Strut Suspension Research Articles

Evaluation of reliability indicators of shock absorbers struts of M1 category cars in conditions of violation of established market relations between end users of spare parts and suppliers

Introduction. Over the past two years, there has been a violation of established market relations between end users of spare parts and suppliers. This led, on the one hand, to a significant increase in the cost of automotive components, and, on the other, to a reorientation of the market to new alternative manufacturers and suppliers. The main purpose of the work was a statistical assessment of the reliability indicators of the most expensive suspension element – the McPherson suspension strut, in the conditions of replacing the original struts with analogues available on the market.Methods. The study of the operational reliability of systems, components and assemblies of M1 cars was conducted in a dealership during 2022-2023. The study mainly involved cars with a sedan body and a McPherson front suspension. At the same time, the reason for contacting the service, the mileage of the car, as well as the types of work performed were recorded in each work order. The experimental data were processed using MSExcel and MatLab software from MathWorks.Resultsand conclusions. The conducted research allowed us to conclude that the appeals on the suspension of the car are almost twice as high as other appeals. The most expensive elements – the front shock struts, account for up to a third of all suspension failures. To assess the reliability indicators of alternative racks, the failure distribution law (normal), the probability of failure and uptime are determined, and the parameters of the distribution law are determined: mathematical expectation, standard deviation and coefficient of variation. It was found that the resource of the rear shock absorbers is at least 30% more, and there are significantly fewer calls at the service station. Thus, the operation of a car with racks from alternative manufacturers is quite reasonable, despite the fact that the resource of racks from alternative manufacturers is usually lower than that of the original brands.

The influence of the anti-roll bar on the vehicle’s roll angle

This study investigates the impact of the anti-roll bar (ARB) on the roll angle of a Toyota Prius vehicle. The vehicle is equipped with a front independent MacPherson strut suspension incorporating a P-shaped stabilizer bar, and a rear semiindependent torsion beam suspension. The methodology involves determining the stiffness of the ARB and analyzing its influence on the vehicle’s roll angle using both theoretical and experimental approaches. The results indicate that the mathematical model, which takes into account the stiffness of the stabilizer bar, effectively predicts and explains the vehicle’s roll behavior. Keywords: unsprung mass displacement, vehicle stability, anti-roll bar

Topology optimization of a MacPherson control arm

One of the most important systems in ground vehicles is the suspension system, which is responsible for the ride comfort, the road holding and handling. A crucial part of a passenger car passive suspension system is the control arm or wishbone arm or A-arm. Its main function is to provide a link between the body of the vehicle and the wheels. In this paper, the studied control arm is a part of a MacPherson strut suspension and its dimensions correspond to a front right suspension of a SUV vehicle. Two geometrical models of the control arm were developed in Solidworks® CAD-CAE Software, one with the measured dimensions and one with the outline dimensions of the control arm. A finite element model of the first one was built, using typical loading conditions, in order to determine the deformation and the stress contours. Then a topology optimization analysis was carried out to the second one in order to obtain a new design for the control arm. The FE results of the existing control arm and the optimized one were compared in terms of weight and structural integrity in different loading conditions leading to conclusions regarding the optimization procedure.

Experimental modelling and analysis of compact hydro-pneumatic interconnected suspension strut considering pneumatic thermodynamics and hydraulic inertial properties

Hysteresis properties exist in the Hydro-pneumatic interconnected suspension (HIS) system, which are mainly related to the gas state, inertial of hydraulic fluid in the long connection pipes and friction properties. The available model is normally simplified based on the ideal gas state equation and no hydraulic inertial assumption, and then cannot describe the dynamic properties of HIS strut accurately, which restricts the better application of HIS in different areas. In this study, the mathematical model of one kind of compact HIS strut integrating the gas chamber within the strut piston rod are proposed. The proposed model considers the gas state model described by ideal gas law with Energy Equation and the fluid inertial properties combined with laminar flow model across the connection pipes and seal frictions described by hyperbolic tangential hysteresis friction model, in which all the model parameters are identified through extensive experimental data. The validity of the proposed model has been verified through experimental under in-phase and out-of-phase harmonic excitations with different amplitudes and frequencies. The results show that the established model can not only describe the fundamental properties (force–displacement/velocity) with good accuracy, but predict the hysteresis phenomenon and frequency dependency property associated with both the gas pressure–displacement characteristic related to the heat transfer and the pressure-flow rate property between connection pipes related to the inertial of fluid flow reasonably well. The result also reveals that the effect of fluid inertial to the dynamic properties of the HIS strut is significant, which may make the stiffness performance worse under both in-phase and out-of-phase excitations especially high frequency excitation signals.

