Welcome to the Online Presentation of RaceSim - PowerPoint PPT Presentation

Title: Welcome to the Online Presentation of RaceSim


1
Welcome to the Online Presentation of RaceSim
by
Back to Homepage
To navigate the slides Please use the Arrow
Buttons in the Bottom Bar and Menus on the Left
or Bottom right Button for Full Screen
View and use Space Bar for Navigation (Esc to
Exit) Note This feature requires Internet
Explorer 4 or higher
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Masses Input
The chassis is a seven-degree of freedom model
(pitch, yaw, roll translations front and rear
plus chassis twist). The inputs are sprung and
unsprung masses and inertias. Go to extras-mass
calculate to calculate CGs and inertias from
lumped masses.
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Chassis
Input basic chassis dimensions and
characteristics. Note torsional free-play term.
Not necessarily desirable but often present. If
values such as chassis torsional damping and/or
free-play is unknown, input zero and the
calculation will continue without these
parameters. Input Steering characteristics. Frame
heights function is for calculation of dynamic
ride heights at 4 user defined points on the
chassis.
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Independent Kinematics
The suspension kinematic is described by a wheel
displacement versus orientation line/curve e.g.
camber versus bump travel etc. Non-linearity is
described by a quadratic equation. Go to
extras-parabola to assist with curve fitting and
equation determination. Input roll and pitch
center static position and linear or nonlinear
movement versus wheel displacement. Input camber
and toe compliance versus loadings. All inputs
are for each wheel independently.
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Live Axle
Select a solid axle for front or/and rear left
and right corner. Like the independent suspension
the solid axle kinematics describes a wheel
displacement versus orientation line/curve
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Springs
Select front-rear, left, right or middle
unit. Input spring, helper spring, bump stop
stiffness and stroke. Use parabola tool for
quadratic (nonlinear) curve fitting.
7
Dampers
Input five force versus speed data points for
bump and rebound for each suspension damper,
import directly from Roehrig dyno or contact
D.A.T.A.S. Ltd. regarding import of damper dyno
data into RaceSim. Shaft friction may be modeled
and there is a linear coefficient output for use
with critical damping calculations.
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Anti Roll Bar
Input front and rear (linear or non-linear) roll
stiffness and/or damping at the wheel.
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Tyre
The tire characteristic is basically described by
high and low vertical load, longitudinal and
lateral friction (force) and self-aligning
torque versus slip angle curves. Corner Stiffness
is used to define the initial gradient and a
maximum and a constant value to describe the
typical digressive characteristic. Toggle
between lateral, longitudinal or aligning torque
to view respective curves. Pacejka data may be
imported and the calculation will be driven by
the Pacejka curves.
Vertical damping, hysteresis angle (response),
ellipse factor (combined long./lat. force),
rolling resistance (friction) and camber
stiffness (thrust) help to detail characterize
the tyre. Growth with speed is essential for
aerodynamically (ht. sensitive) influenced
vehicles and for maximum RPM. The temperature
model is to assist the user to characterize the
tyres, and to enhance the manufacturers data.
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Engine
Select engine orientation, rotational direction
and drive split. The engine (drive train) is
defined by a DIN power verses RPM curve, with
modifiers for driveline efficiency, dyno
conditions verses current ambient, traction
control and response e.g. turbo lag. Imput off
throttle torque (engine braking) and select
advanced engine model if required.
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Advanced Engine model
Input dyno conditions. Input models for airbox
pressure correction, torque and injection
maps. Input model for the effect of the exhaust
gas on the vehicle external aerodynamics. Input
inertia for each gear. Back to Engine window.
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Gearbox
Select the type of gearbox CVT, optimum shift
revs (to peak torque at the wheel), static shift
revs (to shift rev limit) or individual shift
revs. Define number of gears, shift time (gear
change/engine cut duration) and driveline
efficiency per gear.
Input tire circumference from the tyre model.
Gear ratio variations may be selected from the
previously inputted drop down dialog boxes and
the speed/RPM graph overlaid or
redrawn. Numerical data may be viewed by pressing
the view data button and scrolling between data
sets.
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Brakes
Are defined by a maximum torque value front and
rear (therefore including the brake balance),
with a modifier for ABS and/or rear pressure
reducing valve (rear brake limiting). Select
balance finder for display of calculated dynamic
brake balance.
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Differential
Separate or combinations of front, rear and
center diffs may be modeled as a plate
(Salisbury) type or a viscous or a hybrid
plate/viscous combined. Select RPM ratio of the
output/input shaft for live axle if appropriate.
