Car Suspension Research Articles

Experimental and simulation investigation of vertical response of stepped torsion bar spring for light motor vehicle suspension system

The straight torsion bar spring is widely used in automobile and military tankers suspension systems due to less occupation of space and high weight bearing capacity. In this present work, the vertical response of Stepped Torsion Bar Spring (STBS) in Light Motor Vehicle (LMV) suspension is investigated. The STBS consists of two segments in series. The segment-1 is larger diameter when compared to that of segment-2. Three cases of diameter ratio and length ratios combination of STBS are experimented and simulated. A 2-DOF (Degree of Freedom) quarter car model test rig is designed for the experimental work. A harmonic excitation is given as road input though a Cam. The damped and undamped vertical response and frequencies of STBS are experimented. The vertical response and its spectrum analysis are plotted and better responses of the low stiffness STBS is identified for comfort ride and the results are compared with MATLAB Simulink results. The results of the suspension parameters such as tire stiffness, damping coefficient of shock absorber, stiffness of STBS, internal damping of STBS and torsional to linear stiffness are investigated.

Magnetorheological Fluid-Based Bending Actuator for Magnetic Sensing

Magnetorheological (MR) fluids have applications in diverse areas such as automobile suspension, architecture, and vibration control due to their fast response, wide range of controllability, and temperature resistance. However, traditional MR fluids-based applications for robotics lack the capability of sensing that can provide information about the environment. In this letter, we present a MR fluid-based bending actuator for magnetic sensing by integrating a strain gage into the actuator. Its deflection can be detected by reading the change of resistance when the actuator deflects under different external magnetic fields. Subsequently, we obtain the relationship between the magnetic flux density and the deflection by deriving an analytical model. To demonstrate the magnetic actuation capability of the actuator, we fabricate a fish-like robot whose tail is composed of the actuator. We further conduct simulations and experiments to validate the analytical model of magnetic sensing. This model shows good agreement with the simulation and experiment results. We validate the actuator for magnetic sensing by demonstrating that it can exhibit a good tracking response of dynamic signals (maximum absolute error smaller than 2.5 mT). The results illustrate that the MR fluid-based bending actuator has the potential to use in the environmental inspection.

PH/redox/α-amylase triple responsive metal-organic framework composites for pest management and plant growth promotion

The development of stimuli-responsive controlled release formulations is a promising strategy to enhance the utilization efficiency and reduce the environmental pollution of pesticides. In this work, a smart pH/redox/α-amylase triple stimuli-responsive pesticide delivery system was constructed by bonding carboxymethyl starch (CMS) with metal-organic frameworks (MIL-101(Fe)–NH2 nanoparticles) which loaded with CAR (CAR@MIL-101(Fe)-CMS nanoparticles). The results indicated that the loading capacity of CAR@MIL-101(Fe)-CMS nanoparticles for CAR was approximately 18.3% and the CMS attached on the surface of CAR@MIL-101(Fe)–NH2 nanoparticles could protect CAR from photolysis effectively. Meanwhile, the coated CMS and metal-organic framework structure of the nanoparticles could be decomposed and consequently release pesticide active ingredients on demand when CAR@MIL-101(Fe)-CMS nanoparticles were metabolized by glutathione and α-amylase in the insect alkaline midgut. The bioactivity survey confirmed that CAR@MIL-101(Fe)-CMS nanoparticles had a longer duration in controlling Spodoptera frugiperda larvae compared to CAR suspension concentrate. In addition, the MIL-101(Fe)-CMS nanocarriers were safe for the growth of maize and could be used as fertilizer to promote the growth and development of crops. Thus, this smart stimuli-responsive pesticide-fertilizer all-in-one combination strategy has great potential in pest management.

