Deformation properties of Finnish spruce and pine wood in tangential and radial directions in association to high temperature drying?Part IV. Modelling

详细信息    查看全文

• 作者：A. Hanhij?rvi
• 刊名：Holz als Roh- und Werkstoff
• 出版年：2000
• 出版时间：November 2000
• 年：2000
• 卷：58
• 期：4
• 页码：211-216
• 全文大小：128 KB

文摘

) and Scots pine (Pinus sylvestris) wood under conditions relevant in the high temperature drying process. The programme included tension experiments on perpendicular specimens at temperatures 95 ¡ãC–125 ¡ãC. Based on the experiments, a constitutive model to describe the behaviour was developed for use in numerical simulation of drying stresses and is reported in this paper. The model takes into account all the needed strain terms: hygroexpansion (shrinkage, swelling), hygrothermal, elastic, viscoelastic and mechano-sorptive strains. Elastic and viscoelastic strains are modelled jointly as generalised Kelvin material, using the time–temperature–moisture-content superposition principle. Mechano-sorptive creep is modelled with a series of modified `mechano-sorptive Kelvin elements', in which a part of the strain is irrecoverable unless the direction of the acting stress changes.