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This dictionary of terms was prepared for use by those with a need to describe and understand the dynamics and handling of two-wheeled, single track vehicles. It is intended to span the gap between vehicle dynamics specialists and those with a more general interest. This report is pertinent to such areas as vehicle design and development, the description of two-wheeler properties, rider training and education, and the preparation of standards and regulations. This report was prepared by the SAE Motorcycle Committee, which solicits suggestions for improvements and additions to be considered in future revisions. Comments should be directed to SAE Headquarters.

A simplified mathematical model of tandem suspension is presented to study the different parameters of tandem suspension. The equations of motion are compiled considering the system to be 3 degrees of freedom system, taking into accounts both oscillation and deflection of the leaf spring. The response characteristics for vibration isolation for the company test track road profiles at different speeds of the vehicle are calculated. The sensitivity of acceleration to variations in un-sprung masses and axle spacing is illustrated. Further, the usefulness of the model for studying the effect of shock absorber positioning on ride of tandem bogie suspension system is demonstrated.

Today, active dynamic control systems for commercial vehicles, offering improved safety, are frequently discussed. Yaw stabilising systems are based on theories from passenger car implementation, yet roll stabilisation - probably introduced in the near future - requires increased knowledge of rollover mechanics. Static analysis, providing steady state rollover threshold (SSRT), is the most common approach. Nevertheless in a rolling vehicle, kinetic energy is always present, deteriorating roll stability, invalidating the analysis. A simple method determining the dynamic rollover threshold (DRT) is therefore introduces in this paper. DRT is the worst case measure of roll instability: the conditions are necessary but not sufficient for rollover.

Electrorheological and magnetorheological fluids have found commercial application in a wide range of damping, force transmission and fluid flow arrangements, but are complex fluids, needing accurate rheological models for application design. In order to further the understanding of the behavior of these fluids under stress, a new lumped parameter (eight-element) model of shear-mode electrorheological fluid dampers has been developed. In this paper, the new model is presented and experimental data on damper force response is compared with model predictions over a range of sinusoidal input displacement amplitudes, input excitation frequencies and electric fields.

Ride quality of medium truck became a very important factor in the suspension design, due to the demand of more comfortable ride of passengers. This study describes how to determine and evaluate design parameters related to the chassis suspension system with time and frequency analysis. The spring stiffness and damping force of the chassis suspension system were obtained by observing the vertical acceleration PSD. The simulation was carried out on various road profiles, which was suggested by ISO. The pitching motion of the medium size truck was observed to improve the ride quality. A computer simulated truck model was constructed using DADS, a commercial dynamic analysis software, in order to simulate the truck motions. From the result of the sensitivity analysis of suspension parameters, it was concluded that the spring and the shock absorbers affect the pitching of the vehicle. In order to validate the computer simulated truck model, a physical prototype was constructed and tested.

Active and semi-active suspensions have been evaluated for application on tractor/semi-trailer trucks using a pitch plane simulation model called “VESYM”. VESYM is a fully nonlinear time domain simulation model. This paper reviews the effect of alternative heavy truck suspensions on pavement damage by using the flexible pavement simulation program “VESYS”, It is shown that by estimating axle tire force and using this signal to modulate a semi-active shock absorber that significant reduction in pavement degradation can be achieved.

In this paper we consider a new design of adaptive suspension systems of vehicles with better technical characteristics and functional abilities in comparison with existing designs. We have developed the following main suspension components of vehicles: a lockable adaptive shock absorber with a wide range of control performance, implementing "lockout" mode by means of blocking adaptive shock absorber, and an elastic element with progressive non-linear characteristic and automatic optimization of localization of work areas. Advantages of our developments in the vehicle suspensions are the following: 1) when the vehicle is in a wide range of speeds in a so-called "comfort zone", we have managed, by applying the non-linear elastic element, to reduce significantly the stiffness of the elastic suspension elements in compare with the regular structures - at least in two times. This means that comfort, smooth motion, high performance the vehicle when driving over bumps are improved in times.

