Browse Topic: Anti-roll
The design, development, and optimization of modern suspension systems is a complex process that encompasses several different engineering domains and disciplines such as vehicle dynamics simulation, tire data analysis, 1D lap-time simulation, 3D CAD design and structural analysis including full 3D collision detection. Typically, overall vehicle design and suspension development are carried out in multiple iterative design loops by several human specialists from diverse engineering departments. Fully automating this iterative design process can minimize manual effort, eliminate routine tasks and human errors, and significantly reduce design time. This desired level of automation can be achieved through digital modeling, automated model generation, and simulation using graph-based design languages and an associated language compiler for translation and execution. Graph-based design languages ensure the digital consistency of data, the digital continuity of processes, and the digital interoperability of all engineering software tools along the product life cycle (PLC). In this context, they are used to automate the design and development of a suspension system for a Formula student racing car. The automated design consists of an inner design loop for simulating suspension system properties, including a 1D lap-time simulation, and an outer loop for the 3D shape optimization of the modeled anti-roll bar geometry, including 3D collision detection. These nested loops are executed automatically, optimizing the vehicle's kinematics through a particle multi-swarm optimization algorithm. This generic design automation approach for suspension systems leads to improved design quality in significantly less time and at a lower cost.
Improvements in component/system design is a daily challenge these days, always looking for high performance, reduced mass and low costs. The source for the best fit between these factors, coupled with adequate durability performance, is crucial to the success of a given product and this is what motivates engineering teams around the world. The demand for efficient projects with short deadlines for validation and certification is huge and simulation tools focused on accelerated durability and virtual validation are increasingly being used. When developing a new spring for commercial vehicles, lessons learned from the actual loads applied to the suspension are the “key” to a successful project. The loads/stresses from the ground (vertical loads, lateral loads, longitudinal and braking loads) are quite high and, consequently, relevant to the proper definition of the design of the suspension components. The objective of this work is to describe the main development activities faced during a completely new spring development, passing through the design, considering all the limit conditions related to the raw material, lamination process, tempering, rhinestone/shot peening, prefixing and, finally, the load conditions for an adequate fatigue life. The methodology adopted for the definitions of load and fatigue in a bench test is part of this document and, in the end, all iteration results, such as correlation with the application, the MBS and FEA models to be fed again until final validation in a vehicle. This document is a joint development made in partnership between Thyssen Krupp Springs and Stabilizer Bars, Dana Corporation and Volkswagen Truck & Bus (VWTB).
The new corner-based architecture of electrified road vehicles requires a redesign of vehicle suspension components. The design protocol must satisfy the target parameters derived from dynamics requirements. The roll stiffness of the anti-roll bar is a crucial parameter for the handling performance of a vehicle. During the development of a new suspension, the design of the anti-roll bar needs to be modified. To this aim, two-dimensional beam theory models can quickly provide a preliminary design of this component. However, the simplified models might be inaccurate due to the three-dimensional and complex shapes of the bars. The present study aims to overcome this limitation. An analytical beam model based on the spline description of the bar has been developed, which is accurate even for complex geometries of the bars. Assuming a hollow and closed circular cross-section, the model returns the average diameter and the radial thickness needed to achieve the stiffness performance. Three different approaches for the thickness have been analyzed by assuming: (I) a prescribed thickness, (II) a prescribed global mass, and (III) a prescribed maximum value of stress. The first two methods present a uniform thickness along the bar, whereas, in the third one, the thickness varies to obtain the lightest solution. This latter method can be modified to ensure a feasible minimum thickness. Finally, a full-factorial design of the experiments algorithm has been developed to reduce the stress by varying the position of the spline control points. The proposed methods can provide a good preliminary design of the bar and can drive a material replacement process from a lightweight viewpoint.
