive chassis are very complex structures and the variety of different types is vast. This paper attempts to reveal modern chassis design looking at composite structures, bonding methods, front sub-frames, complete space-frames, uni-body, integral frame and monocoque structures. Automotive chassis designs have had considerable developments in recent years. This is attributed to recent legislation taking particular interest in after service disposal and more prominently crash, impact and occupant safety. Automotive manufacturers continue to develop new, innovative and novel approaches to achieving rigidity and stiffness in torsion and bending to achieve optimal suspension geometry, safety and occupant comfort. Recent patents in automotive chassis design refer mainly to stiffening support structures, composite structures, retractable roofs and by far the most common, front crash sub frames. Keywords: Chassis, metal chassis, composite chassis, bonded chassis, crash box, sub frames, spaceframe, monocoque, heat affected zone, epoxy resins, Cycom 977, honeycomb sandwich material, resin transfer moulding, RTM, Cabriolet space-frame, CNC bending, computer controlled welding, fibre-reinforced plastic sheets, multi utility vehicle, Audi spaceframe (ASF) chassis, resilient aluminium alloy, frontal collision, FRP COMPOSITES, torsion beam, Rear sub-frame, Shock absorbing crash element, Honeycomb core profile, noise and vehicle harshness

High performance automotive chassis design: a topology optimization based approach

Automotive chassis design in view of car weight reduction is a challenging task due to the many performance targets that must be satisfied, in particular in terms of vehicle safety. In this paper a methodology for automotive chassis design in involving optimization techniques is presented. In particular, topology, topometry and size optimizations are coupled with fem analyses and adopted in cascade for reaching an optimum chassis configuration. The methodology is applied to the design process of a rear-central engine high performance vehicle chassis. The objective of the optimization process is the chassis weight reduction, yet in fulfilment of structural performance constraints as required by Ferrari standards. The results demonstrate the general applicability of the methodology presented for obtaining the general trusses layout and thicknesses distribution of the structure. The numerical model at this stage shows a significant weight reduction when compared to the chassis of the Ferrari F458 Italia.

The influence of mechanical and CO 2 laser cut-edge characteristics on the fatigue life performance of high strength automotive steels

The cut-edge characteristic properties of automotive structures formed during the mechanical blanking and laser-cutting processes significantly influence fatigue life performance. This factor is becoming increasingly important as S355MC and DP600 high strength steels (HSS) grades under investigation exhibit an increased sensitivity to fatigue cracks initiating from cut-edge regions. It was determined that by manipulating the critical cutting process parameters, clearance in terms of mechanical blanking, and by controlling the interrelationship between power and traverse cutting speed during the laser cutting process can result in optimised fatigue lives being achieved. Optimal fatigue lives were attained by minimising the cut-edge surface damage and by controlling the near edge microstructural deformations during each cutting process. It is the critical significance of fatigue which is the limiting factor towards being able to effectively downgauge steel grades used as automotive chassis and suspension components. This research is some of the first that considers the influence of mechanical and laser cut-edge surface quality and internal properties, which has then been partnered to the critical fatigue performance of HSS grades.

New production strategies for automotive industries

Increasingly, production strategies such as Build-to-Order (BtO) are applied to enhance the flexibility of production networks in automotive industries. Customise-to-Order (CtO) is a promising approach to avoid the efforts involved in coordination and control that result from BtO. Research and development to bring CtO to life is being carried out in the EU-funded project “Automotive Chassis Development for 5-Days Cars” (ACDC).

