*3.1. Model Validation of the Reference Model*

Figure 8 shows a comparison of the deformation and failure behaviour of impactloaded CFRP beams with different interface modifications (design A) based on both experimental and numerical analyses. In the case of no interface modification *κ<sup>i</sup>* = 1, the specimen fails brittle and central. This is well-predicted by the simulation. When the interfacial property is weakened (*κ<sup>i</sup>* = 0.3), a delamination failure occurs as initial failure mode on only one side of the specimen with a subsequent fibre failure. This sequence is not predicted accurately by the simulation. The model predicts a symmetrical delamination failure on both sides of the specimen, which is due to the assumed perfect symmetry. Nevertheless, this FEA model can be used to investigate the influence of the interface design on the structural behaviour since the key failure modes are captured by the model.

**Figure 8.** (**a**) Images of high-speed camera during the three-point bending test for two different interface modification concepts [10] and (**b**) corresponding simulation images.
