## 3 Results and Discussion
### Validation of the Simulation Results and Failure Modes
By further increasing the drawing depth up to 25 mm, the deletion of cohesive elements propagated accordingly to reach the flange area. The laminate lost support from the tool first in the side wall area when the laminate was deep-drawn into the die. With further punch displacement, the flange area of the laminate flowed inwards. Plastic deformation and relative sliding could occur when the adhesion strength between layers was weakened due to the high temperature [37]. As no fibre fracture criterion was defined in the material modelling, the simulation results showed deviation from the experimental ones. Thus, wrinkling of organosheet RG, but not of the fibre fracture, in simulated conditions could be successfully validated by the experiments. By analysing the stress and strain evolution of the inner and outer steel sheets at a punch displacement of 40 mm, it can be seen that the stress evolution of inner and outer steel sheets was homogeneous, which is a different result from the anisotropic organosheet core RG (Figure 22b). Moreover, the strain evolution of RG was localized in the 0\({}^{\circ}\), 45\({}^{\circ}\), and 90\({}^{\circ}\) directions in the flange area (see Figure 22c). As was different from the experimental results in terms of the strain evolution of the cover sheets, the simulation showed the anisotropic strain evolution of the inner and outer steel sheets, which was due to the anisotropic behaviour of the core RG. In contrast, the experimental results showed more isotropic strain evolution in Figure 22c, which might have been due to the fibre fracture in the warp and weft directions. In addition, the flow behaviour of the cover sheets in the 0\({}^{\circ}\) (warp) and 90\({}^{\circ}\) (weft) directions at the flange and die edge area changed. Thus, the influence of anisotropic RG was minimized and the nature of TS275 itself dominated at 200 \({}^{\circ}\)C. To interpret the different strain evolution results between the experiments and the simulation, cross-sectional strain analysis was carried out as shown in in Figure 23a. As can be seen, the simulated strain evolution of the outer steel sheet in FML\({}^{01}\)-RG0.5 at 0\({}^{\circ}\) and 90\({}^{\circ}\) was significantly lower than that oneat 45\({}^{\circ}\) and at 200 \({}^{\circ}\)C, which was obviously different from the experimental one in Figure 18b. However, the simulation result of the monolithic steel sheet TS275 matched with the experimental one very well. In addition, the force evolution indicated that the simulation result of monolithic RG at RT and FML\({}^{01}\)-RG0.5 at 200 \({}^{\circ}\)C deviated significantly from the experimental results at drawing depths of 10 mm and  
Figure 21: Simulation results of core RG in FML\({}^{01}\)-RG0.5 under the different interaction conditions in Table 7 at strokes of 25 mm and 40 mm. 15 mm, respectively (Figure 23b). The reason may be the fact that the fibre degradation and damage criterion were not implemented in the simulation model. However, the simulation results coincided with the experimental result of monolithic TS275 very well. Based on the current simulation techniques, further modelling and simulation studies in terms of damage initiation and evolution of the organosheets are necessary, and will be performed in the extension of the current project. Moreover, the influence of temperatures and strain rate on the material properties could also be taken into account and embedded into the simulation model if necessary. Finally, the thickness distribution and the macro-defects of the deep-drawn FML at different forming temperatures were qualitatively investigated. The thickness distribution was homogeneous at RT in the FML\({}^{01}\)-RG0.5 (Figure 24a) and remained uniform while forming at 200 \({}^{\circ}\)C, along with substantially improved formability, as shown in Figure 24b.