Design and implement a virtual learning architecture for troubleshooting practice of automotive chassis

In this research, a web-based troubleshooting architecture of automobile chassis is constructed, and it can support distance learning of practical courses in automotive chassis repair and maintenance. This system allows remote learners to operate a practical training module for troubleshooting through the Internet. There are several subjects discussed in this research: (1) developing the learning contents for repairing automotive chassis; (2) building the virtual and interactive platform for browsing and practice of troubleshooting; (3) creating the online evaluation tools and effectiveness analysis. The framework has been tested and implemented in the course, “Automotive Practice: Chassis,” in the Department of Mechanical Engineering at Yung-Ta Institute of Technology and Commerce during the spring semester of 2005. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 18: 512–525, 2010; View this article online at wileyonlinelibrary.com; DOI 10.1002/cae.20219

Corrosion characteristics of coated automotive parts subjected to field and proving ground tests

This project evaluated the corrosion damage over a five-year period of organic coated steels in automotive chassis parts during P/G and field tests using electrochemical impedance spectroscopy (EIS) in a 3.5 wt.% NaCl solution. EIS can provide both quantitative kinetic and mechanistic information about the performance of organic coating/metal systems. The difference in coating performance between the P/G and field test specimens was assessed in relation to the impedance parameters. In particular, it was found that the coating resistance and charge transfer resistance could be used to estimate the difference in corrosion damage between the P/G and field test specimens. The coating performance of the P/G and field test specimens was visually evaluated using SEM. The mechanism of corrosion occurring in the P/G test was similar to that taking place in the field test. The field test environment was about ten times as corrosive as the P/G environment in terms of the electrochemical impedance parameters and surface analysis.

The troubleshooting task implementation in automotive chassis using virtual interactive technique and knowledge-based approach

In this study, a troubleshooting task model of automobile chassis is proposed. It integrates a task implementation method with virtual interactive techniques. Declarative knowledge entities make up the kernel of task model. It makes the task more controllable and automatable. Solution of the knowledge entities is directly used to support automotive chassis repair and maintenance. Furthermore, this system allows learners to operate a practical task module for troubleshooting through the Internet. The framework developed is not dependent on specific automobile style or software configuration and it uses open software (e.g. Java, MySQL, etc.) in the problem reasoning, virtual display and data storage. The framework can achieve the advantages and goals of (1) providing references for technicians in detection of chassis problems to promote repairing skills; (2) constructing a Web-based troubleshooting architecture of automotive chassis that can enhance learners’ (e.g. students, freshman, and drivers) knowledge and techniques; and (3) creating a prototype environment for distance learning to eliminate the limitation of space and time.

Modeling and Simulation of Driveline Test Bench for Automotive Chassis Component System

Vibration in a driveline is presented in this paper. In the experiment, the rear subframe and propeller shafts and axle were composed and mounted with rubber each other. For applying the vibration input instead of the torsional vibration effect of an engine, the shaker was taken. In particular, torsional vibration due to fluctuating forced vibration excitation across the joint between driveline and rear subframe was carefully examined. Accordingly, the joint response was checked from experiments and the FE-simulation using FRF (frequency response function) analysis was performed. All test results were signal processed and validated against numerical simulations. In present study, the new test bench for measuring the vibration signal and simulating the vehicle chassis system was proposed. The modal value and the mode shape of components were analyzed using the model to identify the important components affecting driveline noise and vibration. It could be reached that the simplified test bench could be well established and be used for design guide and development of the vehicle chassis components.

3308 ノンパラメトリック形状最適化手法による自動車部品の多目的剛性設計(OS14 曲面構造の解析と設計III)

In this paper, we present a solution to the multi-objective shape optimization problem for the rigidity design of sheet metal structures. The compliances for multi-loadings are used as indexes of rigidity. The lp norm method is employed to scalarize the vector objective functional of compliances. The volume is set as the constraint. The boundaries to be optimized are assumed to be movable only in-plane direction to maintain the curvatures of the initial shape. The shape gradient function and the optimality conditions are theoretically derived using the Lagrangian approach and the material derivative method.. The traction method is applied to determine the smooth shape variations that minimizes the objective functional, while constraining the shape variations in the normal direction on the sheet metal surfaces. This method is applied to a simple sheet metal structure and a practical automotive chassis component to verify the effectiveness and practical utility for improving the rigidity of sheet metal structures under multi-loading conditions.