# Investigation of Functionality of Vehicle Crumple Zones Recovered after a Traffic Accident
## 4 Results  
### Analysis of Results Obtained with the Dynamic Models of Distributed Masses  
The elements of the front crumple zone of a Toyota Yaris (year 2007) were chosen as the modelling object (Figure 15). There are many non-genuine spare parts attributable to crumple zone elements produced for this vehicle. This study aimed at verifying the rationale of the use of these elements. During the repair of this vehicle, the mentioned non-genuine crumple zone elements were used, while the longitudinal member was straightened back. Consequently, this kind of repair results in completely different crumple zone parameters. Hence, after the repair works, the car may have substantial hidden, or even life-threatening, changes. Calculations  
Figure 14: 30 mm, 60 mm and specimen with maximum deformations: (**a**)—2 mm square finite element; (**b**)—4 mm finite element; (**c**)—8 mm finite element. Figure 15: Toyota Yaris crumple zones: deformed after crash (**a**), recovered after crash (**b**), crumple zone elements for energy absorption (**c**). using the SMUG94 software developed at the Department of Transport Engineering at Kaunas University of Technology were carried out at two different velocities: 30 km/h and 64 km/h. We chose 64 km/h as it is the limit velocity at which the driver and crew would still survive in the event of a front collision with a fixed obstacle. The crumple zone parameters were determined by measuring the cross-sections of crumple zone elements. Limit loads were determined according to the loss of stability by the crumple zone. The initial calculation data are presented in Table 2.  
After definition of the methodology of grouping the elements into crumple zones and determination of the crumple zone parameters \(m_{i}\), \(C_{i}\), \(k_{i}\), \(F_{crit}\), \(x_{\lim}\), it became possible to model the process of deformation of the entire crumple zone during impact. Three calculation variants were performed: variant 1--standard parameters of all three zones; variant 2--standard parameters of the 2 nd and 3 rd zones, 1 st zone consisting of non-genuine parts; variant 3--standard parameters of the 3 rd zone, 1 st zone consisting of non-genuine parts, 2 nd zone rigidity lower than 30%. Variant 3 was selected because, in cases where the 1 st zone needs replacement, the 2 nd zone is usually also subjected to deformations. The results obtained when modelling a traffic accident with a Toyota Yaris at initial velocity with obstacle equal to 64 km/h are presented in Figure 16.  
In this case, the overload values were already hazardous to the car crew. The determined head injury criteria (HIC) [50; 51] values in all three cases of crumple zone configuration were: in case of standard crumple zone elements--HIC = 640, non- genuine 1 st zone parts--HIC = 607, and the third variant--HIC = 700. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Characteristics** & **Zone 1** & **Zone 1\({}^{*}\)** & **Zone 2** & **Zone 3** & **Zone 4 (i=4;5)** \\ \hline \(m_{i}\) & 30 & 28 & 80 & 1150 & 75 \\ \(C_{i}\) & 280 & 120 & 790 & 1680 & 38; 50 \\ \(k_{i}\) & 0.52 & 0.48 & 2.36 & 15.32  
Investigation of the Effect of Quasi-Static Buckling and Geometric Deviation of the Damaged Crumple Zone on the Specim Deformation  
The analysis of results generated by the dynamic models has shown that the descriptions of characteristics of crumple zone elements need to be adjusted. The geometry and structure of the modelled element corresponded to the specimen P1 of the crumple zone fragment of a Toyota Yaris used during the quasi-static in situ buckling experiments. The cross-section area of the specimen was equal to 256 mm\({}^{2}\).