Roll stability is an important attribute which must be accounted for in heavy trucks. In order to analyze the anti-roll performance of the suspension in the early period of development, engineers will generally use Multi Body Dynamics (MBD) simulation software which can save time in the product development cycle. However, air suspension employs levelling valves to adjust the height by charging and discharging air springs. The air spring is typically modeled as a closed container in the simulation; the stiffness change of the air spring caused by the levelling valve is not considered. In this paper, an air suspension with levelling valves model integrated into the multi-body dynamic model of a 6�4 heavy truck is built with a co-simulation technique to investigate the influence of three types of levelling valves arrangement on the roll performance of the suspension under two typical conditions. Type 1 air suspension is equipped with two levelling valves which are respectively arranged on the middle axle and rear axle. Type 2 air suspension is equipped with two levelling valves which are respectively arranged on the left and right sides of the middle axle. Type 3 air suspension is equipped with three levelling valves which are respectively arranged on the middle axle and the left and right sides of the rear axle. Additionally, the influence of the levelling valves' orifice size on the anti-roll performance of the suspension is analyzed. The results show that Type 2 provides better anti-roll performance, and increasing the size of the orifice is beneficial for the levelling valve to act more quickly.
A single-vehicle crash involving an SUV led to the study of the failure of the anti-sway bar linkage and tire pressure and their relative effects on the handling characteristics of the vehicle. The SUV, having been involved in a rollover, was found with the anti-sway bar drop link disconnected from the suspension lower A-arm assembly. Also, after the crash, the tire pressure in the front tires on the subject vehicle was measured to be above the value specified by the SUV manufacturer; however, the pressure for one of the rear tires was measured to be roughly half of the SUV manufacturer’s recommended pressure. The other rear tire was deflated. The testing described herein addresses the question of what effects the anti-sway bar drop link disconnection or reduced rear axle tire pressure would have on the SUV’s pre-accident handling and driveability. A procedure for evaluating vehicle understeer and oversteer characteristics as specified by SAE J266 was employed to evaluate the yaw and roll plane characteristics of an exemplar vehicle. Testing was designed to include an exemplar SUV in a constant radius, increasing speed maneuver, as well as, single and double lane changes. Additionally, the characteristics of the handling of the SUV was also evaluated relative to low tire pressure for the rear axle tires. Thus, the exemplar SUV was tested with the recommended pressure on both the front and rear axle tires with the anti-sway bar connected and then disconnected; moreover, these tests were repeated with the front tires at the recommended tire pressure and the rear tires at approximately half of the recommend tire pressure according to the SUV manufacturer. From the results of these studies, conclusions regarding the relative effects of a disconnected anti-sway bar and reduced rear axle tire pressure on the stability of the subject SUV could be determined.
The anti-roll bar is an important structural component of the automobile, which can effectively prevent the automobile from rolling and improve the safety of the automobile during steering. In the design of the current anti-roll bar, the stiffness is determined by empirical or oversimplified mathematical models, often not reaching the optimal value. In this paper, eight parameters are used to determine the structure of the anti-roll bar. Combining the Deformation Energy theorem and Castigliano’s theorem, a mathematical model of the stiffness is established. The optimal solution and corresponding parameter values of the mathematical model are obtained by nonlinear programming and genetic algorithm. The influence of structural parameters on the anti-roll bar stiffness is analyzed, and the regular pattern of design is obtained. In addition, the finite element method is used to verify the stiffness solution model. In the experiment, the anti-roll bar designed by the regular pattern is attached to the Baja Racing, and the stiffness of the bar is changed by adjusting the length of the arm of the bar, then the correctness of the design regular pattern is verified by testing the roll response. The improved anti-roll bar can effectively improve the anti-roll stiffness and has a better effect on the cornering stability of the automobile.
