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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Table 1. Load levels of the constant amplitude tests with the number of cycles to failure reached. Maximum stress σ max (MPa) Number of cycles to failure N f 87.55 (Avg. tensile strength) 1 65 6,500 60 66,000 55 185,000 50 375,000 45 2,000,000 35 2,000,000

4. Conclusion and outlook The material tests presented have shown that laminated bamboo lumber has outstanding tensile properties. The determined quasi-static tensile strength of about 90 MPa is equal to the strength of spruce, a commonly used wood species in e.g., civil engineering. Further, the desired 2 million cycles without failure were achieved at several load levels, one of which was at 45 MPa, about 50% of the material's tensile strength. At the higher load levels, the material showed a stronger plastic response with the typical crack highlighted in the curve of the bone-shaped specimens. However, after the initial crack development, the LBL withstood the loads for some time until the test area of the specimen was destroyed. The applied digital image correlation was capable of recording the occurring material reactions and localizing high loaded areas in the LBL. First insights on the fracture mechanisms could be gathered and the nodal areas of the bamboo still contained in the LBL could be identified as weakening points that tend to promote fracture and crack initiation. At this time, the fatigue investigations of LBL are ongoing. The CATs are conducted on further load levels. In addition, the influence of the surrounding environment should be investigated. Therefore, the tests should be carried on under elevated temperatures and different relative humidity levels. Especially, the latter should have a major influence on the hygroscopic bamboo material. Further, other measuring technologies should be evaluated and different types of testing procedures (e.g., different load ratios) should be tested, to get an overview as comprehensive Al-Rukaibawi, L. S., Kachichian, M., Károlyi, G., 2024. Mechanical properties of laminated bamboo lumber N-finity according to ISO 23478 2022. Journal of Wood Science 70, 1. https://doi.org/10.1186/s10086-023-02115-z Dauletbek, A., Li, H., Lorenzo, R., Corbi, I., Corbi, O., Ashraf, M., 2022. A review of basic mechanical behavior of laminated bamboo lumber. Journal of Renewable Materials 10, 273–300. https://doi.org/10.32604/jrm.2022.017805 Isukuru, E. J., Ogunkeyede, A. O., Adebayo, A. A., Uruejoma, M. F., 2023. Potentials of bamboo and its ecological benefits in Nigeria. Advances in Bamboo Science 4, 100032. https://doi.org/10.1016/j.bamboo.2023.100032 Kelkar, B. U., Shukla, S. R., Nagraik, P., Paul, B. N., 2023. Structural bamboo composites: A review of processing, factors affecting properties and recent advances. Advances in Bamboo Science 3, 100026. https://doi.org/10.1016/j.bamboo.2023.100026 Mishra, G., Giri, K., Panday, S., Kumar, R., Bisht, N. S., 2014. Bamboo: potential resource for eco-restoration of degraded lands. Journal of Biology and Earth Science 4, 130–136. Qiu, Z., Wang, J., Fan, H., Li, T., 2020. Anisotropic mechanical properties and composite model of parallel bamboo strand lumbers. Materials Today Communications 24, 101250. https://doi.org/10.1016/j.mtcomm.2020.101250 Verma, C. S., Sharma, N. K., Chariar, V. M., Maheshwari, S., Hada, M. K., 2014. Comparative study of mechanical properties of bamboo laminae and their laminates with woods and wood based composites. Composites Part B: Engineering 60, 523–530. https://doi.org/10.1016/j.compositesb.2013.12.061 Wakchaure, M. R. Kute, S. Y., 2012. Effect of moisture content on physical and mechanical properties of bamboo. Asian Journal of Civil Engineering 13, 753–763. Zhang, H., Li, H., Li, Y., Xiong, Z., Zhang, N., Lorenzo, R., Ashraf, M., 2021. Effect of nodes on mechanical properties and microstructure of laminated bamboo lumber units. Construction and Building Materials 304, 124427. https://doi.org/10.1016/j.conbuildmat.2021.124427 as possible. References