Modelling a uniaxial inerter in a 2D or 3D environment: Implications of centripetal acceleration

The inerter completes the force-current analogy between mechanical and electrical components, providing the mechanical equivalent to the capacitor. As such, it is a two-terminal passive element that, when implemented ideally, is normally said to generate a force proportional to the relative acceleration between its two terminals. However, this is applicable only if the inerter does not rotate, so the only relative motion between the device's terminals is axial. In many applications, this restriction is acceptable, such as in car suspension systems. However, in this paper, it is shown that the relationship between the terminal accelerations and the generated force is more complex if the inerter is used in a 2-dimensional (2D) or 3-dimensional (3D) environment, such as within a multi-bar mechanism (e.g., robotic arms or railway pantographs). Specifically, the inerter force is not given by simply the relative acceleration between the two terminals. The centripetal acceleration, resulting from the rotation of the inerter, needs to be accounted for to find the second derivative of the inerter length, which defines the generated force. Two case studies are presented to demonstrate the effects of this normally neglected centripetal acceleration term. It is shown that when an inerter is operating in a 2D or 3D environment, significant errors may occur in evaluating the inerter force and also the system response if the centripetal acceleration term is neglected. Equations are provided for both modelling the inerter in different coordinate systems and for incorporating the inerter in 2D and 3D multibody systems.

Validation of machine learning approaches for estimating wheel fatigue loads at the front suspension of a race car during track driving

AbstractThe wheel loads of a race car have been estimated in view of structural durability assessments. First, the front left double‐wishbone suspension of a rear‐wheel‐drive race vehicle has been instrumented; then, wheel loads have been estimated by means of four approaches: (i) a geometric matrix (GM) method, (ii) a feedforward neural network (FNN) approach applied to the fully instrumented suspension (FIS), (iii) a FNN approach involving a reduced number of sensors (the partially instrumented suspension (PIS)) and an inertial measurement unit (IMU), and (iv) a linear modeling approach (LM). After having trained the FNNs by using suspension signals acquired in a racetrack as inputs and related tire forces measured with the GM method as targets, the FNN‐based methods have been validated on three different racetracks by comparing the estimated loads with those estimated by means of the GM method. According to the results achieved, the FNN approaches are effective for the estimation of the wheel forces.

Investigating The Failure of Leaf Springs in Automobile Suspension on Ghana Road

This study investigates the failure of leaf springs used in the suspension system of heavy-duty vehicles in Ghana. Primary and secondary data were collected using both open and closed-ended questionnaires. Welders and fabricators of Sarkyoyo enterprise at the Suame Spare parts dealership area in Kumasi were engaged in the survey. The elastic strain and stress mathematical models were used to determine the stress points in a loaded leaf spring with the aid of ANSYS. The factors considered in the analysis were the leaf spring SAE design specification, the recommended Ghana Highway Authority load limit for heavy-duty vehicles, and the terrain. Analysis was done for both the standard and variable curvature leaf springs. The mode of failure was found to be fatigue loading. The causes of failure were determined to be loaded beyond the recommended 43 tons per wheel limit, bad roads, and reckless driving. It was also observed that loading causes the edges of the leaf spring to bend outwardly from the top, making the edges more prone to failure. Results further showed that the leaf spring with variable curvature recorded strain energy 2.5 times higher than the standards leaf spring.

Formula omitted] and [formula omitted] Control with sector bound optimization for Continuous Time Markov Jump Lur’e Systems

This paper addresses the H2 and H∞ control of Markov Jump Systems subject to a class of nonlinearities that include them on the Lur’e system framework, with sector slope optimization. The proposed controllers are robust to nonlinearities belonging to a sector. We propose mode-dependent controllers; in other words, the Markov mode θ(t) is available to controllers. The design of such controllers considers the optimization of the H2 and H∞ costs as well as the sector slope, which determines the class of accepted nonlinearities. The results are illustrated through two practical examples: coupled electrical machines and the semi-active suspension of a quarter car.

