Suspension Configurations Research Articles

The Bridges of the Future or the Future of Bridges?

Infrastructures are a key factor for economy. Among them, transportation infrastructures are vital for human life and economy. And within the transportation networks, bridges are key elements for connecting people and delivering goods. For this reason, bridges have been built since many centuries ago and, in some way, the advances (and sometimes geographical expansions !!) of ancient cultures all over the world have been related to their ability of constructing permanent bridges. The most representative of this could be the Roman Empire. After many centuries of bridge construction, nowadays we face a long history of experiences that allow us to look to the evolution of bridge engineering along years and, based on that, to try to extrapolate what is the most feasible to come in the next future. The evolution in bridge engineering has been strongly linked to the key advances in the following areas: materials, construction processes and modelling. Construction techniques and bridge typologies at the beginning were governed by the mechanical properties and performance of available materials at that time. In fact, when the available materials were stone and masonry ( materials that work well in compression but not in tension), the characteristic bridge type was the arch and the construction process the scaffolding of the complete structure because the arch action needs the complete structure to develop. For centuries the arch was the only available bridge type regarding permanent bridges. Of course, suspension and beam configurations were also available but normally with temporary use due to the durability limitations of materials working in tension (vegetal fibres) and bending (timber). Only the appearance in the 19 th

Study on a novel dual-mode interconnected suspension

To achieve an optimal solution for the conflicting vehicle performance requirements, such as the handling stability and ride comfort, a novel dual-mode interconnected suspension (DIS) with a switching configuration depending on the vehicle working conditions is proposed in this paper. The DIS system has two modes: default mode and anti-pitch mode, and the DIS system configuration and working principle are presented, and a mathematical model is derived based on the hydraulic circuit flow-pressure relationships. Then, the switching threshold is optimised, and the behaviours of four vehicles with different suspension configurations are studied under different manoeuvres. The simulation results demonstrate the proposed DIS suspension's benefits in reducing vehicle roll/pitch motion and improving vehicle ride comfort, and it has the potential to be widely used in the future.

An investigation into the effect of suspension configurations on the performance of tracked vehicles traversing bump terrains

This is a theoretical investigation into the effect of various suspension configurations on a tracked vehicle performance over bump terrains. The model developed is validated using published experimental data of the modal characteristics of the vehicle. The desired performance is based on ride comfort via the mixed objective function (MOF), which combines the crest factor of bounce acceleration, bounce displacement, angular acceleration, and pitch angle. The optimisation process involves evaluating the MOF for different numbers and locations of dampers and under different rigid bump road conditions and speeds. The system responses of the selected suspension configurations in the time and frequency domains are compared against the undamped suspension. The results show that the suspension configurations have a significant effect on the vehicle mobility over bump road profiles. For a five-road–wheel half model of a tracked vehicle, the maximum number of dampers to use for ride comfort over these road bumps is three with the dampers located at wheel positions 1, 2 and 5. This confirms the current practice for many tracked vehicles with 10 road wheels. However, it is further shown that the suspension fitted with two dampers at the extreme road wheels offer the best performance over various rigid bump terrains.

Passive vehicle suspensions employing inerters with multiple performance requirements

This paper investigates passive vehicle suspensions with inerters by considering multiple performance requirements including ride comfort, suspension deflection and tyre grip, where suspension deflection performance is novelly considered which is formulated as a part of objective functions and a constraint separately. Six suspension configurations are analyzed and the analytical solutions for each performance measure are derived. The conditions for each configuration to be strictly better than the simpler ones are obtained by presenting the analytical solutions of each configuration based on those of the simpler ones. Then, two stages of comparisons are given to show the performance limitations of suspension deflection for passive suspensions with inerters. In the first stage, it is shown that although the configurations with inerters can improve the mixed performance of ride comfort and tyre grip, the suspension deflection performance is significantly decreased simultaneously. In the second stage, it is shown that for passive suspensions with inerters, suspension deflection is the more basic limitation for both ride comfort and tyre grip performance by doing comparisons among mixed ride comfort and suspension deflection optimization, mixed ride comfort and tyre grip optimization, and mixed suspension deflection and tyre grip optimization. Finally, the problem of mixed ride comfort and tyre grip performance optimization with equal suspension deflection is investigated. The limitations of suspension deflection for each configuration are further highlighted.

