木材裂纹尖端应力场的有限元分析和开裂方向预测  

Analysis of Stress Field Near Crack Tip Using Finite Element Method and Prediction of Cracking Direction for Wood Sample with Crack

作　　者：邵卓平[1] 童永耀[2] 盛宏玉[2] 牛忠荣[2] 董宏敢[1] 

机构地区：[1]安徽农业大学林学与园林学院,合肥230036 [2]合肥工业大学土木工程学院,合肥230009

出　　处：《林业科学》2010年第10期108-113,共6页Scientia Silvae Sinicae

基　　金：国家自然科学基金项目(30571452);安徽农业大学创新团队资助

摘　　要：以鱼鳞云杉木材三点弯曲试件为例,应用ABAQUS有限元软件分析裂纹体与木材顺纹向倾角分别为90°,60°,30°,0°时的应力场,并采用"切向比正应力准则"对裂纹的启始开裂方向进行预测。结果表明:1)以裂尖为中心作径向平面,4种裂纹体试件的最大Mises应力所在的径向线均沿着木材的顺纹理方向;2)在除去裂尖奇异点以外的一个较大区域中,垂直裂纹表面的拉应力σY和平行裂纹表面的拉应力σX的比值σY/σX几乎是一个常数,在1～5之间;3)无论初始裂纹与木材顺纹向的夹角如何,其裂尖处的切向比正应力R珔均在顺纹方向上最大,理论预测和试验结果均表明裂纹将折向顺纹方向启裂。最后讨论木细胞间的低界面强度对木材的增韧作用。Taking SEB samples of spruce（Picea asperata） for instance,the finite element software of ABAQUS was used to analyze the stress field of the samples,when the obliquity between the wood crack and the grain of wood were 90°,60°,30°,0° respectively,＂tangential normal stress intensity factor ratio criterion＂was applied to predict the direction of the crack. The results showed the direction of the maximum Mises stress of four samples was along the grain of the wood when drawing a radial plane centered around the crack tip. It is also shown that the ratio of the tensile stress perpendicular to the crack（σY） to the tensile stress parallel to the crack（σX） is approximately a constant within 1 ～ 5 in a large area around crack tip but except the singular point. No matter what is the angle of the initial crack to the grain of wood,the tangential normal stress intensity factor ratio（R^-） of the crack tip over the direction of the grain was the largest. Therefore,the initial crack direction along the grain had been verified either by theoretical prediction or by experiment. The role of toughening of low-interfacial strength between wood cells has been discussed.

关 键 词：木材断裂 有限元 应力场 开裂方向预测 

分 类 号：S781.29[农业科学—木材科学与技术]