PSI - Issue 68

Pascal Franck et al. / Procedia Structural Integrity 68 (2025) 119–125 P. Franck et al./ Structural Integrity Procedia 00 (2025) 000–000

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Fig. 2. (a) Material reactions during a multiple amplitude test and (b) testing setup with strain measurement using displacement sensors.

Further, the fracture mechanisms occurring during the MAT were analyzed. Fig. 3 shows two representations of a specimen, that shows a typical fracture pattern for LBL. When looking at the curves of the bone-shaped specimen, the previously described characteristic crack initiation is visible. For almost all specimens a crack in this area appeared throughout the testing procedure. The final fracture of the engineered bamboo can be attributed to further cracks in the thinner testing area of the specimen. As it becomes apparent in the fractographic pictures, the crack initiation was promoted by the nodal areas still recognizable in the LBL material. This can be traced back to the disruption of the straight alignment of the bamboo fibers in the culm wall. In the nodal area, the fibers are dislocated from their course, which leads to the nodal areas being weakening points of the bamboo material.

Fig. 3. Fatigue damage of the laminated bamboo lumber with pronounced destruction in the area of the bamboo node contained in the engineered material.