Vehicle Crashworthiness and Occupant Protection - Chapter 3

Vehicle Crashworthiness and Occupant Protection
This is of interest as it indicates that the model captured the overall stiffness of
the deforming vehicle structure.
Figure 3.6.4.5 shows the barrier unfiltered force-time pulse. The pulse shape with
its two peaks and the times at which they occurred is consistent with experimental
data.
The first peak force almost coincided with the results obtained from one test.
However, the second peak was only 60 percent of the test value. This may be due
to inexact modeling of the engine-to-dash panel interactions.
Subsequent to development of the integrated model, to illustrate its robustness it
was exercised to simulate an NCAP test. Figure 3.6.4.6 shows the model
deformations at 100 ms corresponding to impact with a full rigid barrier from an
initial speed of 35 mph.
Next, the model was exercised to simulate vehicle frontal impact with a rigid pole.
The initial impact speed was 30 mph. Figure 3.6.4.7 shows the initial model set-up
and the deformed configuration at 100 ms.
Finally, the model was tested to simulate vehicle impact with an offset rigid barrier.
The initial vehicle speed was 30 mph. The vehicle impact was on the left side with
50 percent barrier overlap. The initial model configuration and deformed
configuration at 100 ms is shown in Figure 3.6.4.8. A comparison of frontal vehicle
deformations in time is shown in Figure 3.6.4.9, which clearly demonstrate the
difference in frontal deformations corres-ponding to the previous four impact
scenarios.
3.7 Summary
Although the FE technology for structural mechanics was introduced in the early
sixties, it took about 25 years of additional development to apply it successfully
to crashworthiness simulation of automobile structures. The developments were
mainly in nonlinear problem formulation of shell elements, reduced spatial
integration, explicit time integration, plasticity, and contact-impact treatments.
The role of super computers and code vectorization was indeed indispensable for
the development of full-scale vehicle models.
The mid-eighties to the mid-nineties time span can be characterized as the
renaissance period of FE crashworthiness models. Generic and actual components
of vehicle structures as well as full-scale vehicle models were developed to simulate
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