Car Suspension Research Articles

Multi-objective optimization of a sports car suspension system using simplified quarter-car models

In this paper, first, the vibrational governing equations for the suspension system of a selected sports car were derived using Lagrange's Equations. Then, numerical solutions of the equations were obtained to find the characteristic roots of the oscillating system, and the natural frequencies, mode shapes, and mass and stiffness matrices were obtained and verified. Next, the responses to unit step and unit impulse inputs were obtained. The paper compares the effects of various values of the damping coefficient and spring stiffness in order to identify which combination causes better suspension system performance. In this regard, we obtained and compared the time histories and the overshoot values of vehicle unsprung and sprung mass velocities, unsprung mass displacement, and suspension travel for various values of suspension stiffness (KS ) and damping (CS ) in a quarter-car model. Results indicate that the impulse imparted to the wheel is not affected by the values of CS and KS . Increasing KS will increase the maximum values of unsprung and sprung mass velocities and displacements, and increasing the value of CS slightly reduces the maximum values. By increasing both KS and CS we will have a smaller maximum suspension travel value. Although lower values of CS provide better ride quality, very low values are not effective. On the other hand, high values of CS and KS result in a stiffer suspension and the suspension will provide better handling and agility; the suspension should be designed with the best combination of design variables and operation parameters to provide optimum vibration performance. Finally, multi-objective optimization has been performed with the approach of choosing the best value for CS and KS and decreasing the maximum accelerations and displacements of unsprung and sprung masses, according to the TOPSIS method. Based on optimization results, the optimum range of KS is between 130 000–170 000, and the most favorable is 150, and 500 is the optimal mode for CS .

HIZ TÜMSEĞİ PROFİLLERİ İÇİN YARIM TAŞIT MODELİ YAKLAŞIMI KULLANILARAK AKTİF SÜSPANSİYON SİSTEMİNİN MODELLENMESİ VE SİMÜLASYONU

Driving comfort and safety are important research areas in engineering and have been the subject of many studies. The objective of this work is the modeling and simulation of the disruptive effects coming from the road for the car suspension system. Disruptive effects from the road are modeled as bump geometry which represents the speed trap. There are different vehicle models are used in suspension control systems. The half-car model is selected in this study which has four degrees of freedom; the vertical movements of the front and rear axle, pitch and vertical motions of the vehicle body. The suspension system is the most important part of the vehicle that increases driving safety and passenger comfort by reducing road effects. The actively controlled suspension system is a type of vibration suspension structure popular in both the academic research and industrial application. As the control design, Linear Quadratic Regulator (LQR) controller is designed for half car active suspension system. In order to demonstrate the performance of the designed controller, a comparison has been made for the active and passive states for the suspension system. The designed controller was implemented to the active suspension control of the vehicle model modeled in Matlab-Simulink environment. Bump type speed trap profile is modeled as an input of the system. Simulation results show that the disruptive effects from the road is effectively damped when the active suspension is activated.

Selection of the optimum decomposition level using the discrete wavelet transform for automobile suspension system

This paper discusses the determination of the optimum decomposition level by using the discrete wavelet transform (DWT) method for an automobile suspension system. The DWT method has been widely adopted in signal processing analyses. For the purpose of this study, a car was driven on two types of road conditions: highway and bumpy. Strain signals were measured based on the response gained from the coil spring. These signals were decomposed into 14 levels of decomposition, in which the percentage of wavelet energy for Levels 1 through 4 were 100 % similar to the original signals for both roads. The results were evaluated by comparing the fatigue life values for each decomposition level to the original signal. Based on the comparison of both roads, levels 1 to 3 show a difference of less than 20 % in fatigue life compared to the original signal. Thus, the accuracy of wavelet-based signal processing has proven to be applied in the fatigue durability analysis for automotive applications.