Aiming at improving safety (anti-roll performance) with consideration of ride comfort of vehicles during cornering and over road irregularities, magnetorheological (MR) fluid-based semi-active anti-roll bar is investigated in this article. The vehicle roll model with both roll stiffness and roll damping of the vehicle body influenced by the MR anti-roll bar is established to analyze the impact of the torsional stiffness and torsional damping. Combining with the Pareto front of the lateral load transfer ratio (LTR) of the front axle, the optimal roll stiffness and roll damping of a vehicle are determined, and correspondingly the torsional stiffness and torsional damping of the anti-roll bar are determined. And then the mathematical model and multibody dynamic model of the anti-roll bar are established, and the simulation of the MR semi-active anti-roll bar model is carried out via MATLAB/Simscape Multibody. CarSim vehicle model equipped with the MR anti-roll bar is built and a fuzzy controller is designed according to the roll angle and roll rate. Co-simulation based on CarSim and MATLAB/Simulink is conducted to analyze the impact of MR anti-roll bar on vehicle roll performance.
This article presents a robustness analysis study for the model reference controller (“MRC”) of active suspension system. The MRC employs both suspension look-ahead preview and wheelbase preview concepts. The methodology of the MRC is based on the ideal hybrid skyhook-groundhook scheme. A 13 degree of freedom full vehicle model is developed and validated. The engine mass, driver seat, and anti-roll bar are considered in the model. The MRC strategy uses eight proportional-integral-derivative (PID) controllers for both body and wheel control. A gradient based on optimization algorithm is applied to obtain the controller parameters using a cost function including both ride comfort and road holding performance. The robustness analysis of the controller is performed by evaluating the MRC controller performance under different driving conditions, including different road profiles, different vehicle speeds, and different vehicle loading. Furthermore, the effect of the variable design parameters of the suspension system is also investigated. The results showed that the MRC for active suspension provides robust and significant improvement in both ride comfort and road holding performance of the vehicle under different operating conditions.
The active anti-roll bar (AARB) system in vehicles has recently become one of the research hotspots in the field of vehicle technology to improve the vehicle’s active safety. In most off-road vehicles, high ground clearance is required while keeping all wheels in contact with the ground in order to improve traction and maintain load distribution among the wheels. A problem however arises in some types of the off-road vehicles when the vehicle is operated at high speeds on smooth roads. In such condition, the combination of the vehicle’s center of gravity position, large suspension stroke, and soft spring construction creates a stability problem, which could make the vehicle liable to rollover. This article analyzes a comparison of stability performance between passive and active anti-roll bar systems to improve rolling resistance. For active systems, two control strategies will be investigated. The conventional Proportional Integral Derivative (PID) controller is firstly investigated and taken as a reference. Then a modified Proportional Integral Derivative (PID) controller with fuzzy technology is developed and compared to the reference one. A full-car model of 14-degrees of freedom (DOF) associated with the Pacejka tire model is used for the analysis and the simulation of the rollover prevention. The performances of the control strategies are compared and simulated using the MATLAB/Simulink program through a series of stability tests prepared by the National Highway Traffic Safety.
There are many variables involved in the design of a front suspension, such as hardpoints' coordinates, steering geometry or even an anti-roll bar, which could make design difficult and time consuming. The MacPherson strut, due to the simplicity of its construction, less occupied space and low manufacturing cost, is widely used in vehicles in contrast to double wishbone and multi-link suspensions. Although its tuning process still demands time, it can be done with the aid of multibody dynamics simulations, by testing several configurations in a virtual way. In this work, a front suspension model with MacPherson strut is studied, so that the influence of variation of its parameters is analyzed in its elastokinematics behavior and in handling performance of a vehicle.
Development of a passive anti-pitch anti-roll hydraulically interconnected suspension (AAHIS) with the advantage of improving vehicle directional stability and handling quality is presented. A 7 degrees-of-freedom full car model and a 20 degrees-of-freedom anti-pitch anti-roll hydraulically interconnected suspension model dynamically coupled together through boundary conditions are developed and used to evaluate vehicle handing dynamic responses under steering/braking maneuvers. The modeling of mechanical subsystem is established based on the Newton’s second law and the fluid subsystem is modelled using a nonlinear finite-element approach. A motion-mode energy method (MEM) based on the calculation of the motion-mode energy is employed to investigate the effects of an anti-pitch anti-roll hydraulically interconnected suspension (AAHIS) system on vehicle body-wheel motion-mode energy distribution. The performance of AAHIS system and its contribution to the vehicle body-wheel motion-mode energy distribution are demonstrated under combined steering and braking maneuvers. The dynamic response of AAHIS system shows enhanced handling and ride performance as well as improved vehicle anti-roll and anti-pitch properties.