Multiphysics Design of an Automotive Regenerative Eddy Current Damper

This research presents a finite element multi-physics design methodology that can be used to develop and optimise the inherent functions and geometry of an innovative regenerative eddy current (REC) damper for the suspension of B class vehicles. This methodology was inspired by a previous work which has been applied successfully for the development of an eddy current (EC) damper used for the same type of applications. It is based on a multifield finite element coupled model that can be used to fulfil the electromagnetic, thermal, and fluid dynamic field properties and boundary conditions of a REC damper, as well as its non-linear material properties and boundary conditions, while also analysing its damping performance. The proposed REC damper features a variable fail-safe damping force, while electric power is advantageously regenerated at high suspension frequencies. Its damping performance has been benchmarked against that of a regular hydraulic shock absorber (selected as a reference) by analysing the dynamic behaviour of both systems using a quarter car suspension model. The results are expressed in terms of damping force, harvested power, thermal field, comfort and handling, with reference to ISO-class roads. The optimisation analysis of the REC damper has suggested useful guidelines for the harmonisation of damping and regenerative power performances during service operation at different piston speeds.

Parametric synthesis of car suspension

Problem. When driving a vehicle with comfortable suspension settings, there is a high probability that such adjustments may, firstly, cause discomfort to the driver and passengers, and secondly, when cornering, there is a high probability that the vehicle will overturn. A stiffer suspension leads to discomfort when driving on bumps. To choose the optimal parameters of the car's suspension, it is necessary to take into account the various parameters of the car's suspension, its settings and the features of the road surface. Goal. Solving the problem of choosing the values of the varied parameters of the car suspension - the coefficients of stiffness of the elastic elements and the average values of the damping coefficients of the shock absorbers, which provide a comfortable state of the driver and passengers while driving. Methodology. The approaches adopted in the work to solve the problems are based on the algorithmic method of parametric synthesis of dynamic systems. Results. The obtained maximum values of generalized coordinates, speeds and accelerations of the sprung part of the car body, as well as the minimum values of functionalities, with the help of ratios are possible to estimate the values of weights of additive functionality based on MathCAD software package. With the help of the algorithmic method of solving the problem of parametric synthesis of a dynamic system it is possible to it automate. Analysis of the process with the specified coefficients allows to detect high efficiency of damping of vertical oscillations of the under-sprung part of the car body. The amplitude of the linear displacement of the center of mass of the body does not exceed 0,02 m, and the amplitude of the generalized veloc-ity of the centre of mass of the sprung part of the housing does not exceed 0,08 m/s-1. Originality. The obtained parameters allow to minimize the time for selection of average values when designing the vehicle suspension. Practical value. The results can be recommended when studying the design features of vehicle suspensions. Thanks to the optimization of the MATLAB software package, modeling with different suspension parameters is possible.

Managing the Handling-Comfort Trade-Off of a Quarter Car Suspension System using Active Disturbance Rejection Control and Vyshnegradsky Equation

In this paper, we tackle the handling-comfort conflicting problem of a quarter-car system using Active Disturbance Rejection Control (ADRC). ADRC parameters are tuned using Vyshnegradsky equations which determine the stability criteria of a third order system. To do this, a multi-objective optimization procedure for selection of ADRC observer coefficients is formulated using a genetic algorithm. Suspension deflection and sprung mass acceleration responses are tested to a random road disturbance input. Simulation results show that the compromised solution between handling and comfort can be achieved by introducing the sprung mass acceleration into the feedback loop of ADRC. Using this approach allows for improving the issue of comfort up to 50 percent with just 10 percent worse performance of the issue of handling.

The estimation of frequency response of nonlinear quarter car model and bilinear model of damper characteristics

The paper presents proposed and tested methods of estimation of frequency response of nonlinear quarter car suspension model and comparison with method for linear model used for research of vehicle vertical dynamics. Linear quarter car suspension model is widely used for estimation of comfort and safety performance of passive and semiactive suspensions. The real suspension - especially shock absorbers - are non-linear in three aspects: static characteristics, hysteresis and the presence of friction. Testing linear suspension model is possible with the use of analytical transfer function formulas but testing real suspension on a testing stand or even virtual but nonlinear suspension needs to use methods of transfer function estimation. It was necessary to design appropriate input signal allowing to get useful response signals. With the use of obtained frequency responses a method of linear estimation of nonlinear suspension for a given range of working condition was proposed. Also the bilinear model of damper characteristic estimation was proposed and tested proving to be good alternative to nonlinear characteristic.