Experience with use of HIL simulators in control engineering course

The goal of the paper is to share experience with the use of hardware-in-the-loop (HIL) simulators in a control-engineering course being taught at the University of West Bohemia. The hardware simulators were introduced recently in the course curriculum aiming to get more realistic application scenarios for the students. They allow simple explanation of the concepts of model-based systems engineering in a form close to the workflow used in industrial practice. The achieved results show some significant benefits when compared to former course content, which relied on numerical simulations only. The paper presents one of the application use-cases dealing with the problem of active car suspension control. Individual phases of the control system development as done by students are explained step by step, revealing the main benefits of the hands-on experience with the physical setup.

Modeling of Tire Vertical Behavior Using a Test Bench

Tire models are of great importance for precise investigations of vertical vehicle dynamics, including vehicular safety and riding comfort. An adequate modeling of the tire is crucial to properly reproduce vehicle vertical behavior in simulations and to evaluate the influence of the tire in the overall performance of the suspension system. This paper introduced vehicle single-point tire models and, thereafter, investigated the influence of the excitation frequency and inflation pressure on the damping and stiffness coefficients of the proposed tires experimentally. In this manner, a test-bench was used to obtain the model parameters of a light vehicle tire and a motorcycle tire. Given the obtained results, it has been observed that both factors have a significant effect on the parameters of the proposed tire models. Moreover, a quarter car suspension model was investigated using the modelled tires to illustrate the influence of the correct characterization of the tire on the vertical suspension performance.

Self-assembled liposome from core-sheath chitosan-based fibres for buccal delivery of carvedilol: formulation, characterization and in vitro and ex vivo buccal absorption.

A novel drug delivery system based on self-assembled liposome from core-sheath nanofibres for buccal delivery of Carvedilol (Car) was explored. The Car-loaded PVP/PC (phospholipids) layer was coated with chitosan-PVA (CS-PVA) or CS-PVP to increase retention period in the mouth. SEM, confocal laser scanning microscopy (CLSM), XRD and Fourier transform infrared spectroscopy were applied to characterize fibre diameter and drug state. Appearance, particle size and encapsulation efficiency of self-assembled liposome were investigated by transmission electron microscopy (TEM) and Zeta-sizer Nano. The dissolution test and permeation tests across porcine buccal mucosa and TR146 cell model also were run. Confocal laser scanning microscopy and XRD confirmed the core-sheath structure of coaxial fibre and non-crystalline form of Car, separately. TEM demonstrated the sphere morphology of self-assembled liposome from spun fibres after contacting water. The dissolution test implied the ratio of PC to Car had a huge impact on drug release. The permeation tests across porcine buccal mucosa and TR146 cell model showed similar result, namely our formulation having a better permeation performance than Car suspension. The indirect toxicity against TR146 cells presented 5mg/ml (or lower) of fibre extraction was safe for cells. These researches exhibited this drug delivery system was promising and advantageous for Car buccal delivery.

Fatigue Reliability Assessment of an Automobile Coil Spring under Random Strain Loads Using Probabilistic Technique

This paper presents a mathematical model to estimate strain-life probabilistic modeling based on the fatigue reliability prediction of an automobile coil spring under random strain loads. The proposed technique was determined using a probabilistic method of the Gumbel distribution for strain-life models of automobile suspension systems. Strain signals from different road excitations in experimental tests were measured. The probability density function of the Gumbel distribution was considered to estimate model parameters using maximum likelihood estimation (MLE). The Akaike information criterion (AIC) method was performed to specify which model can estimate the best fit model parameters. Results demonstrated a good agreement between the predicted fatigue lives of the proposed probabilistic model and the measured strain fatigue life models. The root-mean-square errors (RMSE) based on the Coffin–Manson, Morrow, and Smith–Watson–Topper strain-life models were approximately 0.00114, 0.00107, and 0.00509, respectively, indicating a high correlation with the proposed model and experimental data. The results demonstrated that the proposed probabilistic model is effective for the fatigue life prediction of automobile coil springs using strain and stress fatigue life approaches.

