﻿ 木材裂纹尖端应力场的有限元分析和开裂方向预测
 林业科学  2010, Vol. 46 Issue (10): 108-113 PDF
DOI: 10.11707/j.1001-7488.20101018
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#### 文章信息

Shao Zhuoping, Tong Yongyao, Sheng Hongyu, Niu Zhongrong, Dong Honggan

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

Scientia Silvae Sinicae, 2010, 46(10): 108-113.
DOI: 10.11707/j.1001-7488.20101018

### 作者相关文章

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

Analysis of Stress Field Near Crack Tip Using Finite Element Method and Prediction of Cracking Direction for Wood Sample with Crack
Shao Zhuoping1, Tong Yongyao2, Sheng Hongyu2, Niu Zhongrong2, Dong Honggan1
1. School of Forestry and Landscape Architecture, Anhui Agricultural University Hefei 230036;
2. School of Civil Engineering, Hefei University of Technology Hefei 230009
Abstract: 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.
Key words: wood fracture    finite element method    stress field    crack direction prediction

1 材料与方法 1.1 材料与基础数据

 图 1 测试木材弹性常数的6种试样 Figure 1 Six samples of wood for testing elastic modulus

1.2 断裂分析模型

 图 2 SEB试件的裂纹体与纤维方向 Figure 2 Crack and fiber orientation of SEB sample

 图 3 用于有限元分析的裂尖1/4奇异单元网格 Figure 3 Arrangement of the quarter point elements at the crack tip used in the finite element simulation
2 结果与分析 2.1 裂纹尖端Mises应力场

 图 4 4种裂纹试件的裂尖附近的Mises应力场云(β为裂纹与顺纹向的夹角) Figure 4 The Mises stress nephogram around crack tip of four SEB species(β is angle between crack and fibre)
2.2 开裂方向预测

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 (2)

 (3)
 图 5 裂纹尖端附近的切向正应力示意 Figure 5 Illustration of trangential normal stree surrounding the crack tip

3 对木材界面强度与强韧性的讨论

 图 6 裂尖正前方与垂直裂纹面张应力σY和平行裂纹面张应力σX的分布趋势 Figure 6 The distribution of tensile stress perpendicular to crack (σY) and tensile stress parallel to crack (σX) from crack tip to up
 图 7 木材界面阻止裂纹横纹扩展示意 Figure 7 Illustration of wood interface arrest crack spreading across the grain

4 结论

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