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Ford Crown Victoria Crash Simulation
The The Silicon Valley Office of ARA has developed a high fidelity model of a Ford Crown Victoria for performing crashworthiness simulations. This study was part of an overall program sponsored by the National Highway Traffic Safety Administration (NHTSA) to develop a set of crash models for various vehicles that represent the full range of vehicle types currently on the road. This set of vehicle models can be used to establish the crash safety of future light-weight vehicles developed under the Partnership for a New Generation of Vehicles (PNGV) program.
The overall program to develop and validate a high-fidelity crash simulation model for the Ford Crown Victoria was a combined experimental and modeling effort under the management of the Volpe National Transportation Systems Center (VNTSC). MGA Research Corporation performed component validation tests on the Crown Victoria and had previously performed vehicle frontal and side impact tests. Results of
the vehicle tests are shown on the Crown Victoria Crash Test Video page. Component tests for this program included thefront bumper rigid
pole impact test, thefront door rigid pole impact test, and the vehicle frame rigid
wall impact test.
The preliminary phase in the development of a crash simulation model was the vehicle tear-down and measurement of the structural geometries. An illustration of the Crown Victoria in this tear-down process is shown in Figure 1. Once the nonstructural components were removed from the vehicle, tape was applied to the components to discretize the structure prior to measurement. An illustration of the Crown Victoria with the exterior surfaces discretized is shown in Figure 2. The resulting
measured surfaces were then modified to an appropriate format for use in the
vehicle model mesh generation program TrueGrid.
External surfaces, as seen in TrueGrid, are shown in Figure 3. These digitized surfaces were then used to generate the vehicle
components in the finite element model. The corresponding FE model is shown
in Figure 4.
Full vehicle
crash test data was available for the Ford Crown
Victoria
from testing performed under the
New Car Assessment Program (NCAP). This testing included both frontal barrier
and side impact testing. The NCAP frontal impact test was simulated with the
full vehicle model using the LS-DYNA finite element code. This frontal impact condition was a 15.6 m/s (35 mph)
impact of the vehicle into a rigid wall. The calculated vehicle response in
the frontal impact simulation is shown in Figure 5. Many of the characteristics observed in the tests were reproduced in
the simulation. The overall collision response produces a forward pitching
motion of the vehicle with a noticeable downward motion forward of the
passenger compartment and a lifting of the rear of the vehicle. The hood was
folded upward in the middle and the deformations were limited in the vehicle
behind the firewall. This vehicle frontal crash behavior can be seen clearly
in Movie 1.
The
calculated and measured wall impact force histories, for the NCAP frontal
impact test, are compared in Figure 6(a). The magnitude and time of the peak forces agree quite well. The
maximum impact force occurs at a time of approximately 55 ms and corresponds
to the time the engine is directly loaded through the crushed forward vehicle
components against the wall. The late time impact force history drops off
more rapidly in the simulation than in the experiment. This discrepancy may
result from additional mass in the test, such as crash dummies and
instrumentation that were not included in the current simulation. The
calculated and measured engine longitudinal accelerations are compared in Figure 6(b). The magnitude of the calculated peak acceleration is approximately
30 percent higher than that in the test with a shorter pulse width. Additional
analysis is required to determine the source of these discrepancies. The
calculated response also has a larger magnitude cyclic response during the
first 20 ms, which could be an artifact of the engine mount modeling.
The NCAP side
impact test was simulated with the full vehicle model and a model created for
the Movable Deformable Barrier (MDB). (Note: this model of the MDB was not
independently validated.) The side impact test was a 14.9 m/s (33.25 mph)
impact of the MDB into the stationary vehicle side. The wheels of the MDB
were angled at 27 degrees relative to its axis to represent the relative
motion of the two vehicles. The calculated vehicle response in the side
impact simulation is shown in Movie 2 and Movie 3. Many of the characteristics observed in the tests were reproduced in
the simulation. The overall crush of both the MDB front and the vehicle side
compare reasonably well with the test. The gross motions of both the MDB and
struck vehicle were also reasonably well calculated.
Comparisons
of the calculated and measured MDB accelerations are shown in
Figure 7. The magnitude of the longitudinal acceleration is slightly over
predicted in the simulation. This may be a result of either the car or the
crushable MDB models being slightly too stiff.
References
- S.W.
Kirkpatrick, "Development and Validation of High Fidelity Vehicle
Crash Simulation Models," SAE Publications, Presented at the 2000
International Congress and Exposition, March, 2000, SAE Paper No. 00PC-248.
Abstract 
- S.W.
Kirkpatrick, J.W. Simons, and T.H. Antoun, 1998,
"Development and Validation of High Fidelity Vehicle Crash Simulation
Models," Int. J. Crashworthiness, International
Crashworthiness Conference
Abstract
LS-DYNA - General
Purpose Transient Dynamics Finite Element Program.
For inquiries or comments, please contact:
Dr. Steven Kirkpatrick
Principal Engineer
e-mail: skirkpatrick@ara.com
Dr. Robert T. Bocchieri
Principal Engineer
e-mail: rbocchieri@ara.com |
