Suspension Frame Research Articles

SHAPE OPTIMIZATION OF A TWO WHEELER SUSPENSION WITH DIFFERENT CROSS SECTIONS

The two-wheeler chassis consists of the frame, suspension, wheels and brakes. The chassis is what truly sets the overall style of the two-wheeler. Automotive chassis is the main carriage systems of a vehicle. The frame serves as a skeleton upon which parts like gearbox and engine are mounted. It can be made of steel, aluminum or an alloy. It keeps the wheels in line to maintain the handling of the two-wheeler.The frame of a motor vehicle supports all the drive assemblies, i.e. the engine, gearbox and axles (front and rear). In addition the suspension and steering systems and the shock absorbers are attached to it. The appropriate body is fixed to the chassis. It is essential that the frame should not buckle on uneven road surfaces and that any distortions which may occur should not be transmitted to the body. The frame must therefore be torsion−resistant. The frame of a motor vehicle is the load bearing part of the chassis which supports all forces (wheel forces) and weights. It should be as rigid as possible.The main aim of the project is to model a frame of a two wheeler using 3D modeling software Pro/Engineer. Two models of suspension are designed for pipe type and rectangular cross sections.Considering the frame as a beam, calculations are done to determine the displacement and stress by applying loads.To validate the strength of two models, Structural analysis is done by applying the wheel forces. In this analysis ultimate stress limit for the model is determined. Analysis is done for frame using two materials steel and aluminum to verify the best material for frame. Modal analysis is also done to determine natural frequencies of suspension frame. Analysis is done in ANSYS software.Comparison is done mathematically and by FEA analysis. And also we can validate the better cross section and material for suspension frame.

Modeling and Analysis of Suspension Frame of Maglev Train

Based on the acceleration feedback system, the vertical dynamic model of the low-speed maglev train is established. By decoupling the suspension frame module, the author conducted a stress analysis of the single-sided and the entire suspension system, and established a system dynamics model of the suspension frame. The suspension controller is designed using classic PD control and acceleration feedback control methods. Then, the author used Simulink to create a dynamic simulation analysis program to analyze the dynamic performance of the suspension system affected by track misalignment and external disturbance forces, and analyze the impact of the suspension frame’s parameter design on the suspension system performance.

Research on hardware-in-the-loop simulation of single point suspension system based on fuzzy PID

The stability control of maglev trains is one of the core problems in the research of maglev train technology and the realisation of this goal is of the great scientific value in the field of magnetic levitation. Based on this, the research on the suspension control strategy of single point maglev system is founded and the control strategy is verified by experiments on Magnetic Levitation Ball System (MLBS). Aiming at the structure of multi-group independent control system of maglev train suspension frame, in order to improve the overall stability control ability of the suspension frame, the coupling relationship between the subsystems is established by introducing the suspension response deviation compensator. Finally, the effect of single point suspension control system is discussed and the cooperative control of suspension frame is carried out on MATLAB. Simulation and analysis show that each subsystem has good anti-jamming ability and the suspension system realises the balanced and stable control under different interference signals, which provides a certain reference value for further study of maglev train suspension control.

Research on hardware-in-the-loop simulation of single point suspension system based on fuzzy PID

The stability control of maglev trains is one of the core problems in the research of maglev train technology and the realisation of this goal is of the great scientific value in the field of magnetic levitation. Based on this, the research on the suspension control strategy of single point maglev system is founded and the control strategy is verified by experiments on Magnetic Levitation Ball System (MLBS). Aiming at the structure of multi-group independent control system of maglev train suspension frame, in order to improve the overall stability control ability of the suspension frame, the coupling relationship between the subsystems is established by introducing the suspension response deviation compensator. Finally, the effect of single point suspension control system is discussed and the cooperative control of suspension frame is carried out on MATLAB. Simulation and analysis show that each subsystem has good anti-jamming ability and the suspension system realises the balanced and stable control under different interference signals, which provides a certain reference value for further study of maglev train suspension control.