This study presents a hybrid optimization approach of TOPSIS-based Taguchi method and entropy measurement for the determination of the optimal suspension parameters to achieve an enhanced compromise among ride comfort, road friendliness which means the extent of damage exerted on the road by the vehicles, and handling stabilities of a self-dumping truck. Firstly, the full multi-body dynamic vehicle model is developed using software ADAMS/Car and the vehicle model is then validated through ride comfort road tests. The performance criterion for ride comfort evaluation is identified as root mean square (RMS) value of frequency weighted acceleration of cab floor, while the road damage coefficient is used for the evaluation of the road-friendliness of a whole vehicle. The lateral acceleration and roll angle of cab were defined as evaluation indices for handling stability performance. The spring stiffness and shock absorber damping of the front suspension, spring stiffness of the rear suspension, torsional stiffness of the front and rear anti-roll bar are taken as the design variables, which are considered at three levels. A L18 orthogonal array is applied to implement the simulations, and the TOPSIS is thus used to integrate all determined performance criteria of ride comfort, road friendliness and handling stability into a single performance index. Meanwhile, the weights of the quality characteristics are determined by employing the entropy measurement method. Furthermore, the best factor levels are identified according to the Taguchi method principles for single response optimization. Finally, the optimal combination of suspension parameters is confirmed to illustrate the effectiveness of the proposed hybrid optimization method.
Vehicle dynamics is the study of response of the vehicle to driver’s input. Various parameters like location of center of gravity (CG), suspension spring stiffness, wheel alignment parameters, etc. determine the handling behavior of the vehicle. This is a study to investigate the effects of aforesaid parameters on handling characteristics of an intercity bus using MSC ADAMS software tool. Handling performance is determined by evaluating various parameters such as understeer gradient, roll gradient, etc. Understeer gradient is influenced by various parameters like location of CG, tire cornering stiffness, etc. Roll gradient of a vehicle depend on various parameters like vertical stiffness of tires, anti-roll bars (ARB) diameter, location of CG, etc. As a part of this study, four different configurations of MBD models were built to investigate the effect of location of ARB on handling behavior of bus. Several vehicle dynamic tests are virtually conducted on the MBD model of the bus. It was observed that the magnitude of understeer gradient was more in case of bus with front ARB and less in case of bus with rear ARB compared to the bus without ARB. The roll gradient was observed to be minimum for the bus with both front and rear ARB and maximum for the bus without ARB and it was most sensitive to height of CG. The sensitivity analysis revealed that the bus tends to exhibit increased understeer characteristics with the increase in caster, camber, cornering stiffness of rear tires and weight distribution on front axle.
Hydraulic suspension systems with different interconnected configurations can decouple suspension mode and improve performance of a particular mode. In this paper, two types of interconnected suspensions are compared for off-road vehicle trafficability. Traditionally, anti-roll bar, a mechanically interconnected suspension system, connecting left and right suspension, decouples roll mode from the bounce mode and results in a stiff roll mode and a soft bounce mode, which is desired. However, anti-roll bars fail to connect the front wheel motions with the rear wheels', thus the wheels' motions in the warp mode are affected by anti-roll bars and it results an undesired stiffened warp mode. A stiffened warp mode limits the wheel-ground contact and may cause one wheel lift up especially during off-road drive. In contrast with anti-roll bars, two types of hydraulic suspensions which interconnect four wheels (for two-axis vehicles) can further decouple articulation mode from other modes. Based on previous researches, the mass-spring-damper method is used in modeling a sport utility vehicle, the full-car transient modeling approach is utilized for modeling two hydraulic suspensions. An experimental vehicle fitted with these systems has been tested on different type of terrains under the same condition, and the comparison of the experimental results is presented.