Piezo impedance-based monitoring of loosening of bolts: Experimental and numerical study

The suspension strut mount plays a crucial role in any vehicular suspension system, where it acts as a connector (bolted) to the vehicular body and suspension strut. The mount’s purpose is to cushion the Vehicular impacts and reduce the jarring effect, noise, and vibration caused due to vehicle movement over the undulated roads. The self-loosening of bolts results because of the up and down impact of the spring cause the jounce bouncer to push and pull action at the mount interface, cause vibrations transmitted to the vehicle camber. Self-loosening leads to damage of mount followed by clunking noises, noisy steering, tire misalignment, and can cause discomfort to the passenger. Therefore, condition monitoring and assessment of an upper strut mount is necessary for vehicles. This paper studies the feasibility of the piezo Impedance-based Structural health monitoring (SHM) technique to monitor the self-loosening bolts in the upper strut mount of the suspension system (MacPherson strut suspension) of passenger car. The piezo coupled signatures were obtained experimentally by loosening all the three bolts (connected to strut bearing) through control torques through a digital torque wrench. All the experimental signatures were acquired with a single PZT patch bonded to the surface of the upper strut mount for loosening bolts with pre-tight loss. Progressive damage scenarios are simulated along with preload loss of either single bolt or all three bolts, respectively. Three different statistical damage indices were evaluated for damage quantification raised due to bolt loosening. A 3D numerical modeling of strut mount is done using ANSYS WORKBENCH, and piezo impedance signatures were acquired (hence converted to admittance) for validating the experimental signatures. In an overall, this study provides an insight into the loss of structural integrity due to the self-loosening of suspension bolts, which can be threatful to vehicular integrity.

Design of end coil angular position and centerline shape of C-type side load coil spring for reducing side load of MacPherson strut suspension

MacPherson strut suspension, which is widely used vehicle suspension type, decreases the riding comfort and durability of strut module due to the side load generated at the damper. In this study, a method for designing a C-type side load coil spring is proposed to reduce the side load, considering not only the centerline shape, but also the end coil angular position of the spring. The effect of end coil angular position as well as centerline shape on the force axis are analyzed through finite element analysis (FEA) and regression analysis. Formulas are established based on the analyses and the C-type coil spring was designed considering the effects of both design variables on the force axis. Then, the side load of the MacPherson strut suspension on which the designed C-type side load coil spring was mounted was calculated by using the flexible multibody dynamic analysis method. Finally, a side load reduction effect of C-type side load coil spring is analyzed by comparing with that of helical-type coil spring.

Performance Analysis of Helical Compression spring And Banana or C Shaped Coil Spring Under Various Loading Conditions

Suspension system is one of the major and indispensable subsystems for land vehicles and has functions of providing better road holding, handling, and ride comfort. There are many suspension system types used for automobiles, and MacPherson strut suspension is one of the most widely used suspension system type due to its favorable features like simplicity, low cost, and high performance. However, there exists a drawback of this suspension type; since the coil springs have no ability to absorb lateral forces, undesired dry friction effects on the damper may degrade the ride comfort. As remedy to this drawback, the most popular and contemporary application is the use of coil spring forms which are called side load springs.It is observed that, the vehicle drifts towards one side due to high weight of suspension system. This problem can be solved by implementation of banana-C shaped coil spring. A banana,C-shaped coil spring is designed in such a way that it, when fitted correctly, exerts an opposing force compensating for the aforementioned side load pressure. This creates a balance and leads to the best possible working conditions for the shock absorber, ensuring a longer lifetime. Creo software was utilized to design the helical compression spring. The static analysis using finite element method has been done in order to find out the detailed load vs. defection of the helical compression spring and banana-shaped coilspring.

Design and Analysis of Suspension Strut in Automobile Vehicles

This research paper discusses about the design and analysis of suspension strut used in automotive industries. The main objective of this research is to study the suspension strut by modelling using solid works and then analysis have been performed using ANSYS by considering structural steel, carbon fiber and E-Glass material. Based on the results obtained from the analysis, comparison have been made for above materials to reduce the weight of the suspension strut to improve the life of the model. From the analysis results it can be concluded that it is possible to reduce the weight of suspension strut using composite materials. From the above study it can be concluded that glass fiber has performed well as compared to other materials which in turn increases the life of the suspension strut.

