Ann Arbor, MI, United States
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Sharp R.S.,University of Surrey | Watanabe Y.,Mechanical Simulation Corporation
Vehicle System Dynamics | Year: 2013

Motorcycle racing teams occasionally experience speed-limiting vibrations of around 25 Hz frequency in mid-corner. The nature of the vibrations has not been closely defined yet and the mechanics are currently not properly understood. Conventional motorcycle-dynamics models are shown here to reveal the existence of a vibration mode that aligns with the experience being referred to, suggesting some explanations. Root loci for variations in speed or cornering vigour, demonstrating modal characteristics for small perturbations from trim states, are employed to indicate how the mode responds to changes in operation and design. Modal participation is examined for a lightly damped case. Influences on the natural frequency and damping of the mode are found and a way of stabilising the mode is suggested. © 2013 Taylor and Francis Group, LLC.


Gillespie T.,Mechanical Simulation Corporation | De A. Lima V.,Virtual CAE
SAE Technical Papers | Year: 2015

Heavy trucks with solid front axles commonly use steering systems that have left to right asymmetry. The asymmetry creates the potential to cause steering pulls during brake application which are by their nature undesirable since they require an input in the steering wheel by the driver to maintain the correct path of the vehicle. Brake forces acting in the tire contact patches create toe-out moments around the kingpin axes that are resisted by the steering linkages. However asymmetry of the linkage allows unbalanced toe-out steer angle deviations at the wheels resulting in a path deviation of the truck that is perceived as brake steering pull. The factors influencing steering pull include the compliance properties of the steering linkages, road wheel geometry, drag link geometry and spring windup properties. The mechanics of the brake force interactions with these steering and suspension properties are explained here. Simulation provides an excellent tool to examine and quantify these interactions. The truck simulation model, TruckSim®, is used to show the importance of linkage compliance as a primary variable and the interactions with other steering and suspension properties. It will be shown that jounce steer and/or brake windup steer can be used to compensate for the unbalanced effects arising from the linkage asymmetry. Copyright © 2015 SAE International.


Duprey B.,Mechanical Simulation Corporation | Sayers M.,Mechanical Simulation Corporation | Gillespie T.,Mechanical Simulation Corporation
SAE Technical Papers | Year: 2013

In 2008 the Australian National Transport Commission (NTC) published a reference document titled Performance Based Standards Scheme - The Standards And Vehicle Assessment Rules [1]. This document describes a series of testing requirements known as Performance Based Standards (PBS) to be used for certifying truck configurations acceptable for the Australia highway system. The PBS specification allows for both in-vehicle testing and numerical analysis using simulation tools such as TruckSim [2]. Several of the PBS tests require a Low-Speed 90° Turn, used to measure tracking behavior and tire friction utilization. This test presents an unusual simulation challenge because the driver is required to closely track a path with the outer sidewall of the outside front tire. A human driver must learn the response of the vehicle in order to steer it accurately through the test. This paper describes how the learning process was simulated in TruckSim by using the built-in scripting language to monitor the tracking of the point of interest (outer sidewall of a tire) for drifting from the target path. If the drifting exceeds a limit, the script commands the simulation to jump back in time and continue with modified control settings. The simulation option to jump back in time requires software considerations that have not been included in commercial vehicle dynamics software until recently. This paper describes how the new capability is applied to mimic an advanced driver for this standard PBS maneuver using TruckSim. Copyright © 2013 SAE International.


Watanabe Y.,Mechanical Simulation Corporation | Sayers M.W.,Mechanical Simulation Corporation
SAE Technical Papers | Year: 2011

This paper describes modeling methods used in the commercial BikeSim ® simulation package to represent alternative suspension design concepts. The modeling method used for automotive suspensions is applied to define generic suspensions for motorocycles. This method can represent multi-link suspension systems as well as traditional motorcycle suspensions with telescopic front forks and rear swing arms. Comparisons of two suspension types show a multi-link suspension can provide advantages over the traditional system for braking, acceleration (throttle), and cornering. Similar comparisons made with a chain-drive powertrain and a shaft-drive powertrain show less jacking with the chain-drive design. Although the math models include complex nonlinear motions, the computational efficiency supports fast operation; on a 2.8 GHz PC the simulation runs eight times faster than real time. Copyright © 2011 SAE International.