Assessment of Production Process Capability in the Serial Production of Components for the Automotive Industry

Abstract The article deals with the assessment of production process capability in the serial production of plastic components. The plastic component was used for analysis. Component is used in the automotive industry in car suspension shock absorbers. Assessing the capability of the product’s manufacturing process is very important. The aim of the present paper is to measure the dimensional characteristics of a thermoplastic product as a monitored quality feature. The analyzed product is manufactured in an eightfold injection mold by injection technology. The products from each injection mold cavity were considered separately. Process capability was assessed using capability indices. Process variability and centering were evaluated. Based on the analysis we can say that the production process is in excellent condition.

A method for the identification of dynamic characteristics car suspension materials

Identification of dynamic characteristics of the machine suspension materials is required for troubleshooting and improving the ride quality. The method of identifying the suspension materials characteristics, based on the application of needle-shaped variation of the L.S. Pontryagin dynamical system to the invariant features of the dynamic system actual movement is presented in this study. The use of the needle-shaped parameters variation to the Hamilton-Ostrogradskyi action integral gives a condition of the objective functional minimum in the form of the maximum principle with the exception of the consideration of the vector of conjugate variables. As a result, the computational costs are reduced, the task of identification and optimization is simplified the convergence and accuracy of the algorithms is improved [1 - 5].

State estimation and damping control for unmanned ground vehicles with semi-active suspension system

The new type of transportation based on intelligent driverless vehicles will bring great changes to people’s travel modes and put forward higher requirements for the ride comfortability of vehicles. This paper presents a new observing algorithm to estimate the suspension states in real time and cooperate with sliding mode controller to improve the ride comfortability. First, the nonlinear model of an air suspension system equipped with a continuously controllable damper is described in detail. Then, this nonlinear suspension model is linearized precisely based on the differential geometry theory; a linear Kalman filter observer is implemented for this linearized model; through the coordinate reverse transformation, the designed linear observer is transformed into a nonlinear one, which will be suitable for the original nonlinear system, so that, the proposed state observer can estimate all the states of the nonlinear quarter car suspension system. Then, in this nonlinear suspension system, a model reference sliding mode controller is designed to continuously control the damping force to improve the ride comfortability. Finally, the effectiveness and advantage of the proposed feedback linearization Kalman observer is illustrated by comparing with a traditional extended Kalman filter observer. The simulation research shows that the proposed feedback linearization observer enjoys a better estimation accuracy, higher operation efficiency, and greater control performance while cooperating with the sliding mode controller in ride comfortability control.

Reliability assessment on automobile suspension system using wavelet analysis

Purpose The purpose of this paper is to focus on the reliability assessment on the basis of automobile suspension fatigue life using wavelet decomposition method. Design/methodology/approach The discrete wavelet transform (DWT) of automobile coil spring signal is implemented as a response to different road surfaces. A reliability analysis is applied to determine the potential of the wavelet implementation in fatigue life analysis. The signals used in this study are highway and rural road. Findings On the basis of the implementation of wavelet decomposition method, low-level decomposition replicates the original signals in comparison with high-level decomposition. The fatigue life of low-level decomposition lies in the 2:1 and 1:2 correlation graph. The percentage difference for mean cycle to failure presents low values for low-level decomposition, with 44.31 per cent for highway and 44.20 per cent for rural road. The percentage of difference for high-level decomposition is high. Originality/value The determination of fatigue life analysis by using the DWT method is suitable for low-level decomposition. High-level decomposition is considered noise that cannot be eliminated and does not contribute to the failure of the structure.

Enhancing the Closed Loop Performance of Semi-active Suspension System with I-PD Controller

This paper aims to investigate for the control quarter car semi-active suspension system using PID controller. In the study, simulation and transfer function models are constructed and used for the control of relative displacement of semi-active suspension system. The conventional PID controller is designed by using Ziegler-Nichols method and it used for the control of suspension system. The closed loop performance of PID controller is improved through reducing the derivative gain value. It shows that, the peak overshoot of closed loop responses are sluggishly reduced. The modified forms PID controller such as PI-D and I-PD controllers are furthermore used for the control of suspension system. From the results, the I-PD controller deliver better closed loop performance compared with PID and PI-D controllers. The control of suspension system using I-PD controller provide superior closed loop performance by means of minimization of peak overshoot and settling time.