Active Vehicle Suspension with Anti-Roll System Based on Advanced Sliding Mode Controller

In the paper authors consider the active suspension of the wheeled vehicle. The proposed controller consists of a sliding mode controller used to roll reduction and linear regulators with quadratic performance index (LQRs) for struts control was shown. The energy consumption optimization was taken into account at the stage of strut controllers synthesis. The studied system is half of the active vehicle suspension using hydraulic actuators to increase the ride comfort and keeping safety. Instead of installing additional actuators in the form of active anti-roll bars, it has been decided to expand the active suspension control algorithm by adding extra functionality that accounts for the roll. The suggested algorithm synthesis method is based on the object decomposition into two subsystems whose controllers can be synthesized separately. Individual suspension struts are controlled by actuators that use the controllers whose parameters have been calculated with the LQR method. The mathematical model of the actuator applied in the work takes into account its nonlinear nature and the dynamics of the servovalve. The simulation tests of the built active suspension control system have been performed. In the proposed solution, the vertical displacements caused by uneven road surface are reduced by controllers related directly to suspension strut actuators.

다물체 동역학 해석을 통한 맥퍼슨 스트럿 서스펜션 사이드 로드 스프링의 승차감 개선 효과 분석

맥퍼슨 스트럿 서스펜션에 적용되는 사이드 로드 스프링을 해석하기 위해서는 일반적으로 비선형 유한요소 해석이 사용된다. 그러나 비선형 유한요소 해석은 모델링 및 해석에 많은 시간이 소요되는 경우가 많다. 본 논문에서는 절대절점좌표계를 이용하여 비선형 유한 요소를 모델링하고, 이를 다물체 동역학 모델에 적용하여 해석하는 방법을 설명한다. 그리고 하중을 받지 않은 상태로 설계된 사이드 로드스프링을 차량에 장착된 상태로 전환하기 위한 지그 모델을 구성하는 방법을 제시하고, 이 결과를 반차량 및 전차량 모델에 적용하여 다물체 동역학 해석을 수행한다. 이러한 해석들을 통하여, 기존의 유한요소 해석을 통해서는 구현하기 힘들거나 시간이 많이 걸리는 사이드 로드 스프링의 효과 분석을 보다 쉽고 빠르게 수행할 수 있다.

Failure study as a physical component in mechanical suspensions of two automobile models of an automotive company

Car suspensions are a key element for the good behavior of cars. There are many types with their advantages and disadvantages, but among them, the most used and known today is the MacPherson strut suspension. The MacPherson strut is a system devised by Earle S. MacPherson in the 40s and patented by Ford in 1953, which today is used for the front axle of most cars. This type of suspension is very versatile because it can be used on the rear as well as front axles, and because of its low cost. These types of vehicles present many breakdowns on these pieces in the municipality of “Ocaña, Norte de Santander, Colombia” since the type of terrain is very complex (steep slopes, poor condition of the roads, among others), which leads to breakdowns on the pieces due to shear stresses, which could cause a traffic accident and high repair costs. This work seeks to show the identification of the vehicles that use the MacPherson strut and its possible failures. Subsequently, the analysis of the stresses on the lower arm system of the MacPherson strut is carried out in compact cars using simulation software. to perform the physical analysis behavior.

Design and experimental modeling of a compact hydro-pneumatic suspension strut

The dynamic properties of a compact hydro-pneumatic suspension strut integrating the gas chamber are investigated analytically and experimentally. A comprehensive experiment was designed to experimentally characterize the dependence of friction force on the strut operating pressure in addition to the pressure/force–displacement and pressure/force–velocity properties of the prototype under broad ranges of excitations. An analytical model of the strut is formulated to incorporate the polytropic gas process, nonlinear and hysteretic friction force and turbulent flows across the piston orifices. Owing to dominant effect of friction due to seals of the floating piston separating the gas and oil media, and strong dependence of friction force on the operating pressure, the Coulomb and Stribeck friction effects are described by a nonlinear function in the operating pressure. Furthermore, the viscoelastic O-ring-type seals contributed to notable hysteresis at very low velocities, which is described by a hyperbolic tangent function in velocity. The discharge coefficient of flows through orifices is also identified from the measured fluid pressures. The validity of the proposed model is demonstrated through comparisons of force–displacement and force–velocity responses of the model with the corresponding measured data under broad ranges of excitations. The comparisons revealed that the model could predict dynamic behavior of the strut reasonably well. The effects of charge pressure and gas volume are further investigated to seek guidance on tuning of the strut for realizing desired load carrying capacity and suspension stiffness.

