基于生长轮尺度的早材与晚材机械吸湿蠕变行为及其互作机制

木材蠕变是影响木制品和工程构件质量以及结构设计安全性的一个关键特性。木材在水分-力协同作用下发生的机械吸湿蠕变行为是涉及多因素的复杂问题，其解明的途径在于能够在生长轮尺度上分别弄清楚早材与晚材的“自由缩胀”、“弹性响应”、“普通蠕变”和“机械吸湿效应”4个参量的行为规律与响应机制。本项目以楸木和马尾松木材为材料，集成应用动态力学分析技术、纳米压痕技术以及动态水分吸附分析仪联用白光显微镜成像技术等，在系统表征由水分、力以及机械吸湿效应所引发的变形规律的基础上，通过“水分-力协同作用——早材与晚材发生机械吸湿蠕变的互作方式——生长轮机械吸湿蠕变行为发生机制”关联分析，揭示机械吸湿效应对蠕变行为的促进机理，最终在生长轮尺度上阐明决定木材机械吸湿蠕变的关键因子。研究结论可以丰富和完善木材流变学的基础理论，为工程设计中合理选材、用材提供科学指导，对木结构材料耐久性的研究具有重要的理论指导意义。

The creep behavior of wood is the primary consideration for in-service design of wood used in load-bearing components. When wood is subjected simultaneously to load and moisture variation, the mechano-sorptive creep occurred. To better understand the mechano-sorptive creep, the characteristics and response mechanism of expansion, elastic behavior, pure viscoelastic creep and mechano-sorptive effect should be unraveled for earlywood and latewood at growth ring scale, respectively. In this project, Chinese catalpa (Catalpa bungei C.A.Mey) and Masson pine (Pinus massoniana Lamb.) are selected to investigate the strains resulted from moisture, load and mechano-sorptive effect via dynamic mechanical analysis, nano indentation technique and dynamic vapor sorption with white light microscope imaging technique et al. Moreover, the influence of mechano-sorptive effect in creep behavior was revealed through the correlation analysis of "moisture-load synergy － the interaction mode of mechano-sorptive creep between earlywood and latewood － the response mechanism of mechan-sorptive creep at growth ring scale", as a consequence the primary influence factors for mechano-sorptive creep are determined. The achievements of this project will enrich and improve wood rheology theory, give theoretical guidance for rational selection and use of wood in engineering design, and also provide scientific bases for the durability study of wooden structure materials.