LIDAR BASED ACTIVE SUSPENSION

A car's suspension system is the device that physically separates the vehicle's body from its wheels. Traditional suspension systems have a limited ability to protect the car's chassis from the outside elements. Recent developments in this area go by the label of "active suspensions". As vehicle capabilities have risen, the suspension system's performance has significantly improved. Active suspensions are effective but by no means flawless. There are several things that can be done to make them better. Herein is the significance of this research paper. Using sensors like global navigation satellite systems (GNSSs), light detection and ranging (LiDAR), and inertial measurement units, autonomous cars are able to localize accurately and perceive real-time route information (IMUs). Using route information, cars may automatically go to a certain location without causing any traffic incidents. The majority of research on autonomous cars, although being an important reference for vehicles travelling on uneven terrain, has given little attention to information on road profiles. The precision and stability of data collected by LiDAR and IMUs are decreased by the strong vibrations that the majority of vehicles encounter when travelling over uneven terrain. On the other side, active suspension systems enable vehicles to retain stability on inclines, further ensuring sensor accuracy. In this article, we present a brand-new approach to estimating road profiles that makes use of active suspension systems on automobiles and LiDAR. In the former, an elevation map was supplemented with real-time cloud data points that were collected using 3D laser scanners, IMU, and GPS. In the latter, a Kalman filter method was used to further analyze the elevation map and fuse several cloud data points at a single map cell. The active suspension system is intended to be controlled using the model predictive control (MPC) approach in order to maintain vehicle stability and further lessen drifts of LiDAR and IMU data. The trial findings showed that the proposed approach was accurate and efficient when used in outdoor settings.

Application of modelling and simulation to evaluate the theta method used in diagnostics of automotive shock absorbers

The dynamic properties of the car's suspension largely depend on the damping that results from the state of the shock absorbers. Their technical condition is essential for vehicle occupants’ comfort and traffic safety. It changes with the time and intensity of use of the vehicle. Therefore, adequate methods of non-destructive (diagnostic) testing of suspension damping have been sought for many years. The on-vehicle tests are particularly useful thanks to their low cost and short test duration time. The newest method is the ‘theta’ method which is the subject of the presented article. Notation ‘theta’ usually means relative damping (damping ratio) in the vibrating system. The paper asses four variants of the method. Two versions come from modal analysis and are also known as the ‘peak-picking method’ or ‘half-power method’. Two other versions are described in cited patent documentations. Three linear ‘quarter car' models with their description in the frequency domain were used to assess mentioned variants of the ‘theta’ method. Calculations were made for two typical datasets corresponding to the front and rear suspension system of a medium-class motor car. This provided grounds for general qualitative and (within a limited scope) quantitative assessment of the usefulness of individual variants of the method under analysis and for comparisons between them. The paper is to help in choosing the variant of the ‘theta’ method that would most likely find the application and that might be recommended to manufacturers and would-be purchasers of diagnostic suspension testers. The author has also highlighted the importance of possible further research.

Modeling, analysis and PID controller implementation on suspension system for quarter vehicle model

The aim of this research is to acquire a mathematical model for the quarter vehicle model's passive and active suspension system and to build an active and passive suspension control for a quarter-vehicle model. The passive design of the suspension scheme is a compromise between vehicle handling capacity and passenger ride comfort. Passive suspension provides one of these two circumstances that conflict. Current car suspension systems use passive components only by using a coefficient of spring and damping with a fixed coefficient and two degrees of freedom. In the design and manufacture of cars, passenger comfort is a very significant parameter. The objective of the active suspension system is to enhance both the comfort of the ride and the handling of the highway by directly regulating the actuators of suspension power. In the active suspension system, the Proportional Integral Differential Controller (PID) method is applied. Various kinds of highway profiles and controllers such as P, PD, PI, and PID controllers evaluate the efficiency of the active suspension system comparing it with passive suspension scheme. This efficiency will be determined by using the MATLAB and SIMULINK to perform computer simulations.