Kinematics Modeling and Analysis of Mid-Low Speed Maglev Vehicle with Screw and Product of Exponential Theory

Maglev transportation is a new type of rail transit, whose vehicle is different from the two-bogie structure of the wheel-rail train. Generally, it consists of four to five suspension frames supporting a car body in parallel. The moving mechanism of a vehicle often consists of hundreds of moving parts, showing a multi-rigid body system in serial-parallel structure. At present, there is no theoretical framework for systematically and accurately describing the kinematics and dynamics of the Maglev train. The design work is at the level of simple equivalent estimation or measurement from the CAD drawing, which makes the system performance analysis and optimization work unable to be carried out scientifically. Based on the theoretical framework of screw theory and exponential mapping, the forward kinematics modeling, inverse kinematics solution, transition curve modeling and computational analysis methods for the Maglev train are proposed in this paper. A systematic and accurate theoretical framework is constructed for the modeling and analysis of the motion mechanism of the Maglev train, which makes the design and analysis of the Maglev train at the scientific level.

Design of New Energy-Efficient Permanent Magnetic Maglev Vehicle Suspension System

In view of the current traffic criticism faced by urban construction and the quality development and personalized trend of future rail transit system, a new type of maglev rail transit system is proposed in this paper. The principles of the modules of train suspension guidance, linear drive and on-board communication are also introduced and analyzed in this paper. Additionally, the feasibility of train suspension structure is studied based on Ansoft Maxwell finite element simulation, which includes: under three-dimensional magnetic field, the static magnetic force of Halbach permanent magnet array is changed, and the safety and reliability of the permanent magnet suspension array are verified by comparing with the actual test vehicle sampling data; the critical stability characteristics of suspension structure under static magnetic field are proved by physical modeling. Therefore, the electromagnetic damping structure is introduced into the vehicle suspension frame to constitute the hybrid suspension control system of permanent magnet electromagnetic, and the hybrid suspension model is established, which proves that the hybrid suspension system has controllable observability. Finally, the linearized state feedback control strategy is designed for the single-point electromagnetic levitation ball system to simulate the compensation and regulation of the static magnetic field by the electromagnetic damping system. The excellent performance of the electromagnetic levitation ball also proves the feasibility and rationality of the electromagnetic control strategy. Compared with the traditional electromagnetic hybrid suspension system, this system realizes “zero” power suspension, and the energy consumption of train suspension is only consumed in the instant that the electromagnetic damping system is regulated.

Two-Step Aging Behaviour of Solution Treated A356 System Alloy

Al-7mass%Si-0.3mass%Mg alloy is widely applied to the automotive components, such as road wheel or suspension frame because of having higher ductility and corrosion resistance. Two-step aging behavior of solution treated Al-7mass%Si-0.3mass%Mg system alloy A356 cast into permanent mold and solution treated was investigated by micro-vickers hardness measurement, optical microscopy (OM) and transmission electron microscopy (TEM). The microstructure of as-cast state was consist of primary crystallized α-Al and secondary crystallized eutectic phases. Al-7mass%Si-0.3mass%Mg alloy after casting, the test specimens were heat treated for different pre-aging temperatures at 273K, 348K and 423K for various times after solution treatment at 813K for 36ks. After pre-aging treatment, the test specimens were heat treated for artificial aging at 523K for various times. The peak hardness increased almost the same value when the pre-aging temperature was 273K. On the other hands, positive effect of the final-aging was occurred after pre-aging at 348K and 423K with significantly increasing hardness in the under-aging region. The fine precipitates were observed in the specimen which was final aging at 523K after pre-aging at 348K and 423K.Such a positive effect is considered due to the influence of precipitated phase mainly such as clusters and /or G.P.zone.The present study aims to investigate the effect of pre-aged temperature on final-aged behavior in A356 system alloy.