Analysis of RF Signal Interference Invasion Into Hard Disk Drive System and Coupled to Read Front-End System

Disk drives' high data rate frequencies now occupy the same radio-frequency (RF) signal frequency bands of wireless communication networks. RF signals invade into the disk enclosure (DE) through the hard disk drive's slots, which are created by the gap between the top cover and the base between screws. Poor immunity DE designs allow wireless RF signals to interfere with the low-amplitude read signal of the customer's data. It is important to find the invasion path of the RF signal interference, and to apply the countermeasure to improve RF immunity. To determine the best configurations for RF immunity from a slot to the read path, this paper compares the RF immunity among four kinds of signal-trace suspension configurations by two kinds of extrinsic RF coupling measurement methods. Analysis shows that proper ground routing of some signal return traces can significantly improve RF immunity, and electrostatic discharge protection.

Suspension culture of hepatocyte‐derived reporter cells in presence of albumin to form stable three‐dimensional spheroids

Several studies in the past have formed 3-dimensional (3D) spheroids of primary hepatocytes in suspension culture. Unfortunately, primary hepatocytes in a suspension environment tend to lose their differentiated function over time, generally due to damage from fluid shear stress and eventual spheroid settling. We have therefore created a novel suspension culture system, by seeding H35 rat hepatoma cells, a hepatocyte-derived cell line, in a 24-well tissue culture polystyrene (TCPS) plate placed atop an orbital shaker to create 3D spheroids. To provide stability to the formed spheroids, we used a long-chain polymer, bovine serum albumin (BSA), dissolved in the cell culture medium and/or coated on TCPS surfaces placed in suspension configurations. Our results demonstrate that BSA coating of culture surfaces resulted in uniform and well-defined spheroids with little spheroid settling or "flattening" of cell colonies in either static or suspension configurations. In BSA-coated suspension systems, spheroid size scaled with the amount of BSA dissolved in culture medium. In static uncoated cultures, the normalized rat albumin production levels were enhanced by addition of BSA within culture medium. Thus, both addition of BSA to culture medium and application of BSA as a surface coating appear to be meaningful avenues for tailoring spheroid morphology and function. This 24-well plate suspension culture system may be a valuable tool for high throughput investigations of liver cell behavior in a stable, uniform, 3D spheroid state.

Modelling generalisation and power dissipation of flexible-wheel suspension concept for planetary surface vehicles

Flexible-wheel (FW) suspension concept has been regarded to be one of the novel technologies for future planetary surface vehicles (PSVs). This study develops generalised models for fundamental stiffness and damping properties and power consumption characteristics of the FW suspension with and without considering wheel-hub dimensions. Compliance rolling resistance (CRR) coefficient is also defined and derived for the FW suspension. Based on the generalised models and two dimensionless measures, suspension properties are analysed for two FW suspension configurations. The sensitivity analysis is performed to investigate the effects of the design parameters and operating conditions on the CRR and power consumption characteristic of the FW suspension. The modelling generalisation permits analyses of fundamental properties and power consumption characteristics of different FW suspension designs in a uniform and very convenient manner, which would serve as a theoretical foundation for the design of FW suspensions for future PSVs.

Active suspension for a two-axle railway vehicle

The aim of this paper is to investigate how the ride quality of a two-axle railway vehicle with single-stage suspension might be improved by the use of active control, compensating for the lack of the double suspension stage, and thereby taking full advantage of vehicle lightweight construction. The basic requirement is to improve the ride quality on random track unevenness while keeping suspension deflection within acceptable levels when the vehicle negotiates deterministic track features such as a gradient. Two active suspension configurations are considered – skyhook damping and linear quadratic Gaussian (LQG) optimal control. Finally, actuator dynamics are included in the analysis, to assess the impact on the overall success of an active suspension implementation. The paper shows that both skyhook and LQG control strategies offer significant improvements in ride quality and also that careful design of the actuators and their force control loops is essential.