A Comparative Study On McPherson Strut Suspension System And Double Wishbone Suspension System

Now a days, the two most commonly used suspension system in automobiles are the McPherson Strut uspension System and Double Wishbone Suspension System. A vehicle is provided with the suspension system in order to provide a comfortable ride to the passengers and to avoid additional stresses in the vehicle frame. This paper contains the comparative study between McPherson Strut Suspension System and Double Wishbone Suspension System. The comparison is obtained by considering various parameters like Basic differences of the system their Geometry, Kinematic Analysis, ANSYS Simulation which includes structural analysis with static and dynamic loading, Graphical representation of Wheel position vs Camber.

Hydraulic damping nonlinearity of a compact hydro-pneumatic suspension considering gas-oil emulsion

Hydro-pneumatic suspension (HPS) systems could attenuate broad-frequency-range vibration mainly via the nonlinear hydraulic damping property. While the strut design with shared gas-oil chamber leads to gas-oil emulsion within strut chambers which intricately affects the fluid flows between the coupled chambers and thus the damping force. This study investigated the temperature- and frequency-dependent hydraulic damping properties of a compact hydro-pneumatic suspension strut, in terms of the flow discharge coefficients. A laboratory experiment was performed at nearly-constant strut temperature of 30, 40 and 50 °C, in the frequency range of 0.5-8 Hz. The obtained experimental data are used to identify the discharge coefficients of the emulsion flow across bleed orifices and check valves, which determine the damping property of the considered strut. An analytical model is established, and the simulation results obtained under different strut temperature and excitation frequencies showed reasonably good agreements with the experimental data. The results suggested greater discharge coefficient of the bleed orifice than that of the check valve, which might be due to the relatively complex structure of the check valves. Greater excitation frequency was shown to decrease the discharge coefficients in a nonlinear manner, irrespective of the strut temperature. Greater strut temperature, however, leaded to greater discharge coefficient of the check valve. Increasing the excitation frequency from 0.5 Hz to 8 Hz resulted in nearly 14 % decrease in the discharge coefficient of check valve at a constant strut temperature of 50 °C.

Ride comfort enhancement for passenger vehicles using the structure-immittance approach

This paper presents a novel approach to identify inerter-based suspension struts, which can provide significant performance enhancement for passenger vehicles. The inerter has been used on Formula 1 racing cars, and several beneficial devices incorporating inerters have also been identified for ride comfort enhancement. However, previous investigations either were limited to simple network configurations with moderate performance improvement, or resulted in complicated configurations with a large number of elements which are impractical for real-life applications. In addition, some important practical performance constraints have not been taken into consideration, such as high-frequency dynamic stiffness which influences the NVH performance, and frequency content consideration of the sprung mass acceleration which more directly relates to passenger perception. In this paper, a quarter-car model including top mount is studied, with the performance of a conventional suspension strut presented as baseline. The structure-immittance approach, which can cover all networks with pre-determined numbers of each element type, is adopted for the identification of the optimal suspension configurations. Several configurations with up to a performance improvement are identified with all other practical performance indices to be no worse than the baseline. The suspension devices proposed in previous works are also considered for a sake of comparison, demonstrating significant advantages of the structure-immittance approach. Subsequently, a sensitivity analysis against the sprung and unsprung mass changes is carried out, which represents cargo and tyre weight variations, respectively. Time domain response and other reality checks are then conducted for the out-performing configurations, which reconfirm the ride comfort enhancement and ensure no unexpected behaviour occurs.

Transient Dynamic Analysis of Vehicle Brake Creep Groan

Brake creep groan is getting more and more attention in vehicle brake design and development. However, many complex motions of brake creep groan have not been comprehensively, which are critical for the understanding and prevention of the problem. In this paper, brake creep groan dynamics are studied and analysed to research the mechanisms of creep groan. Vehicle road experiments on a slope road are performed to record creep groans using two tri-axial accelerometers, which are install at the caliper and suspension strut. History curves of oil pressure and caliper accelerations, time–frequency spectrogram of the vibrations, and largest Lyapunov exponent are calculated using Hilbert–Huang transform and empirical mode decomposition methods. This study reveals that the sources of the brake creep groan include unstable sliding in addition to transient and steady-state motions of stick–slip between disc and pad. It is found that one of the important sources of the creep groan is the unstable sliding, which has impulsive and discontinuous nature and has effects of hammering leading to strong excitation and wideband vibrations. It is also found that when creep groan occurs, multiple modes of the brake system and subsystems contribute to the complex vibrations. The existences and the properties of the stable, unstable, and chaotic vibrations associated with the creep groan are characterized, which depend on the system natures, excitations, and tribological conditions.

