EVALUATION OF CRASH TESTS OF THE INSTITUTE OF FORENSIC ENGINEERING, UNIVERSITY OF ZILINA, AIMED AT EES EVALUATION OF CRASH TESTS OF THE INSTITUTE OF FORENSIC ENGINEERING, UNIVERSITY OF ZILINA, AIMED AT EES

evaluation the vehicle on evaluation of the vehicle deformation work the comparison of vehicles tests speed), deceleration, deformation depth, stiffness.


Preface
The Institute of Forensic Engineering, University of Zilina, made in the course of 2012 a series of 5 vehicles crash tests focused on the evaluation of the vehicle deformation work, or of the EES of a vehicle, upon its impact with a fixed, non-deformable barrier with a full overlap.

Crash vehicles
For crash tests we used 5 vehicles with the age structure shown in Table 1. By yellow colour is highlighted a period when a given type of vehicle was produced, and by a red dot is marked the production year of the vehicle used in the crash test.
Photo documentation of individual vehicles before relevant crash test, including Euro NCAP evaluation of a given vehicle, is shown in Fig. 1.

Crash barrier
In the crash tests the vehicles were accelerated to the impact velocity by the Mercedes trailer and a pulley system, and they crashed into a solid concrete barrier of weight 10,000 kg (see Fig. 2).
But the given weight of the barrier was not sufficient to ensure a condition that no significant displacement of the barrier occurs, and therefore, the barrier was fixed using a blade of a recovery tank of weight 35,000 kg (see Fig. 3).

The results of crash tests
The following photos show (Figs. 4, 5, 6, 7 and 8) the damage to the vehicles after given crash tests, while in the description of the photo is always included the EES value, corresponding to the given damage. The course of a vehicle deceleration was captured by the crash meter, while the time-depending course of Renault Laguna vehicle deceleration is shown in Fig. 9.
In Fig. 9 above is recognizable considerable oscillation caused by the natural frequency of the measuring device, by a fixing method of the measuring device, as well as by the oscillation of the measuring point (trunk floor of the vehicle) during the impact. For further evaluation it was therefore necessary to filter out the resulting oscillation, and thus the time-depending course of decel-eration of the given vehicle was obtained (for each vehicle). In Fig. 10 the filtered course for Renault Laguna vehicle is shown.
The time-depending course of deceleration was integrated according to the following formula: where: a(t) -time-depending course of deceleration.
By the mentioned integration the time-depending course of the velocity was obtained. This course was consequently integrated by the following formula: where: v(t) -time-depending course of the velocity.
Consequently, from the obtained data of the path and deceleration a path-deceleration diagram was constructed (during the tests). In Figs. 11, 12 and 13 the individual diagrams for the tested vehicles are shown. For Renault Megane Scenic vehicle, the crash meter broke down and the correct record was not captured. For comparison of the presented diagrams with an older generation of vehicles an analogous procedure with 4 crash tests of a Ford Escort vehicle was performed. It was executed by the company DSD LINZ (Austria) in 1996 [1]. The given courses and impact velocity for a given crash test are shown in Fig. 15.
From the comparison of deceleration courses depending on the deformation depth for the vehicles Ford Escort (year of man-

Conclusion
From the tests performed it is concluded that for the newer generation of vehicles -production year around 2000 it will be more difficult to properly identify the EES of the given vehicle (under conditions where EES exceeds 50 km/h) versus the older generation of vehicles (which were subject of tests -Crash tests DSD LINZ 1996). This is due to the significantly different course of deceleration and, therefore, also due to the course of stiffness of vehicles, at crash velocities above 50 km/h. Such difference is evident also from the comparison of the extent of damage, as shown in Fig. 17.
The significant difference between the vehicles Ford Escort and vehicles tested by the Institute of Forensic Engineering, University of Zilina is reflected also in terms of dependency of a shorter wheelbase and impact velocity (see Fig. 18).   [2]