Deduction of the Rocker-type Track Suspension Configurations and Their Applications to Coal Mine Rescue Robots

To obtain robot's locomotion mechanisms which have good passive adaptability to rugged unstructured terrain and strong obstacle-surmounting capabilities to regular obstacles such as steps and ditches,the track is introduced into the rocker-type robot mobile system.Various configurations of the rocker-type track suspensions are obtained through adding arm-tracks and fixing joint angles,and their characteristics are analyzed.According to the unstructured terrain environments and the explosive gas atmosphere environment of underground coal mine,a rocker-type tracked mobile system using a symmetrical W-shaped track suspension is presented,and the mobile platform prototype is developed.Obstacles-surmounting capabilities of this mobile system,such as anti-overturning,channel-crossing,stair-climbing,down-stair,are analyzed.The capability analysis and test results indicate that the platform is of good adaptability to complex unstructured terrains and of strong obstacles-surmounting capabilities,and it can climb up a 100 mm-high step,climb down a 450 mm-high step,and cross a 260 mm-wide ditch.

Roll- and pitch-plane coupled hydro-pneumatic suspension

Passive fluidically coupled suspensions have been considered to offer a promising alternative solution to the challenging design of a vehicle suspension system. A theoretical foundation, however, has not been established for fluidically coupled suspension to facilitate its broad applications to various vehicles. The first part of this study investigates the fundamental issues related to feasibility and properties of the passive, full-vehicle interconnected, hydro-pneumatic suspension configurations using both analytical and simulation techniques. Layouts of various interconnected suspension configurations are illustrated based on two novel hydro-pneumatic suspension strut designs, both of which provide a compact design with a considerably large effective working area. A simplified measure, vehicle property index, is proposed to permit a preliminary evaluation of different interconnected suspension configurations using qualitative scaling of the bounce-, roll-, pitch- and warp-mode stiffness properties. Analytical formulations for the properties of unconnected and three selected X-coupled suspension configurations are derived, and simulation results are obtained to illustrate their relative stiffness and damping properties in the bounce, roll, pitch and warp modes. The superior design flexibility feature of the interconnected hydro-pneumatic suspension is also discussed through sensitivity analysis of a design parameter, namely the annular piston area of the strut. The results demonstrate that a full-vehicle interconnected hydro-pneumatic suspension could provide enhanced roll- and pitch-mode stiffness and damping, while retaining the soft bounce- and warp-mode properties. Such an interconnected suspension thus offers considerable potential in realising enhanced decoupling among the different suspension modes.

A model-less technique for the fault detection of rail vehicle suspensions

This paper presents a novel method for the fault detection and condition monitoring of rail vehicle suspensions. The proposed technique takes advantage of the vehicle (suspension) configurations that are often symmetrical, and explores the additional dynamic interactions between different motions of a bogie or body caused by the failure of suspension components. The basic principle of the proposed detection method is presented and the interactions due to suspension fault conditions are analysed using a conventional two-axle bogie. Side-view models of a bogie vehicle are used in the study to demonstrate the effectiveness of the novel method in detecting damper faults in the suspensions. Both linear and bi-linear dampers are studied.

A method for predicting dynamic behaviour characteristics of a vehicle using the screw theory — part 1

This paper presents the development of a prediction method for vehicle dynamic behaviour characteristics using screw axis theory. A vehicle model is developed for quasi-static analysis which is applied to vehicles of three different suspension configurations under cornering conditions in which a specific lateral force acts. A finite screw axis is determined using quasi-static analysis based on a rigid body displacement of the vehicle model with respect to the ground. The fixed screw axis surface formed by the migration of the finite screw axis is also determined. The shape of the fixed screw surface shows that the fundamental characteristics of vehicle roll behaviour is determined not by suspension tuning element but by suspension geometry. The gradients of screw parameters with respect to lateral force when the vehicle model behaves in an initial cornering state are proposed as prediction parameters of vehicle dynamic motion. The dynamic analysis result shows that vehicle dynamic motion characteristics can be successfully predicted by the proposed parameters.

Dynamic Road Load Simulation of Transportable Cranes

This paper develops a general tool for understanding the dynamic road loads generated by mobile cranes that use a boom support dolly. The focal point is the dynamic road loads generated by the vehicle, which is a primary cause of pavement damage. A pitch plane model of the crane is developed and a finite element model is used to characterize the flexible motion of the boom. The simulation can characterize both the traditional and modern styles of mobile cranes. The traditional style uses a walking beam suspension on the carrier and a leaf spring suspension on the dolly. The modern cranes implement a hydropneumatic carrier suspension and an air ride suspension on the dolly. Additionally, other suspension configurations are implemented. The simulation results show that modern cranes generate significantly lower dynamic loads than do traditional cranes. This indicates that there is a need to regulate axle load limits in a manner that compensates for different suspension systems.

