PSI - Issue 37

Behzad V. Farahani et al. / Procedia Structural Integrity 37 (2022) 668–675 Behzad V. Farahani et al./ Structural Integrity Procedia 00 (2021) 000 – 000

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a)

b)

c) e) Figure 5. a) Experimental configurations on the bus section, b) loading mechanism, c) numerical model respecting the boundary conditions, d) profiles involved for the residual space measurement and e) the nodes allocated on the profiles to measure the displacement for the residual space . Regarding the residual space concept, it was virtually considered in the numerical modelling. As shown in Figure 5-d), three profiles were involved in this calculation highlighted in red in the corresponding figure. These three profiles are the main parts, which will be in touch with the residual space upon loading. Thus, three points were assigned to these profiles with an altitude of 950 ( ) to the chassis top surface according to the R66 standard, c.f. Figure 5-e). Hence, it is feasible to monitor the displacement variation on these three points. As mentioned before, the maximum allowable magnitude displacement on any of these points shall not exceed = 150 ( ). The numerical analysis was performed and the force displacement was obtained on the loading position as presented in Figure 6-a). Besides, the force/displacement variation on the selected points regarding the residual space was obtained as presented in Figure 6-b). A closer look to the obtained results, it can be stated that the results would be valid upon point with a magnitude displacement of = 269 ( ) related to the applied force of ≅ 4.5 ( ) . The results show that the structure behaved differently after point P due to the unforeseen structural response in the experimental test. It can be inferred that some parts of the structure might already been yielded and it led to the damage and failure occurrence. Consequently, the structural integrity has been significantly affected and therefore the force displacement curve dropped. However, it was possible to compute the internal energy from the force-displacement curves until point P for both numerical and experimental analyses as reported in Table 2. Although both FEM and experimental results on internal energy are very far from the R66 standard solution, there is a reasonable agreement between the experimental and FEM solution. In can be concluded that the numerical modeling conformed to experimental conditions in terms of boundary conditions and connection definitions. d)