Kinematic and Dynamic Analysis for a New MacPherson Strut Suspension System

Abstract The present paper undertakes kinematic and dynamic analysis of front suspension system. The investigated model is a full-scale Macpherson which is a multibody system. Two degree of freedom model is considered here to illustrate the vertical displacement of sprung mass and unsprung mass with using displacement matrix. Ride and handling parameters including displacement of sprung and unsprung masses, camber/caster angle, and track changes are derived from the relationships. Moreover, geometrical model and equations are validated by Adams/Car software. The kinematic and dynamic results have been compared in both analytical and numerical outputs for verification. The proposed analytical model shows less than 5% differences with a complicated multibody model.

Quantification of Uncertainty in the Mathematical Modelling of a Multivariable Suspension Strut Using Bayesian Interval Hypothesis-Based Approach

Mathematical models of a suspension strut such as an aircraft landing gear are utilized by engineers in order to predict its dynamic response under different boundary conditions. The prediction of the dynamic response, for example the external loads, the stress and the strength as well as the maximum compression in the spring-damper component aids engineers in early decision making to ensure its structural reliability under various operational conditions. However, the prediction of the dynamic response is influenced by model uncertainty. As far as the model uncertainty is concerned, the prediction of the dynamic behavior via different mathematical models depends upon various factors such as the model's complexity in terms of the degrees of freedom, material and geometrical assumptions, their boundary conditions and the governing functional relations between the model input and output parameters. The latter can be linear or nonlinear, axiomatic or empiric, time variant or time-invariant. Hence, the uncertainty that arises in the prediction of the dynamic response of the resulting different mathematical models needs to be quantified with suitable validation metrics, especially when the system is under structural risk and failure assessment. In this contribution, the authors utilize the Bayesian interval hypothesis-based method to quantify the uncertainty in the mathematical models of the suspension strut.

Uncertainty quantification in the mathematical modelling of a suspension strut using Bayesian inference

Abstract In the field of structural engineering, mathematical models are utilized to predict the dynamic response of systems such as a suspension strut under different boundary and loading conditions. However, different mathematical models exist based on their governing functional relations between the model input and state output parameters. For example, the spring-damper component of a suspension strut is considered. Its mathematical model can be represented by linear, nonlinear, axiomatic or empiric relations resulting in different vibrational behaviour. The uncertainty that arises in the prediction of the dynamic response from the resulting different approaches in mathematical modelling may be quantified with Bayesian inference approach especially when the system is under structural risk and failure assessment. As the dynamic output of the suspension strut, the spring-damper compression and the spring-damper forces as well as the ground impact force are considered in this contribution that are taken as the criteria for uncertainty evaluation due to different functional relations of models. The system is excited by initial velocities that depend on a drop height of the suspension strut during drop tests. The suspension strut is a multi-variable system with the payload and the drop height as its varied input variables in this investigation. As a new approach, the authors present a way to adequately compare different models based on axiomatic or empiric assumptions of functional relations using the posterior probabilities of competing mathematical models. The posterior probabilities of different mathematical models are used as a metric to evaluate the model uncertainty of a suspension strut system with similar specifications as actual suspension struts in automotive or aerospace applications for decision making in early design stage. The posterior probabilities are estimated from the likelihood function, which is estimated from the cartesian vector distances between the predicted output and the experimental output.

Vibration Fatigue Analysis of Carbon Steel Coil Spring under Various Road Excitations

This paper presents the evaluation of frequency-based approach predicted spring using acceleration signals that were collected from various road conditions. Random loadings in the forms of acceleration are nominal and more flexible for vehicle components fatigue assessment. In this analysis, the strain time history of the spring and acceleration signals of the suspension strut was measured from three different road conditions. The acceleration signals were then transformed into power spectra density (PSD). PSD cycle counter, like Lalanne, Dirlik, and narrow band approach, was applied to obtain equivalent load cycles. The stress response was obtained through having the equivalent load cycles with a spring modal frequency response function (FRF) and different stress criterion, like absolute maximum principal and critical plane approaches. Then, the stress response was used to predict the spring fatigue life using stress-life (S-N) approach. The results revealed that the harshest road condition was the rural road where the spring with fatigue life of 4.47 × 107 blocks to failure was obtained. The strain predicted fatigue life was used to validate the frequency-based predictions using a conservative approach. It was found that the Dirlik approach has shown the closest results to the strain life approach, which suggested that the Dirlik approach could be used for spring fatigue life prediction with the acceptable accuracy.