In order to improve the handling and stability of a light bus at high speed, a virtual model was established in Adams-Car and its anti-roll bar and bushing parameters were virtually optimized. The tyre mechanical characteristics were firstly tested by using a plate-type tyre tester and the Magic Formula parameters of the tyre were obtained. Then the virtual bus model's handling performance were studied by the simulation of central steering test and steady static circular test. An optimal matching method was put forward. By using genetic algorithm to conduct optimization, the optimised parameters were obtained. After that the anti-roll bar and bushing samples were respectively manufactured. At last, the comparative trials were performed in an automotive proving ground, and the subjective evaluation of the light bus's handling and stability was taken by three specialized assessors. The evaluation result showed that the score of subjective evaluation was 8.6, which was 31% higher than the original bus's. Therefore the handling and stability was improved by the adjustment of front and rear anti-roll bars and bushings and achieved the expected purpose.
In this paper, design methodology of antiroll bar bush is discussed. Typical antiroll bar bushes have slide or slip mechanism, to facilitate the relative motion between ARB and bush. Inherently, this relative motion causes wear and noise of bush. To eliminate stated failure modes, the next generation bushes have been developed, which are using torsion properties instead of slip function. These bushes are already being used in various vehicles. This paper focuses on developing the simple mathematical model, design approach and optimization of ARB bushes. Also, comparison study is presented exploring, the differences and design criteria's between conventional and new generation anti-roll bar bushes.
To integrate the energy-recovery characteristic of the Hydraulic electromagnetic shock absorber (HESA) and the anti-roll characteristic and anti-pitch characteristic of Hydraulic Interconnected Suspension(HIS), a Hydraulic Interconnected Suspension system based on Hydraulic Electromagnetic Shock Absorber (HESA-HIS) is presented. HESA-HIS has three operating modes: energy-recovery priority mode, dynamic performance priority mode and energy-recovery and dynamic performance balance mode. The working principle of HESA-HIS in the three operating modes is introduced, a full vehicle model is built by using the software AMESim, and some simulation tests are conducted by using the vehicle model. The simulation results show that the system can effectively reduce the roll angle of the vehicle, while maintaining good ride performance. Fishhook test results show that the roll angle of the HESA-HIS vehicle is reduced by 80%, compared to the traditional vehicle. Sinusoidal excitation tests show that HESA-HIS system can improve the ride performance to a certain extent by switching the operating modes. Especially in low frequency zone, the HESA-HIS system can not only improve the ride performance, but also regenerate a great deal of energy. It can regenerate the power as 3800watts, when subjected to a sinusoidal excitation with 1Hz in frequency and 50mm in amplitude.
Nowadays, a lightweight component design plays a significant role in both cost of a vehicle and fuel economy in competitive heavy duty truck industry. This paper describes the optimization study of an Anti-Roll Bar (ARB) bracket used in a heavy duty truck. ARB system is used to avoid rolling of a vehicle. In order to measure real forces acting on ARB links, calibration study is performed in laboratory conditions. According to this study, measured strains are correlated with theoretical strain-force curve. After the correlation study, fatigue based topology optimization is made on ARB cast iron bracket according to correlated Road Load Data (RLD) which is performed at Proving Ground. Most of the optimization studies in the literature depend on maximum static loading condition. However, many components or structures in the industry subjected to fluctuating loads when they are in service condition. Small loads in a fluctuating load domain may cause potential danger in the design because there will be damage accumulation on the part when those loads are repeated. The failure of components under cyclic load is called fatigue which plays important role in the design. In this study packaging volume, different road profiles, fatigue cycle limits, material of bracket and manufacturing constraints are taken into consideration. Compared with initial design, the weight of ARB bracket is reduced by 25% while keeping the fatigue life in an acceptable level.