We have developed a fundamentally new design of adaptive suspension systems of vehicles. Their technical characteristics and functional abilities are far better than the existing designs of suspensions. We have developed the following main suspension components of vehicles: a lockable adaptive shock absorber with an ultra-wide range of control performance, implementing “lockout” mode by means of blocking adaptive shock absorber, and an elastic element with progressive non-linear characteristic and automatic optimization of localization of work areas. Our patents confirm the novelty and efficiency of our major design decisions. Advantages of our developments in the vehicle suspensions are the following.

Steering pull during high speed braking of heavy commercial vehicles possesses a potential danger to the occupants. Even with negligible wheel-to-wheel brake torque variation, steering pull during the high speed braking has been observed. If the steering pull (i.e. steering rotation) is forcibly held at zero degree during high speed braking, the phenomena called axle twist, wheel turn and shock absorber deflection arise. In this work the data have been collected on the mentioned measures with an intention to develop a mathematical model which uses real time data, coming from feedback mechanism to predict the values of the measures in coming moments in order to aid steering system to ‘auto-correct’. Driven by the intention, ‘Time Series Analysis’, a well-known statistical methodology, has been explored to see how suitable it is in building the kind of model.

With the use of digital audio tape recorders and piezo accelerometers, a practical field-ready method of determining occupant loading has been developed for heavy truck and equipment ride evaluation. The primary objective in determining ride quality is to verify the accelerations transferred to the occupant through the seat. These accelerations can then be compared to occupant threshold limits to assist the engineer in determining ride quality. The acquisition of acceleration data can be done incrementally for each component of the vehicle, from the ground up to the seat cushion. This allows for an in-depth analysis of suspension and frame components which can then be used to fine tune the design. A secondary use of this method is to evaluate the interaction of contributing components to overall ride quality. Specifically, tires, shock absorbers, air bellows, spring rates, fifth wheel position and front axle position can be evaluated with this field ready method.

In the present scenario, delivering the right product at the right time is very crucial in automotive sector to grab the competitive advantage. In the development stage, validation process devours most of the product development time. This paper focuses on reducing the validation time for damper (shock absorber) variants which is a vital component in commercial vehicle suspension system. New test facility is designed for both performance test and endurance testing of six samples simultaneously. In addition, it provides force trend monitoring during the validation which increases the efficiency of test with an enhanced control system. This new facility is also designed to provide side loading capability for individual dampers in addition to the conventional axial loading. The key parameter during validation is control of damper seal temperature within the range of 70-90°C. A cooling circuit is designed to provide an efficient temperature control by re-circulating cold water.

Towed vibratory rollers are still commonly used for many soil compaction projects. Pneumatic tire vibration dampers are used for isolating vibration excited by drum frequency generation devices. Static stiffness of these air vibration dampers is different from standard tires. The configuration of the tire shell is an important influence upon damper stiffness. The vibration transmissibility can be changed by adjusting tire pressure to obtain the isolation effect desired within a small range.

The handling and ride comfort characteristics of a medium bus during a single lane change manoeuvre and bump pass are investigated in terms of the change of the center of gravity, stiffnesses of springs, and damping coefficients through computer simulation using DADS. Dynamic full model of the vehicle is established using tires, dampers, leaf springs, sprung mass, and unsprung masses. A driver is assumed to steer the vehicle along a prescribed path which was obtained from field tests. He was modeled as a PID controller in the simulation. In order to confirm the validity of the model, simulation results are compared with those obtained from field test. The handling and ride comfort characteristics of the vehicle are compared with root mean square values.

