PSI - Issue 80

Hideaki Katogi et al. / Procedia Structural Integrity 80 (2026) 462–470 Hideaki Katogi/ Structural Integrity Procedia 00 (2025) 000–000

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1. Introduction Recently, the recycling process of constituent material is very important for sustainable development goals. Some companies must be considered about recycling process of constituent materials of many products and structures such as building, clothing, automobile and so on. There is natural fiber reinforced biocomposite materials using biopolymers. The life cycle assessment of constituent material using the biocomposite material is lower than that of constituent material using petroleum based material. The natural fiber as reinforcement has high specific tensile strength. The natural fiber has good fatigue and creep performances [1,2] for constituent material of new products. The fatigue strength at 10 6 cycles of the natural fiber was about 50 % of the ultimate strength. So, mechanical properties of the biocomposite material using natural fiber should be investigated for new constituent materials. Nakagaito et al. [3] reported on flexural stress of sudachi residue-derived pulp pate for biocomposite material. The flexural stress of sudachi residue-derived pulp pate was about 230 MPa. Tokoro et al. [4] reported about fabrication of biocomposite material using poly(lactic acid) resin and bamboo fiber. The biocomposite material using poly(lactic acid) resin and bamboo fiber was fabricated by injection molding and a twin-screw extruding machine. Cho et al. [5] reported about fabrication process of polyacrylonitrile blending film with biodegradable shellac resin. The surface of polyacrylonitrile blending film with biodegradable shellac resin 10 wt% became smooth after fabrication process. Kimura et al. [6] reported on the effect of degumming time on impact property of plain-woven silk fabric reinforced composite material. The izod impact value of the plain-woven silk fabric reinforced composite material was about 150 kJ/m 2 when degumming time was about 30 min. The impact property of plain-woven silk fabric reinforced composite material has superior performance. There are many papers about mechanical properties of biocomposite material and natural fiber [7-24]. But the length of plant fiber as natural fiber is short. Thomason [25] reported about evaluation of cross-section shape of plant fiber for biocomposite materials. The cross section of plant fiber can be better estimated by an ellipse shape. So, the yarn structure using plant fiber has been used for optimization of the constituent material. Ren et al. [26] reported about tensile property of unidirectional reinforced biocomposite material using flax sliver. The tensile strength of unidirectional reinforced biocomposite material using flax sliver was about 240 MPa. The tensile property of the unidirectional reinforced biocomposite material using flax sliver was good performance for alternative material of aluminium alloy. Ogihara et al. [27] reported on the effect of fiber direction on tensile property of unidirectional bamboo fiber reinforced poly(butylene succinate) resin. Tensile strength and young’s modulus of unidirectional bamboo fiber reinforced poly(butylene succinate) resin were about 96 MPa and about 14 GPa when the fiber volume fraction was 50 wt%. But the tensile property of unidirectional bamboo fiber reinforced poly(butylene succinate) resin in the fiber direction was higher than that of unidirectional bamboo fiber reinforced poly(butylene succinate) resin in the transverse direction. Matsumoto et al. [28] reported about fabrication and mechanical properties of ramie yarn reinforced biocomposite material using cellulose nanofiber for 3D printing of new products. The false-untwisting technology in the dip-coating process could be enhanced the load-transfer effect of cellulose nanofibers in biocomposite material. The paper about fatigue property of jute sliver reinforced biocomposite material was published for long-term safety [29]. The fatigue strength at 10 5 cycles of the unidirectional jute sliver reinforced biocomposite material was about 50% of the ultimate strength. Also, Katogi et al. [30] reported on fatigue property of unidirectional jute spun yarn reinforced biocomposite material. The fatigue strength at 10 6 cycles of the unidirectional jute spun yarn reinforced biocomposite material was about 55% of the ultimate strength. Furthermore, there is paper about effect on matrix ductility on fatigue property of unidirectional jute spun yarn reinforced biocomposite materials for new product of sustainable development goals [31]. The fatigue life of biocomposite material using poly(butylene succinate) resin was longer than that of biocomposite material using poly(lactic acid) resin. Above mentioned, the fatigue property of unidirectional jute spun yarn reinforced biocomposite material has good performance for safety. But many products must be considered for anti-impact property of constituent material. So, the effect of loading speed on tensile property of natural plant yarn reinforced biocomposite material must be investigated for safety and manufacturing of new products. In this study, tensile properties of a single flax yarn reinforced biocomposite materials using poly(lactic acid) and shellac under loading speed were investigated for safety of products. Also, the tensile test of a single flax yarn was