Optimization of automobile active suspension system using minimal order

<p><span>This paper presents an analysis and design of linear quadratic regulator for reduced order full car suspension model incorporating the dynamics of the actuator to improve system performance, aims at benefiting: Ride comfort, long life of vehicle, and stability of vehicle. Vehicle’s road holding or handling and braking for good active safety and driving pleasure, and keeping vehicle occupants comfortable and reasonably well isolated from road noise, bumps, and vibrations are become a key research area conducted by many researchers around the globe. Different researchers were tested effectiveness of different controllers for different vehicle model without considering the actuator dynamics. In this paper full vehicle model was reduced to a minimal order using minimal realization technique. The entire system responses were simulated in MATLAB/Simulink environment. The effectiveness of linear quadratic regulator controller was compared for the system model with and without actuator dynamics for different road profiles. The simulation results were indicated that percentage reduction in the peak value of vertical and horizontal velocity for the linear quadratic regulator with actuator dynamics relative to linear quadratic regulator without actuator dynamics was 28.57%. Overall simulation results were demonstrated that proposed control scheme has able to improve the effectiveness of the car model for both ride comfort and stability.</span></p>

Series Active Variable Geometry Suspension: Full-Car Prototyping and Road Testing

In this article, a full-car prototype of the recently proposed mechatronic suspension, series active variable geometry suspension (SAVGS), is developed for the on-road driving experimental proof of concept, aiming to be adopted by suspension original equipment manufacturers as an alternative solution to fully active suspensions. Particularly, mechanical modifications are performed to both corners of the front double-wishbone suspension of a production car with active single link attached to the upper ends of the spring–damper units, while both corners of the rear suspension remain in the original (passive) configurations. The mechanical modifications involve innovatively designed parts to enable the desired suspension performance improvements while maintaining ride harshness at the conventional levels. A real-time embedded system is further developed to primarily implement power supply, data acquisition, and measurements of the vehicle dynamics-related variables, and robust control application for the ride comfort and road holding enhancement, which is based on a derived linearized model of the full-car dynamics and a newly synthesized H-infinity control scheme. The results obtained from the on-road driving experiments are in essential agreement with numerical simulation results also produced. Overall, the full-car prototype of SAVGS demonstrates promising suspension performance with an average 3 dB attenuation (or equivalently 30% reduction) of the chassis vertical acceleration at around the human-sensitive frequencies (2–5 Hz), as compared with the original vehicle with the passive suspension system. More importantly, the prototype also indicates the practicality of the solution, as the SAVGS retrofit to a real car is achieved by simple mechanical modifications, compact actuator packaging, small mass increment (21.5 kg increase with respect to the original vehicle), limited power usage (an average value of 134 W in dc batteries with a Class D random road), and acceptable economic cost.

Smelting high purity 55SiCr automobile suspension spring steel with different refractories

Abstract We performed a laboratory investigation at 1,873 K using a MoSi2 furnace to study the effect of refractories on inclusions in 55SiCr suspension spring steel. Three types of crucible materials (Al2O3, MgO·Al2O3, and MgO–CaO) were investigated. The results of this study indicated that SiO2, Al2O3, and MgO·Al2O3 were not suitable for making 55SiCr suspension spring steel. By contrast, MgO–CaO was a perfect choice for producing 55SiCr suspension spring steel. The advantages of using MgO–CaO crucibles to smelt 55SiCr spring steel were summarized in three aspects as follows: (i) the stability of MgO–CaO was quite good; (ii) a MgO–CaO crucible could act as a desulfurizer and dephosphorizer; (iii) finally, a MgO–CaO crucible could simultaneously remove Al2O3 inclusions.

