In-situ characterization of the compression failure behavior of Chinese fir wood by using micro-CT and digital volume correlation analysis

Abstract

Chinese fir (Cunninghamia lanceolata) wood has been widely used in structural applications owing to its excellent machinability and rapid growth. A comprehensive understanding of its mechanical behavior, particularly under compression loading, is critical for ensuring the reliability and safety of structural components. This study explored the failure behavior of Chinese fir wood under axial, radial, and tangential compression using micro-computed tomography (micro-CT) and digital volume correlation (DVC) techniques. The results revealed that Chinese fir wood exhibited high compressive stiffness under axial compression, with displacement and strain localized around inherent defects. Under radial compression, significant strain concentration was observed at earlywood tracheid lumens and growth ring interfaces, which acted as primary sites for strain localization, initiating localized failure and subsequent deformation propagation. In tangential compression, the wood demonstrated moderate compressive strength with relatively uniform deformation, although stress concentration persisted in weaker regions, particularly within earlywood tracheids. These earlywood tracheids, characterized by thinner walls and larger lumens, played a pivotal role in stress concentration and failure propagation, accelerating localized damage. This study underscores the anisotropic mechanical behavior of Chinese fir wood under compression in three directions and elucidates the associated damage evolution mechanisms, providing a theoretical foundation for evaluating its mechanical properties and guiding structural optimization.