The slosh forces arising due to liquid motion in partially filled containers affect the roll dynamic stability of tank vehicles. In this paper, a simplified dynamic truck roll model has been developed considering both suspension flexibility and nonlinear dynamics of the liquid cargo motion. A small-scale experimental model for a cylindrical truck tank, excited in the lateral direction, is designed and constructed to measure the viscous damping and damped natural frequency of the liquid cargo. Since the viscous damping of the liquids is limited by its natural characteristics, partitions containing rectangular slots and holes of different sizes are used to generate additional damping. It is fitted against the lateral motion of the liquid slosh, i.e. parallel to and passing through the longitudinal axis of the vehicle. These types of partitions increase the motion damping of the liquid cargo and make the liquid behave like a dynamic absorber.

This study comprehensively describes the application of linear electromagnetic actuators in automotive suspension systems, focusing on the electromagnetic force necessary in suspension systems operating in passive, semi-active, and active modes and their capability for energy regeneration. The use of electromagnetic actuators as an alternative to traditional shock absorbers makes easy the energy harvesting that is typically lost during vertical vehicle displacement. An initial sizing technique for dimensioning electromagnetic actuators is applied to estimate the requirements for heavy vehicles. Experimental tests are conducted to validate the proposed method and assess the performance of the electromagnetic actuator in the suspension system for passive, semi-active, and active operations.

NVH is gaining importance in the quality perception of off-highway machine performance and operator comfort. Booming noise, a low frequency NVH phenomenon, can be a significant sound issue in an off-highway machine. In order to increase operator comfort by decreasing the noise levels and noise annoyance, a tuned mass damper (TMD) was added to the resonating panel to suppress the booming. Operational deflection shapes (ODS) and experimental modal analysis (EMA) were performed to identify the resonating panels, a damper was tuned in the lab and on the machine to the specific frequency, machine operational tests were carried out to verify the effectiveness of the damper to deal with booming noise.

This paper presents analytical expressions as well as simulations with a 3D – truck model to study roll and bounce damping for heavy vehicles. The objective is to illustrate the limits in performance resulting from the choice of dampers and mounting positions. Analytical expressions for a 2D - suspension model show that geometric key parameters controlling roll and bounce damping are damper vertical aligning and perpendicular distance between damper and suspension roll center respectively. In comparison to conventional damper positioning, roll damping for an alternative design may be increased with 75% for the unsprung mass without deteriorating desired bounce motion damping. Simulations using a 3D - truck model and selected load cases are furthermore used to investigate desired regions of roll and bounce damping. Results show that higher damping generally reduces corresponding motion. The amount of bounce damping is however limited by transient obstacles.

This study is made on a simplified pitch model of an armored fighting vehicle. Jerks and angular acceleration inside the vehicle compartment Affects accurate firing attack and reduced fatigue to the occupants in Vehicle. The Stability Augmentation Technique can enhance the stability and ride comfort of the vehicle platform from road and firing disturbance. The force requirement for stabilizing the platform is calculated from the displacement of vehicle body in terms of pitch angle and Heave displacement with respect to the equilibrium position, the equivalent force at suspension mounting points required to stabilize the platform is calculated using a force transformation technique. The required force is given by an active Damper for stabilization, within the limit of damper capacity.

Currently, a group of scientists consisting of six doctors of technical sciences, professors of South Ural State University (Chelyabinsk, Russia) has completed a cycle of scientific research for creation of adaptive suspensions of vehicles. We have developed design solutions of the suspensions. These solutions allow us to adjust the performance of the suspensions directly during movement of a vehicle, depending on road conditions - either in automatic mode or in manual mode. We have developed, researched, designed, manufactured, and tested experimentally the following main components of the adaptive suspensions of vehicles: 1) blocked adaptive dampers and 2) elastic elements with nonlinear characteristic and with improved performance.

The engineering objective was to design and develop a 40,000-lb. capacity tandem axle truck suspension mounted on air springs. It was to be developed from the existing Chalmers Series 800 rubber spring tandem suspension and was to provide a softer ride under all load conditions (Fig. 1). At the same time, the suspension was to be self-damping under any load condition without having to resort to shock absorbers.