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孔洞对木梁弯曲应变分布影响的试验研究

温宇鑫 赵健 赵东

温宇鑫, 赵健, 赵东. 孔洞对木梁弯曲应变分布影响的试验研究[J]. 北京林业大学学报, 2017, 39(11): 106-113. doi: 10.13332/j.1000-1522.20170221
引用本文: 温宇鑫, 赵健, 赵东. 孔洞对木梁弯曲应变分布影响的试验研究[J]. 北京林业大学学报, 2017, 39(11): 106-113. doi: 10.13332/j.1000-1522.20170221
WEN Yu-xin, ZHAO Jian, ZHAO Dong. Experimental study on the effects of holes on bending strain distribution of wood beams[J]. Journal of Beijing Forestry University, 2017, 39(11): 106-113. doi: 10.13332/j.1000-1522.20170221
Citation: WEN Yu-xin, ZHAO Jian, ZHAO Dong. Experimental study on the effects of holes on bending strain distribution of wood beams[J]. Journal of Beijing Forestry University, 2017, 39(11): 106-113. doi: 10.13332/j.1000-1522.20170221

孔洞对木梁弯曲应变分布影响的试验研究

doi: 10.13332/j.1000-1522.20170221
基金项目: 

国家自然科学基金项目 11502022

中央高校基本科研业务费专项 2015ZCQ-GX-02

详细信息
    作者简介:

    温宇鑫,博士生。主要研究方向:木材力学性能与无损检测。Email:when0714@163.com  地址:100083 北京市海淀区清华东路35号北京林业大学工学院

    责任作者:

    赵东,教授,博士生导师。主要研究方向:工程力学与仿真、农林机械。Email:zhaodong68@bjfu.edu.cn  地址:同上

  • 中图分类号: TP391

Experimental study on the effects of holes on bending strain distribution of wood beams

  • 摘要: 为了研究孔洞对木梁弯曲应变分布的影响,采用数字图像相关法进行了无疵木梁和含孔洞木梁的四点弯曲试验,分析了3种不同的孔洞位置(孔洞位于中心、受压区和受拉区)对木梁弯曲应变分布的影响,探讨了中性轴位置的偏移规律。结果表明:在极限载荷时,3种不同孔洞位置的木梁,其压应变区域均大于拉应变区域,其中孔洞位于受压区时木梁的压应变区域最大,孔洞位于中心时次之,孔洞位于受拉区时最小。并且在整个加载过程中,中性轴会随着载荷的增大向木梁下缘偏移,孔洞位于受压区时中性轴的偏移距离最大,孔洞位于中心时次之,孔洞位于受拉区时最小。在此基础上,依据平截面假定和弹塑性理论的Hoffman屈服准则,初步分析了含孔洞木梁弯曲应变分布和中性轴偏移规律的机理。研究结果为进一步从理论上定量推导含孔洞木梁的弯曲应变和应力计算公式提供了依据。

     

  • 图  1  试件

    Figure  1.  Test specimens

    图  2  试验装置示意图

    Figure  2.  Experiment instruments

    图  3  4组木梁弯曲变形的载荷-挠度曲线

    Figure  3.  Plot of load versus deflection for four groups of wood beams in bending deformations

    图  4  木梁的研究区域

    Figure  4.  Area of interest for wood beam

    图  5  不同载荷时无疵木梁的轴向应变云图

    Figure  5.  Longitudinal strain fields for clear beam under different loads

    图  6  不同载荷时孔洞位于中心的木梁的轴向应变云图

    Figure  6.  Longitudinal strain fields for beam with a hole located at center under different loads

    图  7  不同载荷时孔洞位于受压区的木梁的轴向应变云图

    Figure  7.  Longitudinal strain fields for beam with a hole located at compression zone under different loads

    图  8  不同载荷时孔洞位于受拉区的木梁的轴向应变云图

    Figure  8.  Longitudinal strain fields for beam with a hole located at tension zone under different loads

    图  9  弹塑性阶段含孔洞木梁截面的应变和应力沿梁高分布

    b为木梁宽度, mm; h为木梁的高度, mm; c为塑性变形区的高度, mm; d为孔径, mm; e为孔洞下缘到木梁下缘的距离, mm; y0为中性轴到木梁下缘的距离,mm。εc为受压区的应变, εt为受拉区的应变, σt为拉伸屈服强度, MPa,σc为压缩屈服强度, MPa。

    Figure  9.  Strain and stress distribution along height of beam containing holes during elastic-plastic stage

    b is width of beam (mm), h is height of beam (mm), c is height of plastic deformation region (mm), d is diameter of hole (mm), e is distance from the bottom of hole to the bottom of beam (mm), and y0 is distance from neutral axis to bottom of beam (mm). εc is strain in compression zone, εt is strain in tension zone, σt is tensile yield strength (MPa), σc is compressive yield strength (MPa).

