PSI - Issue 34

Alexander Berndt et al. / Procedia Structural Integrity 34 (2021) 105–110 Author name / Structural Integrity Procedia 00 (2019) 000–000 =

108 4

(1)

The SEA of each specimen is determined by calculating the average load over the crush distance per absorbed mass of material (2). = 0 / 0 (2) 3. Experimental Results

The quasi-static compression tests were performed on each set of specimens. Figure 4 shows the crush behavior of an CCF crash tube with 60 ° fiber angle. Figure 4a-b) shows the start of the damage triggering process until shortly after the elastic region. Figure c-e) shows the progressively crushed CCF crash tube. Due to the chamfering of the specimen a local failure is initiated at the start of the crushing process. This leads to a circumferential delamination and axial cracks and therefore, petals are formed (Fig. 5). After bending the petals even further, the petals will fracture caused by the brittle behavior of carbon fibers.

Figure 6a) shows the force-displacement curve of one specimen of each set. The data was chosen based on the best CFE of each specimen set. The best specimen 15-4 has a CFE of 0,83 . Followed by 30-2 with CFE of 0,78 , 45-5 with 0,7, 60 - 2 with 0,67 and 75 -2 with 0,61. Figure 6b) summarizes the SEA average values obtained for all sets of specimens. It shows that the 15 ° fiber stack up has the highest SEA and the highest maximum force absorbed. This is explained by the basics of composite materials. If the loads are applied parallel to the fiber direction, the fiber can absorb less energy compared to a perpendicular fiber angle