Takahashi Akihiro, Yamamoto Naoyuki, Ooka Yu, Toyohiro Toshinobu
Department of Mechanical Engineering, National Institute of Technology, Miyakonojo College, 473-1 Yoshio, Miyazaki 885-8567, Japan.
Architecture, National Institute of Technology, Miyakonojo College, 473-1 Yoshio, Miyazaki 885-8567, Japan.
Materials (Basel). 2022 Mar 22;15(7):2347. doi: 10.3390/ma15072347.
With the crisis awareness of global warming and natural disasters, utilization of local wood has drawn increasing attention in achieving the Sustainable Development Goals (SDGs). It is necessary to investigate the deformation and fracture of the structural tissue in wood in order to improve the safety and reliability of wood application. However, deformation and fracture mechanisms of the structural tissue in each annual ring are unknown. The mechanical characteristics of wood are reflected in the properties of earlywood and latewood. In the present study, microstructural observation and tensile tests were conducted to examine the relationship between the mechanical properties and fracture behavior of latewood in the growth direction in Japanese cedar. Brittle fracture behavior of the latewood specimen was confirmed based on the tensile stress-strain curve and features of the fracture surface. Moreover, two fracture modes, tensile fracture and shear fracture, were recognized. Weibull analysis of tensile strength in each fracture mode was performed to evaluate the reliability and utility of brittle latewood. Lastly, two fracture mechanisms were discussed based on the failure observation findings by a scanning electron microscope.
随着全球变暖和自然灾害危机意识的增强，在实现可持续发展目标（SDGs）的过程中，当地木材的利用受到了越来越多的关注。为了提高木材应用的安全性和可靠性，有必要研究木材中结构组织的变形和断裂情况。然而，每个年轮中结构组织的变形和断裂机制尚不清楚。木材的力学特性体现在早材和晚材的性能上。在本研究中，通过微观结构观察和拉伸试验，研究了日本雪松中晚材在生长方向上的力学性能与断裂行为之间的关系。基于拉伸应力-应变曲线和断口特征，确认了晚材试样的脆性断裂行为。此外，还识别出两种断裂模式，即拉伸断裂和剪切断裂。对每种断裂模式下的拉伸强度进行威布尔分析，以评估脆性晚材的可靠性和实用性。最后，基于扫描电子显微镜的失效观察结果，讨论了两种断裂机制。