Design Modification and Improvement on Automobile Suspension System

Now days the air suspension system is used in all commercial vehicles like buses and trucks. In the recent era the peoples are looking for Air suspension in Light Commercial Vehicles. The Air suspension system comprises of many brackets, from them we selected the parallel link bracket. The existing Parallel link bracket is consists of more number of supporting plates, tubes, welding and also it having more weight. This type of brackets ate mounted in vehicle chassis with the help of bolted joints. The weight of the Air Suspension System is more important in the aspect of vehicle mileage. All the major OEM's are pressurising for reducing the weight of the air suspension system. By assimilate the optimized process or process route, removing the unfavourable materials or processes and decreasing the number of parts in mandatory area, mean while without affecting the requirement of the component and also reducing the weight of the components or assembly.

The Influence of the Conditions of Use and the Type of Model Used on the Vertical Dynamic Responses of a Car Suspension

The article presents a study of the influence of vehicle’s conditions of use, such as road class, vehicle speed or its load, on its vertical dynamic responses. In the article only the kinematic excitations were analysed, as these are more common than the dynamic ones. The road profiles were artificially generated according to the ISO 8608 standard, which classifies roads based on power spectral density of excitations which they generate. Ride safety, ride comfort and fatigue strength indicators were computed. Ride safety was defined by the DLC – Dynamic Load Coefficient. Ride comfort was judged taking into consideration the recommendations from the ISO 2631 standard (which contains the information on vibration frequencies and their effect on human body, as well as the allowed exposure times to given vibrations) by calculating root mean square values of sprung mass accelerations for bandwidths defined in the standard. Load spectrums for the fatigue analysis were created using forces generated in a simulation as a basis and further research venues were proposed. Lastly conclusions were drawn from the results, that imply that linear models are sufficient for many standard applications on roads of acceptable quality, however the use of non-linear models is recommended in fatigue strength analysis regardless of conditions of use.

Sliding Mode Controller for Different Road Profiles of Active Suspension System for Quarter-Car Model

The main purpose of the vehicle suspension system is to induce more comfortable riding and well handling with the road inputs. The principal objective of this research paper is to reduce vibration and improve passenger comfort of car suspension through the sliding mode controller. The mathematical model of passive and active suspensions mechanism for a quarter car model that subjects to excitation from road profiles is obtained. The active suspension system is developed through sliding mode control for a quarter car model. The performance of the sliding mode control is evaluated through a simulation approach using MATLAB and SIMULINK toolbox. The simulated results plotted in the time domain and root mean square values. It is concluded that the active suspension using a sliding mode controller improves the ride comfort and reduces vibration.

Energy-harvesting variable/constant damping suspension system with motor based electromagnetic damper

Energy-harvesting suspension is very important to improve the energy efficiency of vehicles, especially for electric vehicles. A novel energy-harvesting variable/constant damping suspension system with motor based electromagnetic damper is proposed in this paper. The method attempts to make following contributions: The vehicle vibration energy is not only harvested from the suspension system, but also controlled to store in the battery for further usage. Moreover, the damping of the suspension system is able to be controlled as wish, to be constant or to vary with road conditions. The performance comparison with conventional suspension equipped with an oil damper is carried out by simulation and experiments. The effect of the moment of inertia on the suspension performance is investigated. To experimentally validate the proposed method, a scaled quarter car suspension validation platform is established. The experimental results show that the damping can be controlled to be constant as the conventional oil damper, and also be variable as wish. The proposed energy-harvesting suspension can recover energy from vehicle vibration to store in the battery for further usage with high efficiency, which is as high as 35.24% improvement compared with previous studies. Meanwhile, the damping coefficient can also be regulated in real-time accurately.