Coupling vibration analysis of full-vehicle vehicle-guideway for maglev train

ABSTRACTIn order to investigate the effect of inner loop current gain coefficient, time lag and levitation current perturbation on the static suspension stability for the maglev vehicle, a vertical vibration model of HSST-type maglev train with five suspension frames was established. The following conclusions are drawn based on the obtained results: for suppressing vehicle-guideway coupling vibration, the gain coefficient of the inner loop should take a large value in the double loop control, such as a value of 300. If one suspension controller has a large time constant delay, such as a value of 4 ms, and the suspension instability will occur for the vehicle. When the levitation current has a large range perturbation, such as a value of 50%, increasing the control frequency of the levitation controller can suppress the vehicle-guideway coupling vibration of the maglev system to a certain extent.

Module-based structure design of wheeled mobile robot

Abstract. This paper proposes an innovative and systematic approach for synthesizing mechanical structures of wheeled mobile robots. The principle and terminologies used for the proposed synthesis method are presented by adopting the concept of modular design, isomorphic and non-isomorphic, and set theory with its associated combinatorial mathematics. The modular-based innovative synthesis and design of wheeled robots were conducted at two levels. Firstly at the module level, by creative design and analysing the structures of classic wheeled robots, a wheel module set containing four types of wheel mechanisms, a suspension module set consisting of five types of suspension frames and a chassis module set composed of five types of rigid or articulated chassis were designed and generalized. Secondly at the synthesis level, two kinds of structure synthesis modes, namely the isomorphic-combination mode and the non-isomorphic combination mode were proposed to synthesize mechanical structures of wheeled robots; which led to 241 structures for wheeled mobile robots including 236 novel ones. Further, mathematical models and a software platform were developed to provide appropriate and intuitive tools for simulating and evaluating performance of the wheeled robots that were proposed in this paper. Eventually, physical prototypes of sample wheeled robots/rovers were developed and tested so as to prove and validate the principle and methodology presented in this paper.

Dynamic analysis of the interactions between a low-to-medium-speed maglev train and a bridge: Field test results of two typical bridges

The rated suspension gap of a low-to-medium-speed maglev train with electromagnetic suspension is normally 8–10 mm. However, while either passing over a bridge or being stationary on one, the maglev train deforms the bridge and therefore alters the suspension gap. Hence, a problem arises due to coupled vibrations between the maglev train and its supporting bridge. In the study reported here, field experiments were conducted on the Chinese Changsha maglev line, which was the first commercial low-to-medium-speed maglev line in China. The focus is on two types of pre-stressed double-track concrete bridges on the maglev line. One is a simply supported girder with a span of 25 m, while the other is a continuous girder designed as 25 + 35 + 25 m. The accelerations and vertical dynamic deflections of the two bridges at midspan were measured while a five-module low-to-medium-speed maglev train with electromagnetic suspension either passed over or was stationary on either bridge, as were the accelerations of the car body and the suspension frame. The basic dynamic characteristics of the two bridges are analysed and compared with those of bridges in various typical maglev lines. The vibration characteristics of the two bridges, the car body and the suspension frame are studied in the time and frequency domains for the maglev train running at normal speeds, low speeds and when stationary. The influences of the speed on the dynamic characteristics are discussed. Some comparisons with other studies are also carried out, including the effects of bridge parameters on the coupled vibrations and the running stability of a low-to-medium-speed maglev and a CRH2C wheel/rail train. Significant conclusions are drawn from the analysis: increasing the rigidity and mass of the bridge can significantly reduce its vibration; increasing the span and deflection of the bridge increases the vibrations of the car body and the suspension frame; the dynamics of the maglev vehicle and bridges are different when the maglev train runs at normal speeds (more than 30 km/h), low speeds (less than 30 km/h) and when being stationary. The running stability of a low-to-medium-speed maglev train is better than that of a CRH2C high-speed train. The present study provides a test basis for further research on the mechanisms for coupled vibrations of maglev train–bridge systems.