Numerical and Experimental Simulation of Mountain Bike Suspension Systems Subject to Regular Impact Excitation

The aim of the work reported here was to investigate the potential benefits of rear suspension systems for mountain bikes and to develop numerical models that could be used in future to help with the design of improved suspension configurations. As the basis for a study of the effect of rear suspensions, two bicycles were chosen: one with full suspension and one with only front suspension (hard tail). Apart from the rear suspension, all other aspects of the bicycles were closely matched. In order to control the number of variables, a special rolling road test rig was used. Eight subjects were asked to ride each bicycle on the rig in random order. Measurements were taken of pedal torque and speed, rear wheel speed, forward thrust at front axle and vertical acceleration at the saddle and handlebars. Physiological measurements were also taken, but these are reported elsewhere. A DADS model of the rolling road rig, bicycle and rider was created and numerical simulations were performed. The results of the numerical simulations compared well with the experimental results. Unmeasured parameters predicted by the DADS model could therefore be used with reasonable confidence to aid the understanding of the suspension performance. Physiological results, mechanical measurements and simulation results all indicate that the full suspension bicycle shows a significant improvement in terms of comfort and energy expenditure when riding over regular bumps. The good correlation between measurement and simulation provides a tool that can be used in future for optimization of bicycle suspension design.

Fundamental Issues in Suspension Design for Heavy Road Vehicles

Heavy road vehicles play an important role in the economy of many countries by providing an efficient means of transporting freight. Such vehicles can also have a significant impact on safety, the infrastructure and the environment. The design of the suspension affects the performance of the vehicle in terms of ride, infrastructure damage, suspension working space, energy consumption, rollover stability, yaw stability, braking and traction. The published literature on suspension design for heavy road vehicles is reviewed. It is found that extensive knowledge exists, but that there are areas where improved understanding is needed. Areas identified as fundamental issues requiring attention include ride discomfort criteria, secondary suspensions, and controllable suspensions. Two issues in particular are examined in detail: suspension tuning and suspension configuration. In the tuning of suspension parameter values for vibration performance, numerical optimisation techniques have been used extensively, but generic tuning strategies have not been widely developed. Modal analysis is proposed as a technique for gaining the insight into vehicle vibration behaviour necessary to enable tuning strategies to be devised. As an example, the technique is applied to the pitch-plane vibration of a tractor-semitrailer. In analyses of new suspension configurations or concepts, comparison with alternative concepts is not always made. Lack of such comparisons makes the selection of an optimum concept difficult. Analysis of alternative concepts using simple mathematical models, and comparison of their performance using common criteria, is advocated for enabling informed selection of an optimum. An example involving two alternative roll control systems is used to demonstrate the issue.

Type Synthesis of Vehicle Planar Suspension Mechanism Using Graph Theory

This paper presents a graph theory-based approach to optimum type synthesis of vehicle suspension mechanisms using an expert system. Kinematic chain isomorphism is identified, using an extended degree method to facilitate the enumeration of kinematic structures. Rules representing design criteria and the flow value theory based on energy loss calculation are incorporated in the rule base to evaluate and select mechanisms among those that are enumerated in the database. Statistical variance calculation serves to complement the flow value theory. A new method called the extended flow value method is devised for isomorphism checking of labeled graphs. In the spirit of increasing emphasis on the riding quality of vehicles, several novel suspension configurations are created to ensure maintenance ease and vibration damping efficiency.

Design Loadings and Structural Considerations for Tracked Air Cushion Research Vehicle

Simple analyses of vehicle responses to operating conditions are used as the basis for determining the types of loading significant for structural design of the Tracked Air Cushion Research Vehicle (TACRV). A brief development is given for the methods used to determine the magnitude of cushion applied loads along with the internal reactions and load paths associated with the several suspension configurations. Although the choice of materials and conservative design safety factors tend to preclude fatigue problems for the test vehicle, a brief analysis is given to indicate some potential fatiguecritical areas in tracked air cushion vehicle (TACV) prototypes designed to higher stress levels.

Truck suspension systems optimization

This paper describes a test program and computer simulation aimed at optimizing the riding qualities of a military tractor-semitrailer combination. Instrumented testing was conducted with a variety of suspension configurations. Test results were correlated with computer simulation.