PSI - Issue 37

672 Behzad V. Farahani et al. / Procedia Structural Integrity 37 (2022) 668–675 Behzad V. Farahani et al./ Structural Integrity Procedia 00 (2021) 000 – 000 • = 9.8 × 10 3 ( 2 ⁄ ) , gravitational constant; • ℎ = The vertical movement of the vehicle centre of gravity during a rollover test. The total energy , , shall be distributed among the bays of the superstructure in the proportions of their masses: = (5) In which, is the absorbed energy by the i th bay and is its mass. The minimum energy required to be absorbed by the body section ( ) is the sum of the energy of the bays comprising the body section. Considering, = 15.6 ( ) , = 1.76 ( ) and ℎ = 9.25 × 10 2 ( ) , the energy can take the following value: (6) However, the internal energy must be computed from the numerical and experimental analyses and then compared to the solution proposed by R66 standard regulation, Equation (6). Thus, it will be feasible to evaluate whether the studied structure has the potential to pass the ECE R66 or it requires some improvements. 3. Analysis and results The bus section has been manufactured and then it was experimentally tested according to the requirements proposed by the R66 standard regulation for rollover tests. Figure 5-a) depicts the tested bus section with the loading mechanism presented in Figure 5-b). Regarding the residual space, a reinforced wood box has been designed, following the dimensions shown in Figure 3-b), and setup in the bus section to be able to accurately monitor the displacement variation. The load was applied through a mechanical mechanism by a Tirfor winch and chains with the angle specified in Figure 3-a) and the displacement was measured with a displacement sensor. A load cell was installed in order to measure the applied load. The experimental test was performed and the force-displacement variation was obtained at the loading position as presented in Figure 6-a). The bus section has been numerically solved using FEM formulations simulated in ABAQUS©. The material properties were used as reported in Table 1. The plastic behavior of both materials was considered in the numerical analyses as experimentally obtained by the authors and presented in Figure 2. The essential and natural boundary conditions were defined according to the experimental conditions, see Figure 5-c). The finite element mesh consists of a total number of 934346 nodes and 1088606 elements. Different types of elements were used to build the mesh including linear hexahedral elements of type C3D8, linear wedge elements of type C3D6 and linear tetrahedral elements of type C3D4. The numerical simulation was performed using a dynamic explicit scheme using a mass scaling with a target time increment of = 5 × 10 −7 ( ) considering nonlinear geometrical effects and material nonlinearity. For the chassis structure, all welded connections were built by TIE constraints to meet the experimental conditions. Regarding the rest of connectio ns in the roof and lateral sides’ components, all connections between profiles were defined as a general contact. The force application mechanism was followed as shown in Figure 5-c) with a magnitude force of = 7 ( ) . Therefore, it was applied in accordance with the configuration depicted in Figure 3-a) and Equation (2). The whole structure was fixed from the bottom side of the chassis as shown Figure 5 c). 5 = 106.06 ( ) ; = 11.97 ( ) .