Dynamic characteristics analysis for a new-type maglev vehicle

A new type of walking mechanism for middle- and low-speed maglev vehicle, including a single anti-roll beam placed at the middle of each suspension frame, a big air spring placed at the middle of each longitudinal beam of each suspension module, and a forced steering mechanism canceled, was proposed to improve the comprehensive competitiveness of the middle- and low-speed maglev vehicle in the field of urban rail transit. The dynamic characteristics of a new-type maglev vehicle were investigated by dynamics simulation analysis. The following conclusions are drawn based on the obtained results: the new-type maglev vehicle meets the operational requirements at the running speed of 160 km/h on the straight line and at the running speed of 30 km/h on the curved track of radius 75 m.

Optimization of nonlinear quarter car suspension–seat–driver model

In this paper a nonlinear quarter car suspension–seat–driver model was implemented for optimum design. A nonlinear quarter car model comprising of quadratic tyre stiffness and cubic stiffness in suspension spring, frame, and seat cushion with 4 degrees of freedom (DoF) driver model was presented for optimization and analysis. Suspension system was aimed to optimize the comfort and health criterion comprising of Vibration Dose Value (VDV) at head, frequency weighted RMS head acceleration, crest factor, amplitude ratio of head RMS acceleration to seat RMS acceleration and amplitude ratio of upper torso RMS acceleration to seat RMS acceleration along with stability criterion comprising of suspension space deflection and dynamic tyre force. ISO 2631-1 standard was adopted to assess ride and health criterions. Suspension spring stiffness and damping and seat cushion stiffness and damping are the design variables. Non-dominated Sort Genetic Algorithm (NSGA-II) and Multi-Objective Particle Swarm Optimization – Crowding Distance (MOPSO-CD) algorithm are implemented for optimization. Simulation result shows that optimum design improves ride comfort and health criterion over classical design variables.

Fabrication and evaluation of a free molecule micro-resistojet with thick silicon dioxide insulation and suspension

A silicon free molecule micro-resistojet (FMMR) with a thermally insulating suspension frame composed of silicon dioxide has been designed, fabricated and tested. The concept was developed to increase the efficiency of FMMRs, especially in silicon-based integrated systems. Fabrication of the thick insulating frame was performed through oxidation of high-aspect ratio silicon trenches. The thermal properties of the 1 cm2 thruster were evaluated using an IR camera, and it was found that when the volume inside the frame is heated more than 200 °C using integrated nickel heaters, the temperature increase in the volume outside the frame is less than 50 °C. During operation in vacuum, the thrust range was calculated to be about 13–1070 µN and the maximum specific impulse 54 s. At maximum thrust, and a power consumption of 1.6 W, the total efficiency of the thruster was 17%. Designs of more efficient and versatile systems are discussed.

Repairing cartilage defects with bone marrow mesenchymal stem cells induced by CDMP and TGF-β1

The aim of this study was to explore the ability for chondrogenic differentiation of bone marrow mesenchymal stems cells (BMSCs) induced by either cartilage-derived morphogenetic protein 1 (CDMP-1) alone or in the presence of transforming growth factor-β1 (TGF-β1) in vivo and in vitro. BMSCs and poly-lactic acid/glycolic acid copolymer (PLGA) scaffold were analyzed for chondrogenic capacity induced by CDMP-1 and TGF-β1 in vivo and in vitro. Chondrogenic differentiation of BMSCs into chondrocytes using a high density pellet culture system was tested, whether they could be maintained in 3-D PLGA scaffold instead of pellet culture remains to be explored. Under the culture of high-density cell suspension and PLGA frame, BMSCs were observed the ability to repair cartilage defects by either CDMP-1 alone or in the presence of TGF-β1 in vitro. Then the cell-scaffold complex was implanted into animals for 4 and 8 weeks for in vivo test. The content of collagen type II and proteoglycan appeared to increase over time in the constructs of the induced groups (CDMP in the presence of TGF-β1), CDMP group and TGF group. However, the construct of the control group did not express them during the whole culture time. At 4 and 8 weeks, the collagen type II expression of the induced group was higher than the sum of TGF group and CDMP group by SSPS17.0 analysis. BMSCs and PLGA complex induced by CDMP-1 and TGF- β1 can repair cartilage defects more effectively than that induced by CDMP-1 or TGF-β1 only.

