Arc far Side Impact Collaborative Research Program – Task 5b: Test Procedures Crash Tests and Sled Tests for the Far-side Environment

1.3IIHS Crash Test Deformations vs. Model Results

The IIHS database of side crash tests was examined to determine crush profiles of vehicles tested. The data on the following 12 vehicles were available:

Honda Accord, Nissan Altima, Toyota Camry, Subaru Forrester, Mitsubishi Galant, Saturn L series, Chevy Malibu, Mazda 6, Volvo S40, Saab 9-3, Hyundai Sonata, Dodge Stratus.

A plot of the average deformation at the mid level of the door for the 12 vehicles is shown in Figure 8 as the plot in blue. The average delta-V of these tests was 23.6 kph. The average CDC extent of deformation was 2.2. The pink plot shows the FEM simulation for a IIHS barrier impact with a Ford Taurus at a delta-V of 25.8 kph.

The higher deformation in the FEM simulation is partially due to the elastic component of deformation that is present in the FEM results but not in the IIHS test results. After the test there is a spring-back of the door structure. There may also be differences due to the higher delta-V for the FEM test. Finally, the model may not account for some of the structural interactions including seat and floorboard interactions.

Figure 9 provides two adjustments to the FEM model. The red curve adjusts the FEM deflection for spring-back. Scaling the FEM curve by a factor of 0.7 brings the FEM model close to the IIHS average deformation pattern..

Figure 8. Side deformation – Average of 12 IIHS Tests with Delta-V of 23.6 kph and Predictions from FEM Model with a Delta-V of 25.6 kph


Figure 8. Side deformation – Average of 12 IIHS Tests with Delta-V of 23.6 kph and Predictions from FEM Model with a Delta-V of 25.6 kph; Adjustments to FEM model for Spring-back and Other

1.4Discussion

Figure 9 shows a comparison of the residual deformation typical of IIHS tests and the deformation predicted by the Taurus model. The predicted shape of the deformation matches the test data. However, the extent of deformation predicted by the model is higher. This result suggests the need for further validation of the model to predict the extent of damage. However, the model is assumed to be useful in predicting the shape of the damage.

The shape of the damage predicted by the model for the IIHS test was generally similar in shape and extent to the damage produced by a pickup impacting the occupant compartment. Both the NCAP test and the Y damage test produced less damage to the front door than the IIHS test or the pickup impacts with the occupant compartment. This observation indicates that the IIHS barrier is the most suitable for simulating vehicle impacts to the front door of the occupant compartment.

As reported in Chapter 2, the average CDC extent of damage for far-side occupants who sustain AIS 3+ injuries is 3.6. The average CDC extent of damage produced in the IIHS tests plotted in Figure 9 is 2.0. This difference suggests that the far-side test aped should be higher than the near-side test speed used by IIHS.

The maximum deformation for the pickup impact was within 230 cm of the centerline of the Taurus. This produced an extent of damage of approximately 3.6. The Y-damage impact produced a lower extent of damage than that produced by the central impacts.

1.5Conclusions

The Finite Element Models indicate that the IIHS barrier produced similar damage on a Taurus patterns to those produced by a full size pickup truck. The NHTSA barrier and the Y damage test produced less damage to the Taurus front door than the IIHS barrier.

The average CDC extent of damage produced in actual IIHS crash tests is considerably less that the average extent of damage to vehicles with far-side occupants injured at the AIS 3+ severity.

Further work is needed to validate the FEM model at the higher crash severities that cause serious injuries in far-side crashes.

1.6References

Guerra, R.C., "A Refined Methodology for Vehicle Finite Element Modeling Incorporating Robust Capabilities, Fine Uniform Mesh, and Comprehensive Interior" A Thesis for the School of Engineering and Applied Science of The George Washington University, August 13, 2004, 

Kildare, S., “Report on the Progress of Work on the Development of Finite Element Models of the FMVSS 214 and IIHS Side Impact Barriers”, GW Report, January 2005.

2Human Facet Model Validation and Dummy Evaluation

2.1Introduction

The objective of this task is to use either of the two MADYMO human models provided by TNO – finite-element and faceted – to create a model that accurately simulates occupant motion in far-side impacts. This model will then be used as the baseline for future modeling. An initial application included in this task will be the a comparison of the kinematics of dummy and human models in the far-side crash environment.

To date, anthropomorphic test devices (ATD’s) have not been designed with consideration for human motion in far-side impacts. Thus leaving the question whether ATD’s designed for frontal impacts or near-side crashes can adequately be used to model human motion in far-side. Previous tests with a BioSID dummy confirmed that the dummy does not suitably model the human motion, especially with consideration to the spine, since it is rather rigid. This was compared with a similar test with a human cadaver in far-side. (Fildes et al., ICROBI, 2002)

Previous MADYMO modeling by George Washington University National Crash Analysis Center showed that motion of a Hybrid III, BioSID, EuroSID 1, EuroSID2, or SID2s did not accurately reflect the motion of a human cadaver under the same impact configurations as a cadaver test of a far-side crash at Medical College of Wisconsin. (Alonso, 2004). These dummies mostly constructed with rigid spines did not exhibit the same excursion toward the far-side surface as the human cadaver did. Head contacts to the far-side surface are noted in real-world crash reconstructions under similar circumstances. Thus, we know that occupant displacement is farther than a current crash dummy predicts.

Figure 1 illustrates these MADYMO dummies compared with a cadaver test.

Figure 1: Dummy Models in Far-side with Cadaver Comparison - Hybrid III, BioSID, EuroSID 1, EuroSID2 and SID2s

From top left to top right, the dummies are Hybrid III, BioSID, and EuroSID 1. The bottom left and center are EuroSID 2 and SID2s, respectively. These dummy models were completed with a crash pulse from a 2000 Taurus side impact NCAP test at 62 kph. The cadaver video, at the bottom right, shows the head excursion of the dummy does not nearly match that of the cadaver in relation to the passenger seat. This cadaver test was performed at a slightly higher speed of 65 kph.

In addition to the ATD MADYMO models, TNO provides two human cadaver models. One based on finite elements and another more simple one with faceted surfaces. These two models are examined for suitability in far-side impacts.