三种加载方向下云杉静动态力学性能研究  

RESEARCH ON STATIC AND DYNAMIC MECHANICAL PROPERTIES OF SPRUCE WOOD BY THREE LOADING DIRECTIONS

作　　者：钟卫洲[1] 宋顺成[2] 黄西成[1] 郝志明[1] 谢若泽[1] 陈刚[1] 

机构地区：[1]中国工程物理研究院总体工程研究所,绵阳621900 [2]西南交通大学力学与工程学院,成都610031

出　　处：《力学学报》2011年第6期1141-1150,共10页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家重点基础研究发展计划(2010CB832700);国家自然科学基金(50874095)资助项目~~

摘　　要：利用INSTRON和Hopkinson压杆对含水率为12.72%,密度为413 kg/m^3云杉木材试件沿顺纹、横纹径向和横纹弦向进行准静态和动态压缩实验,获得了云杉木材3个方向的抗压模量、准静态压缩应力应变曲线和3种应变率下的动态应力应变曲线.结果表明云杉木材沿顺纹方向加载破坏形式表现为木材纤维轴向屈曲、褶皱;横纹径向和弦向加载失效行为表现为木材纤维间的滑移破坏.云杉顺纹方向抗压弹性模量最大,分别约为横纹径向抗压弹性模量的21倍和横纹弦向抗压弹性模量的32倍;横纹径向和弦向准静态压缩屈服应力基本相等,试件沿顺纹方向准静态压缩屈服应力约为横纹径向和弦向屈服应力的9倍;动态压缩屈服强度具有率敏感性,在应变率为500～1 000 s^(-1)动态压缩实验中顺纹、横纹径向和弦向动压屈服强度均随着应变率的增加而显著提高.同时对不同方向压缩下木材胞壁失效行为进行了理论分析,表明产生完全压缩失效的平均极限载荷与胞壁屈服强度、胞元结构和产生的褶皱长度相关.Quasi-static and dynamic compression experiments of spruce wood along axial, radial and tangential loading directions are implemented by INSTRON and Hopkinson pressure bar equipments. Average moisture content and density of the spruce specimens are 12.72 % and 413 kg/m3. Compression modulus and curves of quasi-static compression stress versus strain are gained by static compression experiment. And the relation of dynamic stress versus strain is obtained by dynamic compression experiments with three strain rates. The experiment results show that the failure modes of spruce specimens are fiber buckling and wrinkle when loading direction is along the grain. When loading direction is along radial or tangential across to the grain, the failure modes is wood fiber slippage and delamination. Axial compression modulus is about twenty-one times as that of radial across to the grain, and about thirty-two times as that of tangential across to the grain. Axial quasi-static compression yield strength is about nine times as that of radial and tangential across to the grain. The radial and tangential quasi-static compression yield strengths are almost equal. Dynamic compression yield strength of spruce wood is sensitive to strain rate. The axial, radial and tangential dynamic compression yield strengths increase greatly when strain rate is from 500 to 1000 s-1. In addition, theory analytic solution to single wood cell failure under different direction compression is carried out. The obtained expression shows that the mean limit loading is relative to yield stress, cell structure dimension and wrinkle length for complete wrinkle cases.

关 键 词：云杉 力学性能 正交各向异性 HOPKINSON压杆 压缩实验 

分 类 号：O344.3[理学—固体力学]