Aspectos fisiológicos do mountain biking competitivo

A prática do ciclismo off-road (mountain biking - MTB), cresceu muito nas últimas duas décadas, sendo incluído como esporte olímpico, nos Jogos de Atlanta em 1996, na modalidade Cross Country. Na última década, houve um aumento no número de publicações científicas que verificaram a demanda fisiológica durante competições, assim como o estudo de possíveis preditores da performance nesta modalidade. O objetivo deste estudo de revisão foi descrever alguns aspectos fisiológicos específicos do MTB Cross Country (MTB CC) competitivo (intensidade de provas, perfil fisiológico de atletas de elite, uso de suspensões e determinantes da performance em subidas). Observa-se na literatura analisada que as provas de MTB CC parecem impor uma sobrecarga fisiológica maior, quando analisada através da frequência cardíaca, do que provas de ciclismo de estrada com duração semelhante. Entretanto, quando analisada pela potência de pedalada, observa-se claramente a característica intermitente da modalidade, com variações de potência durante a prova entre zero e 500W, e potência média relativamente baixa em comparação aos valores de FC encontrados. Outro fator importante levantado neste estudo são as alterações fisiológicas decorrentes do uso de suspensões nas bicicletas de MTB CC. O uso deste equipamento reduz o estresse muscular provocado pelo terreno acidentado, embora pareça não afetar o gasto energético total, tanto em percurso plano como em subidas. Entretanto, é fato que o desempenho em circuitos acidentados é melhorado com o uso das suspensões. Com base nos estudos abordados nessa revisão, conclui-se que o MTB CC enquanto modalidade competitiva apresenta uma grande variação de intensidade (avaliada através da potência), sendo esta atribuída principalmente ao tipo de terreno (irregular e com muitas aclives e declives acentuados) em que as provas de MTB CC acontecem.

Prediction of fatigue life and estimation of its reliability on the parts of an air suspension system

Air suspension systems have been implemented in various commercial vehicles, such as buses and special purpose trucks, because of the comfortable ride and easy height control. An evaluation of the durability of vehicle parts has been required for service life and safety starting in the early stages of design. The cyclic load applied to the vehicle can cause fatigue failure of parts, such as the suspension frame. This paper presents a method to predict the fatigue life of the suspension frame at the design stage of the air suspension system used in a heavy-duty vehicle. To estimate the fatigue life using the SN method, the Dynamic Stress Time History (DSTH) is necessary for the part of interest. DSTH can be obtained from the results of the flexible body dynamic analysis using the Belgian road simulation and the Modal Stress Recovery (MSR) method. Furthermore, the reliability of the predicted fatigue life can be evaluated by considering the variations in material properties. The probability and distribution of the expected life cycle can be obtained using experimental design with a minimum number of simulations. The advantage of using statistical methods to evaluate the life cycle is the ability to predict replacement time and the probability of failure of mass-produced parts. This paper proposes a rapid and simple method that can be effectively applied to the design of vehicle parts.

A new support structure for independent wheel suspensions in heavy-duty trucks

Thyssen-Krupp Automotive Systems in Essen has presented an all-new support structure for independent suspensions in heavy-duty trucks. The system features innovative solutions for suspension mountings, frame structures and steering. It will improve handling characteristics and ride comfort and as well allow for future engine generations and emission demands.