Better ride and comfort, enhanced safety, reliability and durability, lower running cost as well as cost of ownership continue to be challenges for automotive OEMs. Higher fuel efficiency is considered as USP not only for lower running cost but also is hygiene factor from sustainability point of view. This has necessitated the need for Augmenting Light weighting horizon in automotive OEMs. Augmenting this leads to invention of innovative materials and processes for emerging cost competitive market. This paper focuses on technology efforts towards augmenting light weighting Horizon in Automotive. Light weighting concepts being explored by OEMs with the help of automotive component manufacturers from Powertrain - Engines & Transmission, Chassis and Suspension are discussed. The Innovative concepts and case studies covered include Hollow Crankshaft and Camshafts, PM gears, composite / bimetallic brake drum, steering knuckle & leaf spring, hollow Anti Roll Bar (ARB) & Front Axle Beams (FAB), high strength polymers for fuel tank etc.
In this paper, a passive anti-pitch anti-roll hydraulically interconnected suspension is proposed for compromising the control between the pitch and roll mode of the sprung mass. It has the advantage in improving the directional stability and handling quality of vehicles during steering and braking manoeuvres. Frequency domain analysis of a 7-DOF full-car model with the proposed system is presented. The modeling of mechanical subsystem is established based on the Newton's second law. Then the mechanical-hydraulic system boundary conditions are developed by incorporating the hydraulic strut forces into the mechanical subsystem as externally applied forces. The hydraulic subsystem is modelled by using the impedance method, and each circuit are determined by the transfer matrix method. And then the modal analysis method is employed to perform the vibration analysis between the vehicle with the conventional suspension and the proposed HIS. Comparison analysis focuses on natural frequencies and modal shapes with identified eigenvalues and eigenvectors. Experiment setup has been introduced in this paper, The present result offer confirmation that the effectiveness of the anti-pitch anti-roll HIS system in increasing the pitch stiffness and roll stiffness and simultaneously maintaining the bounce stiffness.
The objective of this work is to analyze the main geometric variables that alter the stiffness of the anti-roll bar, which consequently influence the charge transfer between the wheels of the axle, while in a curve, and the body roll. The study was based on the application of this component in a vehicle of simplified construction, but the methodology can also be applied to commercial vehicles. To calculate the stiffness a software, based on the Finite Element Method, was used. In the numerical model was applied a unit force at the ends of the anti-roll bar and was observed the response of the system in terms of deformation. It was verified the change in stiffness caused by varying the position of the bushings that are used to hold the bar, profile cross-section and the change of the opening angle of the arms. Equations from the literature were used to determine the action of centrifugal force on the roll angle of the body, however they do not take into account all the characteristics of the suspension. It was considered the equilibrium condition between the moments of the force acting on the suspension and non-suspended masses and moments of reaction of the springs and anti-roll bar used in suspensions. The ratio between stiffness and weight served as a comparison for the bars, and revealed for what configuration studied was achieved the best effect in reducing rollover and with minor addition of weight to the vehicle. It was possible to obtain a considerable gain in reducing rolling when using the anti-roll bar.
Numerical parameters describing suspension stiffness and damping are required for 3D simulation of vehicle trajectories, but may not be available. This paper outlines a simple, portable method of measuring these properties with a coefficient of variation of 5% on stiffness. 24 of 26 vehicles tested were significantly stiffer in roll than pitch, complicating analyses with models that don't include anti-roll. Suspension parameters did not correlate with static wheel load distribution, and damping coefficient did not correlate with natural frequency. Computer simulations of the speed required to initiate rollover in an S-curve were highly sensitive to the suspension parameters used. When pre-impact tire marks and rollover distance were considered, the simulations became almost insensitive to suspension parameters.