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Aerodynamic
The Aero properties of the vehicle are defined by
lift (downforce) and drag coefficients at a
reference ride height and speed. Variations in
coefficients with ride height and speed may be
inputted as a linear change or as a non-linear
(quadratic) for non-V squared variation. Again
use the extras-parabola tool to help determine
the quadratic equation. A variation of
coefficients when in the slipstream of a vehicle
ahead may also be modeled. Select more button
for variations of coefficients with roll, yaw and
wall proximity. The offset drag positions are
related to the vehicle CG for wind yaw
effects. Select with aeromap to load an aeromap
of coefficients verses front and rear ride
heights.
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Aeromap
As an alternative to manually inputting the
aerodynamic coefficients, an aero map chart of
lift/drag/balance verses front and rear ride
heights may be imported. Press plot to view a
rotational 3d plot of each function. Back to
aerodynamic
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Setup Calculation
Define time steps to optimize calculation time
verses resolution or use defaults shown in on
line help file. Reduced time step at brake or
throttle allows one to increase resolution in
these critical areas. Input lap sim reduced
lateral to model non optimum usage of lateral
tyre capacity. Input lap sim reduced
brake/throttle to model late braking and
therefore late accelerating driver or the
opposite . Steering torque limit may be set to
prevent torque feedback being in excess of the
drivers capability. Set overall (global) grip
and ambient conditions. Set check balance to
modify the effect of longitudinal weight transfer
on grip. Set reduce segment boxes to modify the
track map graphical display or use
defaults. Select logging file setup to edit
channel details.
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Lap Simulation
The track map may be created manually
segment-by-segment using the track editing boxes
or more usually by importing (ASCII) data of
speed and lateral acceleration from a data logged
lap. The imported track map may be manually
edited for example to modify the segment local
grip /or banking (track camber) to match real
and simulated minimum corner speeds /or
elevation profile to correctly match longitudinal
acceleration.
Automatic matching (to imported logged data) of
corner banking or local grip may be selected
from the drop down dialog box. Set wind
conditions, start speed and gear ratio per
segment. Set the level of simulation
(include/exclude heave, pitch, roll, steering)
from the drop down dialog box.
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Result Channels
Load file. Select channels to view approx. 65
channels from a possible c.90. Edit the channel
trace color, scaling, add/delete/ replace files,
delete lines (channel trace) for clarity.
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Result Graph
Match simulated lap to actual logged lap and
display simulated data. Manually move the curser
over the trace line and view data in curser
window. Press right mouse button to zoom in on
trace line - zoom off. Select dots on and zoom
to view data points. Select print if required.
Note this matched lap of Spa in less than ideal
grip conditions shows a 2 26.85 lap time and a
throttle lift at Eau Rouge. Now use RaceSim to
evaluate the effect of increasing aero downforce
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Modify Aerodynamics
After the lap matching is done, modify the model
and predict what the effects are. Here for
example with an increased wing setting, and
therefore increased lift (and drag) coefficients
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Compare Graph
Despite lower top speed and time loss on longest
straights, the overall effect of Increasing aero
from Low to Medium downforce improves lap time by
0.55 seconds to 2 26.30. Simulation predicts
more throttle opening and higher minimum corner
speed in Eau Rouge. A good result for
qualifying, although one would have to consider
the overtaking scenario for the race.
23
Transient Simulation
Select starting speed and end time (run
time). Select run by pilot and adjust throttle
and brake slide bars for conventional driveline
and brake torque effects or deselect run by
pilot for manual input of acceleration (drive)
and deceleration (brake) torque directly into the
drive shaft/brake caliper for pure kinematics
effects analysis. Select any steering input.
Define wind conditions. Define track surface
bumps and/or kerbs using the editing boxes.
Define track banking and lateral curvature.
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Dynamic ride height
Calculates the vertical displacement of the
vehicle due to aero effects (downforce), either
at a selected single speed or through the speed
range. This enables the user to predict the
dynamic ride heights (and therefore the potential
touch condition) at maximum speed, and thus
accurately set the static ride heights. Input
speed and press calculate.
25
Advanced 4 post
A stand alone tool, simulating a 4 post rig
vertical excitation, to calculate grip reduction
due to vertical stiffness configuration. The
calculation considers the stiffness and damping
configuration of the vehicle, and the output is
based on tire contact patch load variation at
user selected modes and conditions Select desired
mode and conditions and press calculate.
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Run assistant
Enables the user to run a batch of up to fifty
simulation runs, and therefore have a productive
lunch break.
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Result Animate
Load file, view real time (or slower) steering,
braking, throttle activity. View gear position,
speed, RPM, lateral and longitudinal
accelerations, force vector direction and
magnitude and wheel loads all dynamically.
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Mass Calculate
This tool calculates CGs, inertias and mass
distribtution for 7 lumped masses Back to slide
masses input
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Parabola
This tool helps to find the coefficients for a
quadratic polynomial to fit nonlinear real
curves. Back to Kinematic Back to Springs Back to
Aerodynamic
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