Browalski E.,ACEC LLC | Jogi S.,dSPACE Inc. | Waraniak J.M.,SEMA | Gillespie T.D.,Mechanical Simulation Corporation | And 2 more authors.
SAE International Journal of Passenger Cars - Electronic and Electrical Systems | Year: 2010

The enactment of FMVSS 126 requires specific safety performance in vehicles 4,536 Kg (10,000 pounds) or less using an Electronic Stability Control (ESC) system as standard equipment by 2011. Further, in 2012, the regulation requires vehicles that have undergone aftermarket modification to remain in compliance with the performance standard. This paper describes: a brief overview of the standard and its implications the collaborative approach used in the first successful approach in meeting that requirement by a lift kit manufacturer o a Hardware In the Loop (HIL) test alternative for establishing a reasonable expectation for a vehicle to demonstrate compliance after modification. Collaborative challenges overcome: o aftermarket manufacturers seeking information sharing with OEMs and Tier One suppliers: o respecting the intellectual property of OEMs and Tier One suppliers o maintaining the integrity between tool competitors and their customers in cross-collaborative efforts. © 2010 SAE International.


Sayers M.W.,Mechanical Simulation Corporation
SAE International Journal of Materials and Manufacturing | Year: 2011

The major actions that move a highway vehicle are the forces and moments generated between the tire and ground; hence, the validity of a simulated vehicle test depends on the quality of both the tire model and the characterization of the ground surface. Other actions come from aerodynamic forces and moments that are affected by the relation of the vehicle body to the ground surface. This paper describes how the ground can be characterized to cover features of interest for most vehicle simulation scenarios involving pavements or other rigid surfaces. The 3D surface is built from tabular data related to specified properties of a road surface such as horizontal geometry, design elevation changes related to curves and drainage (i.e., banking of turns, cross-slope, ditches, etc.), elevation changes due to hills and other major grades, and disturbances and unique features such as bumps and holes. Broadband random-type road roughness is also included. The road model is intended to work with data from many sources, including GPS measurements, design data, road roughness profile measurements, 3D laser-scanned terrain topology, and specific scenarios created by engineers. A road axis system is defined for describing vehicle motions relative to an inclined road surface for aerodynamics and applications where engineers are concerned with motions of the vehicle relative to the ground surface. The methods described in this paper are demonstrated using the commercial CarSim® vehicle dynamics simulation package. © 2011 SAE International.


Duprey B.,Mechanical Simulation Corporation | Sayers M.,Mechanical Simulation Corporation | Gillespie T.,Mechanical Simulation Corporation
SAE Technical Papers | Year: 2012

The increasing use and implementation of computer simulation in the vehicle engineering process has allowed for complex vehicles to be designed and tested in a virtual environment prior to a full-size vehicle being built. This approach is of particular importance in the commercial truck markets of Australia, New Zealand, and South Africa where large truck-trailer combinations, often referred to as "road trains", are becoming more common. Such trucks can carry more freight per vehicle; however their overall length and mass means additional safety standards must be in place to ensure a safely operating vehicle. To that end the National Transport Commission (NTC) Australia has been developing vehicle specifications called Performance Based Standards, or PBS. Performance Based Standards include specifications for longitudinal performance such as Startability, Gradeability, Acceleration Capability, and Tracking ability on a straight path. Directional performance tests are Low Speed Swept Path, Frontal Swing and Tail Swing, Steer Tire Friction Demand, Static Rollover Threshold, Rearward Amplification, High-Speed Offtracking, and Yaw Damping Coefficient. The PBS specification allows both in-vehicle testing and numerical analysis. This paper describes how the PBS procedures are handled in the commercially available TruckSim vehicle simulation tool. It also describes how a set of large vehicle models made with a five-axle towing unit and various numbers of trailers with four axles are used to represent a majority of the "road train" vehicles. Copyright © 2012 SAE International.


Trademark
Mechanical Simulation Corporation | Date: 2011-08-05

Computer software for simulating and analyzing the dynamic behavior of motor vehicles; Simulators for driving or control of vehicles; Software for processing images, graphics and text.


Trademark
Mechanical Simulation Corporation | Date: 2011-08-05

Computer software for simulating and analyzing the dynamic behavior of motor vehicles; Simulators for driving or control of vehicles; Software for processing images, graphics and text.

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