Development of Suspension Frame of New Eight-wheel Lunar Rover

To improve the evenness of distribution of the mass of a complete rover on the wheels can improve the consistency of the driving power of rover driving motors,and to improve the passive adaptability of suspension frame on loose terrain can improve the stability and obstacle crossing capability of the rover.Therefore,topological structure synthesis of the suspension frame of eight-wheel lunar rover with passive adaptability to terrain is carried out,and two structural types of usable eight-wheel suspension frames are determined.Then simulation analysis is carried out for the two types of suspension frames in respect of simultaneously crossing vertical obstacle with wheels on the two sides,adaptability to curved terrain,and smoothness and stability of movement of rover body.On the basis of the analysis results,appropriate structural type of the suspension frame of eight-wheel rover is determined, and the composition and working principle of the movement system of that are expounded.ADAMS software is used to optimize the parameters of structure of suspension frame,on this basis structural design of suspension frame and differential mechanism is carried out,and principle prototype is manufactured.Tests of performances of the prototype are carried out in respect of grade climbing and obstacle crossing.The test results indicate that the distribution of load on the wheels is even and the adaptability to terrain is strong.It can climb onto loose sandy land with a slope of 22°and cross an obstacle of 200 mm high.

Buried objects detection and classification with a 3-D parametric sonar

This paper deals with a new sonar concept suitable for mine detection and classification in shallow and very shallow water. This concept is based on a 3-D high-resolution imaging information obtained from a 2-D scanning. Sediment penetration and narrow-beam constraint is made possible by the use of the parametric technique. A specific tool has been designed to be able to make a connection between a real operational configuration and experimental needs. A 2×2 m2 suspension frame has been built to allow the sonar displacement along the two axis direction. This suspension frame has been deployed first in a pool and then at sea above three different areas where mines and rocks had been buried. Experiments have been conducted in a shallow water area with the suspension frame mounted 2 m above the sea floor made of rough sand. Three-dimensional imaging techniques have been used to process the data and very good results have been obtained. Underwater mine and object detection and shape classification have been successfully demonstrated up to half a meter sediment burial. This paper shows these first results and describes sonar and signal characteristics and then discusses the data and image processing.

Body Weight Support Treadmill Gait Training in the Subacute Recovery Phase of Incomplete Spinal Cord Injury

Objectives: A pilot study was conducted on five patients with an incomplete spinal cord injury (iSCI) using a body weight support treadmill training (BWSTT) gait strat egy within the subacute phase of recovery. The objectives of this project were to de fine appropriate candidates, identify treatment parameters, select impairment and dis ability outcome measures, and solicit consumer input in preparation for a clinical efficacy trial.Methods: Five patients with injuries ranging from C2 lesion to T10 lesion con sented to participate and were within 2 months post injury. A commercially available mechanical suspension frame straddled a motorized treadmill, and a modified climber's harness was used for support. All participants were nonambulatory on entry into the study. The BWSTT intervention, consisting of 36 1-hour sessions over a 3-month period, was conducted by physical therapists and was customized to the patient's abil ities. Evaluations were conducted at baseline, at 6 weeks, and at the 12-week post- test interval. Clinical impairment measures included muscle strength, sensation, mus cle tone, perceived exertion, and treadmill training endurance. Gait analysis provided dynamic quantification of kinematic and surface electromyography (EMG) of five mus cles of the right lower limb on all participants on the BWS treadmill and three of the five patients during overground walking. A disability outcome measure was used to grade the level of ambulation function. A consumer team member conducted feed back interviews with participants to obtain their input to this research direction.Results: Lower limb unloading varied from 26 percent to 83 percent of body weight. All participants completed the 12-week training program and four individu als eventually progressed to overground walking. The fifth participant, who had the most severe motor impairments, did not achieve functional overground walking with out the aid of bilateral knee-ankle-foot orthoses. Improvements were evident in the clinical measures of strength, endurance, and percent BWS in four patients. Positive changes were recorded in temporal-spatial, joint motion, and EMG gait measures matching increased ambulation function in four of the five patients. Gait analysischanges in one patient were highlighted to illustrate dynamic measures of motor re covery. Consumer input and feedback from patients and therapists were positive and included suggestions for improvements.Conclusions: A multicenter randomized controlled trial is advocated to evaluate the efficacy of a BWSTT gait strategy in the subacute recovery phase of iSCI. This pilot work resulted in specific recommendations in the selection of candidates, the training and evaluation parameters, and the potential value of consumer input for fu ture research. Key Words: Incomplete spinal cord injury—Rehabilitation—Weight- supported treadmill gait training—Consumer input.