木材干燥流变的研究进展OA

During the conventional drying process,the drying stress,primarily caused by the moisture content gradient and shrinkage anisotropy,is the main driver of wood drying rheology.Additionally,collapse due to capillary tension represents another distinct phenomenon contributing to the rheological behavior of wood during drying.Research on wood drying rheology should include the analysis of collapse phenomena.This study reviewed the characteristics and microscopic response mechanisms of free shrinkage strain,elastic strain,viscoelastic creep,and mechano-sorptive creep that occur during the wood drying process,summarized experimental measurement methods and model prediction methods for these four types of strain and explored the drying rheological characteristics of wood prone to collapse.As a viscoelastic material,the elastic strain generated by drying stress was a major factor causing board cracking,while viscoelastic deformation exhibited hysteresis compared to elastic deformation.Mechano-sorptive creep strain,on the other hand,resulted in irreversible and permanent deformation but could inhibit board cracking.Wood collapse was partially influenced by tensile and compressive stress,affecting the drying rheology.However,the properties and mechanisms of collapse remained unclear.Future research should focus on three key aspects:1)Techniques such as full-field microscopic imaging,nuclear magnetic resonance(TD-NMR),hyperspectral imaging(HSI)and digital image correlation(DIC)should be employed for real-time,in-situ measurement of strain in wood during the drying process.2)This study investigated the microscopic multi-scale structural response mechanisms of wood under stress during drying,focusing on the generation,development,and recovery of various strain types.Particular emphasizing was placed on the response mechanism of mechanical adsorption creep,explaining microscopic deformation from the perspectives of cells,microfibril angles,and chemical bond interactions.3)This study integrated finite element and numerical analysis methods to investigate the rheological development and interaction mechanisms of wood shrinkage and collapse during drying,taking into account the effects of capillary tension and drying stress.