    表  1  4组木梁的极限载荷、抗弯强度和抗弯弹性模量

    Table  1.   Ultimate load, bending strength and modulus of elasticity in bending for four groups of wood beams

    试件编号
    Specimen No.
    孔洞位置
    Location of hole
    极限载荷
    Ultimate load(Fmax) /kN
    抗弯强度
    Bending strength (σb) /MPa
    y0/mm Em/MPa Ec/MPa
    S0 3.06 90.19 9.29 29.33 30.13(2.73%)
    S1 中心Center 2.67 80.01 8.83 25.05 25.79(2.95%)
    S2 受压区Compression zone 2.38 71.36 5.91 26.22 25.47(2.86%)
    S3 受拉区Tension zone 2.93 87.90 9.37 26.92 27.07(0.56%)
    注:y0为极限载荷时中性轴到木梁下缘的平均距离。Em为抗弯弹性模量测量值,Ec为根据应变沿梁高分布计算得到的抗弯弹性模量,括号内数值为计算值Ec相对于测量值Em的相对误差。Notes: y0 is average distance from neutral axis to bottom of beam at ultimate load, Em is measured modulus of elasticity in bending, Ec is calculated modulus of elasticity in bending based on strain distribution along depth of beam. There are relative errors between Ec and Em in brackets.
    下载: 导出CSV

    表  2  不同载荷时无疵木梁的中性轴位置与压应变区域和拉应变区域的面积

    Table  2.   Location of neutral axis and area of compressive and tension strain region for clear beam under different loads

    载荷阶段
    Load stage
    载荷值
    Load/kN
    y0/mm Ac/AI At/AI Ac/At
    25%Fmax 0.76 10.63 0.47 0.53 0.88
    50%Fmax 1.52 10.49 0.48 0.52 0.91
    75%Fmax 2.28 9.97 0.51 0.49 1.01
    Fmax 3.06 9.29 0.54 0.46 1.15
    注:Ac为压应变区域的面积,At为拉应变区域的面积,AI为研究区域的面积。Ac is area of compressive strain region, At is tension strain region, AI is area of area of interest. Same as below.
    下载: 导出CSV

    表  3  不同载荷时孔洞位于中心的木梁的中性轴位置与压应变区域和拉应变区域的面积

    Table  3.   Location of neutral axis and area of compressive and tension strain region for beam with a hole located at center under different loads

    载荷阶段
    Load stage
    载荷值
    Load/kN
    y0/mm Ac/AI At/AI Ac/At
    25%Fmax 0.67 11.10 0.44 0.56 0.80
    50%Fmax 1.34 10.92 0.45 0.55 0.83
    75%Fmax 2.01 10.18 0.49 0.51 0.96
    Fmax 2.67 8.83 0.55 0.45 1.27
    下载: 导出CSV

    表  4  不同载荷时孔洞位于受压区的木梁的中性轴位置与压应变区域和拉应变区域的面积

    Table  4.   Location of neutral axis and area of compressive and tension strain region for beam with a hole located at compression zone under different loads

    载荷阶段
    Load stage
    载荷值
    Load/kN
    y0/mm Ac/AI At/AI Ac/At
    25%Fmax 0.60 10.03 0.49 0.51 0.99
    50%Fmax 1.19 7.85 0.60 0.40 1.55
    75%Fmax 1.79 6.55 0.67 0.33 2.05
    Fmax 2.38 5.91 0.70 0.30 2.38
    下载: 导出CSV

    表  5  不同载荷时孔洞位于受拉区的木梁的中性轴位置与压应变区域和拉应变区域的面积

    Table  5.   Location of neutral axis and area of compressive and tension strain region for beam with a hole located in tension zone under different loads