Imprecise random field analysis with parametrized kernel functions

Abstract The application of isotropic random fields in engineering analysis requires the definition of their first two central moments, as well as their covariance function. In general, insufficient data are available to make a fully objective crisp estimate on these quantities, and hence, subjectivity enters implicitly into the analysis. The framework of imprecise probabilities is gaining popularity in this context, as it allows to explicitly separate the epistemic uncertainty, present due to data insufficiency, from the aleatory nature of the random parameters. However, an approach that is capable of handling imprecision in the complete definition of the imprecise random field is lacking to date. This paper proposes a framework for imprecise random field analysis with parametrized covariance functions. As such, the functional form of the covariance function is assumed to be known deterministically, whereas the governing parameters are subjected to imprecision. First, a comprehensive analysis of the effect of imprecise random fields, given imprecision on both the mean and auto-covariance structure, is presented. It is shown that the discretization of an imprecise random field, given interval-valued correlation lengths cannot be performed using interval arithmetical procedures as the resulting basis functions are in that case no longer a complete basis on L 2 . Therefore, an iterative procedure is proposed where the bounds on the imprecise random field basis are determined via an optimization procedure. This procedure provides exact bounds on the response of a system in case the system is monotonic with respect to the random field realizations. Two illustrative case studies on a mass-damper-spring system and a dynamic state-space model of a car suspension are included to illustrate the methodology. These case studies illustrate that indeed a separation between aleatory and epistemic uncertainty is possible in random field analysis, and hence, more objective results are obtained at only slightly increased computational cost.

Study regarding the influence of the flexible lamella on the elastic characteristic for a suspension with longitudinal torsion bars

A main component of the car suspension is the stabiliser bar, that has the role to reduce the roll oscillations, and it is constructively materializes, within the conventional suspension, via a transversal torsion bar connected direct and indirect between the wheels of the axle. There are constructive solutions of suspensions with torsion bar as elastic element, longitudinal disposed, and that replaces the conventional stabiliser bar with a flexible lamella connected between the ends of the longitudinal torsion bars. So, the flexible lamella has two functions: reduces the roll oscillations and works as an additional elastic element of the suspension. Via this second function it is improved the elastic characteristic aspect of the suspension with positive consequences on the comfort and safety. The paper aims to highlight this influence by the experimental determination of the elastic characteristic of the suspension with and without lamella and the comparing of the two elastic characteristics. It is carried out and a complex theoretical model of the suspension with longitudinal torsion bars and flexible lamella, validated via the experimental research, that allows the optimization of such a suspension.

Investigation of Distortion and Temperature Distribution during Assembly of a Rail Car Suspension Arm

Investigation of Distortion and Temperature Distribution during Assembly of a Rail Car Suspension Arm

Response characteristics of car seat suspension using intelligent control policies under small and large bump excitations

Integration of semi-active devices in Automotive Seating System (ASS) with intelligent control policies help attenuation of the vibration transmitted to the occupant. The current work investigates the effectiveness of a semi-active magnetorheological (MR) damper with ASS for a quarter car model with the application of suitable control algorithms. The system controller calculates the desired damping force using proportional integral derivative (PID), skyhook on/off, PID tuned using genetic algorithm (GA), skyhook continuous and modified skyhook controllers. The signum function damper controller estimates the command voltage required for tracking the desired damping force. The displacement and acceleration of the passive seat system was compared with the semi-active seat suspension system in time and frequency domains. The results from the frequency domain shows that the lowest resonance peaks for the seat system can be achieved using the modified skyhook control policy. The effectiveness of the modified skyhook controller is evaluated in terms of peak to peak (PTP) acceleration, root mean square (RMS) acceleration, frequency weighted RMS acceleration, seat effective amplitude transmissibility (SEAT), vibration dose value (VDV) and crest factor (CF) for enhancing the ride quality. The modified skyhook controller can dissipate the energy better than the passive system. The modified skyhook controller increased the occupant ride quality of SEAT, VDV and CF by 30.41%, 52.84% and 11.62% on account of small bump excitation and 31.76%, 53.27% and 11.02% on account of large bump excitation compared with passive system. The modified skyhook control policy attenuates the vibration better than other control policies addressed in this paper.