A detailed experimental study to quantitatively compare a roll-plane hydraulically interconnected suspension with anti-roll bar in articulation (warp) mode is presented in this paper. Anti-roll bar as part of conventional vehicle suspension system is a standard configuration widely used in road vehicles to provide the essential roll-stiffness to enhance vehicle handling and safety during fast cornering. However the drawback of anti-roll bar is apparent that they limit the wheels' travel on uneven road surface and weaken the wheel/ground holding ability, particularly in articulation mode. Roll-plane Hydraulically Interconnected Suspension (HIS) system, as a potential replacement of anti-roll bar, could effectively increase vehicle roll-stiffness and provide the tunable damping effect, without compromising vehicle's flexibility in articulation mode. This paper presents the finding of an experimental analysis of roll-plane HIS system in comparison with anti-roll bar on a sport utility vehicle in articulation mode. The test vehicle has three different configurations for comparison: 1) conventional suspension without anti-roll bar, 2) with anti-roll bar, and 3) with roll-plane HIS. The test results demonstrate that in articulation mode, anti-roll bar limit wheel's travel, while HIS system has a negligible effect on wheel's travel. A detailed analysis and discussion of test results are provided to conclude the paper.
Mainly motivated by developing cost-effective vehicle anti-roll systems, hydraulically interconnected suspension has been studied in the past decade to replace anti-roll bars. It has been proved theoretically and practically that hydraulic suspensions have superior anti-roll ability over anti-roll bars, and therefore they have achieved commercial success in racing cars and luxury sports utility vehicles (SUVs). However, since vehicle is a highly coupled complex system, it is necessary to investigate/evaluate the hydraulic-suspension-fitted-vehicle's dynamic performance in other aspects, apart from anti-roll ability, such as ride comfort, lateral stability, etc. This paper presents an experimental investigation of a SUV fitted with a hydraulically interconnected suspension under a severe steady steering maneuver; the result is compared with a same type vehicle fitted with anti-roll bars. Furthermore, an insight of how the hydraulic suspension response to extreme maneuvers has been presented, which is of great interest to the optimization of the hydraulic suspension design. Real time simulations are used to assist the experiment to provide a complete picture of the hydraulic system response. The findings are discussed.
In this study, a three-axle vehicle model established with ADAMS/Car is first correlated with field test data from quasi-static tilt table and highly dynamic NATO double lane change maneuver tests, respectively. It is then applied to predict the vehicle static rollover threshold (SRT) and dynamic rollover threshold (DRT). With the optimization approach proposed in this study it is possible to efficiently tune the anti-roll bar stiffness at each axle, to either maximize SRT or DRT, or balance both. The sensitivity results derived from the optimization iteration process can be applied to effectively size the three anti-roll bars that balance the static and dynamic roll stability performances. The proposed method can be potentially applied to include other parameters to address the roll stability issues and beyond.
This paper describes dimensional synthesis, analysis and performance optimization of a three-link rigid-axle suspension system. This suspension architecture has two longitudinal links and panhard rod as a transverse link. In case of rigid axle with three links, roll stiffness is primarily governed by springs, anti-roll bar, suspension link dimensions and its orientations. Because of suspension architecture, the bushings connecting the longitudinal link to axle will also contribute to the suspension roll stiffness. Typically, this contribution is comparable to the contribution due to the suspension springs. Hence, this paper explores the process of reducing roll stiffness of three-link rigid-axle suspension by identifying and changing high impact parameters. In the multi-step process, the first step is to evaluate the kinematics and compliance performance. This analysis is performed using "ADAMS®" - the multibody dynamics analysis software. Out of all kinematics performance parameters, roll stiffness is one of the major parameters which has significant effect on ride and handling characteristics of vehicle. Handling performance of a vehicle is a critical performance attribute defining and differentiating a vehicle from its competitors. Typically, with such suspension architecture, problem of excess rear roll stiffness is common. Reduction in spring stiffness is not an option as its specification is governed by other vehicle performance viz. ride comfort, load capacity, etc. Hence, a detailed study has been performed to understand the governing design variables and its sensitivity to the performance metrics (in the present case, the roll stiffness). The prominent design variables that have been studied are Side view axle bush separation, Side view longitudinal link inclination, and Top view axle side bush separation (between LH and RH). With these design variables DOE is performed using Taguchi Method of orthogonal array. The results of this study have been presented to aid intuitive inferences. The key benefit of this study is with minimum number of experiments understanding sensitivity of the governing design variables and therefore a definite dimensional synthesis procedure to design a required suspension performance.
Items per page:
50
1 – 50 of 86