    载荷阶段
    Load stage
    载荷值
    Load/kN
    y0/mm Ac/AI At/AI Ac/At
    25%Fmax 0.73 10.58 0.47 0.53 0.89
    50%Fmax 1.47 10.25 0.48 0.52 0.95
    75%Fmax 2.20 9.77 0.51 0.49 1.05
    Fmax 2.93 9.37 0.53 0.47 1.13
    下载: 导出CSV
  • [1] 廖春晖, 张厚江, 黎冬青, 等.古建筑圆柱形木构件内部缺陷筛查方法研究[J].北京林业大学学报, 2013, 35 (1): 123-126. http://j.bjfu.edu.cn/article/id/9864

    LIAO C H, ZHANG H J, LI D Q, et al. Screening method of internal defects in cylindrical wood members of ancient architectures[J].Journal of Beijing Forestry University, 2013, 35 (1): 123-126. http://j.bjfu.edu.cn/article/id/9864
    [2] 徐华东, 王立海.局部缺陷对木梁动弹性模量的影响[J].建筑材料学报, 2011, 14 (5): 653-658. doi: 10.3969/j.issn.1007-9629.2011.05.015

    XU H D, WANG L H. Effect of local defects on dynamic modulus of elasticity of wood beams[J]. Journal of Building Materials, 2011, 14 (5): 653-658. doi: 10.3969/j.issn.1007-9629.2011.05.015
    [3] 崔英颖, 张厚江.木材节子个数与其振动模态参数关系的研究[J].木材加工机械, 2006, 17(5): 5-9. doi: 10.3969/j.issn.1001-036X.2006.05.002

    CUI Y Y, ZHANG H J. Study on the relationship of number of wood knots and parameters of wood vibrational mode[J]. Wood Processing Machinery, 2006, 17 (5): 5-9. doi: 10.3969/j.issn.1001-036X.2006.05.002
    [4] KOLLMANN F F P, COTE W A, Jr. Principles of wood science and technology I: solid wood[M]. Berlin: Springer-Verlag, 1968.
    [5] BUKSNOWITZ C, HACKSPIEL C, HOFSTETTER K, et al. Knots in trees: strain distribution in a naturally optimised structure[J]. Wood Science and Technology, 2010, 44 (3): 389-398. doi: 10.1007/s00226-010-0352-4
    [6] 陈国, 张齐生, 黄东升, 等.腹板开洞竹木工字梁受力性能的试验研究[J].湖南大学学报(自然科学版), 2015, 42(11): 111-118. doi: 10.3969/j.issn.1674-2974.2015.11.016

    CHEN G, ZHANG Q S, HUANG D S, et al. Experimental study on mechanical performance of OSB webbed bamboo I shaped joist with web openings[J]. Journal of Hunan University (Natural Sciences), 2015, 42(11): 111-118. doi: 10.3969/j.issn.1674-2974.2015.11.016
    [7] ARDALANY A, FRAGIACOMO M, DEAM B, et al. Analytical cracking load estimation of laminated veneer lumber (LVL) beams with holes[J]. European Journal of Wood and Wood Products, 2013, 71 (1): 37-48. doi: 10.1007/s00107-012-0646-3
    [8] BETTS S C, MILLER T H, GUPTA R. Location of the neutral axis in wood beams: a preliminary study[J]. Wood Material Science and Engineering, 2010, 5(3/4): 173-180.
    [9] DAVIS P M, GUPTA R, SINHA A. Revisiting the neutral axis in wood beams[J]. Holzforschung, 2012, 66 (4): 497-503. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=10.1515/hf.2011.180
    [10] VOIGT L R. Location of the neutral axis in wood beams with multiple knots[D]. Corvallis: Oregon State University, 2011.
    [11] MILLER T H. Location of the neutral axis in wood beams[D]. Corvallis: Oregon State University, 2007.
    [12] ZHANG Z X, SHEN Q, GOU X F. Influence of the movement of the neutral axis on the relation between the critical current and strain in bending Bi2223/Ag composite tapes[J]. Journal of Superconductivity and Novel Magnetism, 2015, 28 (12): 3535-3543. doi: 10.1007/s10948-015-3226-z
    [13] BAŽANT Z, JIRÁSEK M. Inelastic analysis of structures[M]. West Sussex: John Wiley & Sons, Ltd., 2002: 351-353.
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出版历程
  • 收稿日期:  2017-06-20
  • 修回日期:  2017-10-06
  • 刊出日期:  2017-11-01

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