Analysis of shock absorber resistance impact on load safety, continuous wheel rolling and energy loss in vehicle suspension

Introduction. The purpose of the article is to consider the effect of damping in the shock absorber on smooth running, continuous rolling of the wheel and energy loss in the suspension of the car.Materials and methods. The review is based on the analysis of the amplitude-frequency characteristics of a two-mass car model and the dependence of the shock absorber operation during the oscillation cycle on the frequency of kinematic action.Results. The article presents a calculation scheme and equations of dynamics of a two-mass oscillatory system equivalent to an automobile suspension. The frequencies at which the amplitude-frequency characteristics intersect for different levels of damping (invariant points) in a two-mass oscillatory system are calculated. The relative operation of the shock absorber for the oscillation cycle concept is proposed and a formula for calculating the relative operation of the shock absorber in a two-mass oscillatory system is given. A comparative analysis of graphs characterizing smooth running, continuous rolling of the wheel and energy losses in the suspension is carried out.Discussion and conclusions. It is revealed that significant contradictions between these requirements arise only near the second resonance of the sprung mass, with an increase in the frequency of vibrations in the resonant zone, these contradictions are decrease.

Modal vibration decomposition method and its application on multi-mode vibration control of high-speed railway car bodies

The vibration of a railway car body is a superposition of the vibrations of its various modes. It is typically easy to obtain the physical vibration of the car body using sensors in an in situ or a simulated test vehicle. However, it is difficult to determine the modal vibration of the body and its contribution. There are no effective multi-mode vibration control methods for the car bodies. This study proposes a modal vibration decomposition method (MVDM) based on singular value decomposition (SVD) and least squares fitting (LSF). Accordingly, the physical vibration of a railway car body is decomposed into modal vibrations. A method for calculating the modal contribution factor (MCF) is presented, and the dominant flexible modes of the car body are determined and considered the target for the vibration control method. Several pieces of equipment are considered as dynamic vibration absorbers (DVAs) to control the multi-mode vibration of the car body using the dynamic vibration absorption theory and determine the installation parameters of the individual equipment. Finally, the effectiveness of vibration control is verified through dynamic simulations. The results demonstrate the effective decomposition of the physical vibration of the car body into various modal vibrations using the MVDM. This provides accurate data for the MCF calculation and determination of the flexible modes of the car body. The proposed method reduces the vibration of the target modes and improves the ride quality of the railway vehicle. At the optimal damping ratio, the vibration of the DVA-based equipment itself is acceptable. This allows for multi-mode vibration control without requiring extensive modification to the car body structure or suspension system parameters of the vehicle.

Multi-body modelling and ride comfort analysis of a seated occupant under whole-body vibration

Seated occupants of any on/off-road vehicle are continuously exposed to undue low-frequency mechanical whole-body vibration (WBV) owing to the vibration conveyed from seat and backrest because occupants need to compromise with comfort and safety, leading to several musculoskeletal disorders and injuries in the body. Pain in the lumbar region is one of the most common problems that develop because of force transmitted from the backrest. Thus, consideration of backrest is highly essential while developing a biomechanical model for ride comfort analysis. For this purpose, a 20 degrees-of-freedom (dofs) biomechanical model has been proposed with a backrest to analyse cross-coupled segmental transmissibility. The interconnection between different segments of mass and backrest are modelled using eight linearized (direct as well as cross-coupled) stiffness and damping parameters. Biomechanical model parameters are estimated and optimized through a multi-objective firefly algorithm by minimizing the sum of squares error difference between analytical results and experimental segmental transmissibility published in the literature. Subsequently, ride comfort analysis is performed by integrating the proposed model with 7-dofs passenger car model. For different body segments, simulated results are obtained in terms of vertical accelerations and compared with ride comfort standards as per ISO 2631-1:1997. Additionally, a sensitivity analysis (±20% variation in mass, stiffness and damping) is performed to enhance the ride comfort of the occupant. The findings suggest that designers must focus on the pelvis, lower and upper back regions to improve the ride comfort of the occupants. The concepts and ideas outlined in this article are directly applicable in making human dummies, car suspension and seat design in the industry.