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Siemens PLM Software
LMS Engineering services
Road load data prediction with TWR
Saving time and resources by combining test and simulation
Benefits
• Save time and resources
by avoiding complex
and expensive modeling
of a driver, tires and a
digitized road
Summary
LMS™ Engineering services combine test
and simulation to calculate model drive (or
input) loads, enabling efficient extraction
of relevant vehicle and component loads
for durability studies.
• Accurately predict loads on
elements such as the strut
mounts and body
Defining correct road loads and understanding how they affect individual vehicle
components is crucial for successful durability simulation. However, due to acquisition complexity, measurement data is
usually either only partially available, or
not available at all. Multibody simulation is
a reliable technology for conducting road
load predictions. But modeling a driver,
tires and a digitized road is complicated.
Time waveform replication (TWR) embodies
a pragmatic way to include test-track
measurements in simulation. The process
replicates a laboratory road-load test using
an unconstrained multibody model and
experimental data, and yields back-calculated equivalent drive signals through an
iterative control technique.
• Employ unconstrained
vehicle simulation, leading
to more accurate body input
loads compared to a fixedvehicle approach
• Integrate the complete road
load prediction process in a
single environment
• Couple dynamic full-vehicle
simulation and time
waveform replication
• Replicate a laboratory roadload test using simulation
Test data acquisition.
www.siemens.com/plm/lms
LMS
LMS Engineering services:
Road load data prediction with TWR
The process starts with TWR being used to
measure performance on the track, and
process gigabytes of raw mobile testing
data to subtract the durability-related
content. This data will be applied as a
boundary condition to an unconstrained
multibody model, including flexible and
active suspension components and their
controls. Any type and number of
measured data can represent the starting
point. Using an iterative control technique,
equivalent drive signals in the wheel
centers can be calculated. This avoids the
need for modeling complex items, such as
a driver, tires and a digitized test track.
Afterwards, a forward multibody simulation, which corresponds to a durability
test rig, is used to produce results for
component and interface loads for further
durability simulation. The entire process
is completely integrated in a single
environment.
A typical TWR project is comprised of the
following phases:
Test-track measurements
LMS Engineering experts have vast
experience instrumenting vehicles for
track measurements and running test
campaigns. The acquired data is then
consolidated by operations, such as removing anomalies, filtering and deriving new
channels based on mathematical operations. Afterwards, LMS Engineering
employs dedicated data interpretation
methods to qualify and quantify the
durability potential, and convert it into
simulation input.
Multibody model creation
LMS Engineering experts build an unconstrained multibody model of the vehicle
using LMS Virtual.Lab Motion™ software.
Using LMS Tecware to show test data analysis.
Multibody simulation.
This tool has a powerful solver and can
be used to account for flexible bodies
and model active suspension systems
with their controls thanks to co-simulation
with LMS Imagine.Lab Amesim™ software.
The TWR-based approach does not require
modeling of complex items, such as a
driver, tires and a digitized road.
Calculating displacement drives
using TWR
LMS Engineering experts use the LMS
Virtual.Lab Motion multibody model to
calculate the displacement drives in the
wheel centers that replicate the earlier
measured data using an iterative
control method.
Extracting the interface forces
The displacement drive signals are now
used to calculate the effect of road loads
on the individual components and interface
points. For example, the isolated loads on
the body or subframe can be transferred
to the durability department to conduct
detailed fatigue life prediction analysis.
Contact
Siemens PLM Software
Americas
+1 248 952 5664
Europe
+32 16 384 200
Asia-Pacific +852 2230 3308
www.siemens.com/plm
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Management Software Inc. Siemens
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