Fracture mechanics approach on evaluation of residual strength of structural timbers having a crack which emanates in moisture non-steady state condition
潮湿非稳态条件下裂纹结构木材残余强度评价的断裂力学方法
基本信息
- 批准号:10660160
- 负责人:
- 金额:$ 1.98万
- 依托单位:
- 依托单位国家:日本
- 项目类别:Grant-in-Aid for Scientific Research (C)
- 财政年份:1998
- 资助国家:日本
- 起止时间:1998 至 1999
- 项目状态:已结题
- 来源:
- 关键词:
项目摘要
1. Creep and fracture of wood having a crack under humidity steady stateCompact tension specimens designed by an ASTM standard were subjected to tensile stress perpendicular to a crack surface. Sugi and hemlock were used. Creep tests were done under stress levels from 45 % to 85% of maximum load. Crack opening displacement, acoustic emission(AE), clack length, humidity and temperature were measured simultaneously during tests. A life time of a specimen during a creep failure can be estimated by a minimum creep speed of COD during a steady creep stage. Above stress level of 60%, AE was detected frequently at initial creep stage and before catastrophic fracture. A few AE was also detected during steady creep stage. A creep limit was estimated to be below a stress level of 50%, because no AE was detected at this stress level.2. Creep and fracture of wood having a crack under humidity non-steady stateCreep tests of sugi under natural environmental condition were conducted. Fracture occurred relatively low stress level, below 40%. Crack propagation occurred when high humidity condition continued in such as a rainy day. COD creep curves showed daily cyclic change, however, a mechano-sorptive phenomenon which commonly occurres at a clear wood specimen was not observed. Inner stress induced by moisture absorption increased a stress intensity factor near a crack tip, and it accelerated a crack propagation.3. Effect of loading speed and modelization by a stress relaxation testEffect of loading speed on fracture of wood having a crack was tested. Speed effect on load-COD diagram was explained by stress relaxation tests and a modelization using a Maxwell model. A fracture criterion based on elastic component of AE was proposed to characterize a critical condition.
1.含裂纹木材在湿度稳定状态下的蠕变与断裂按ASTM标准设计的紧凑拉伸试样在垂直于裂纹面的方向上受到拉应力作用。使用了杉和铁杉。蠕变试验是在最大载荷的45%至85%的应力水平下进行的。在试验过程中同时测量裂纹张开位移、声发射、瓣长、湿度和温度。蠕变破坏时试样的寿命可以通过稳态蠕变阶段COD的最小蠕变速度来估算。在60%以上的应力水平下,在蠕变初始阶段和灾难性断裂之前经常检测到AE。在稳态蠕变阶段也检测到少量AE。蠕变极限估计为低于50%的应力水平,因为在该应力水平下未检测到AE。含裂纹木材在湿度非稳态下的蠕变与断裂对杉木在自然环境条件下进行了蠕变试验。断裂发生的应力水平相对较低,低于40%。裂纹扩展发生在高湿度条件下,如下雨天。COD蠕变曲线呈日循环变化,但未观察到木材中常见的机械吸附现象。吸湿引起的内应力增大了裂纹尖端附近的应力强度因子,加速了裂纹的扩展.加载速度的影响及应力松弛试验模型化研究了加载速度对含裂纹木材断裂的影响。通过应力松弛试验和麦克斯韦模型解释了速度对负荷COD图的影响。提出了一种基于声发射弹性分量的断裂准则来表征临界条件。
项目成果
期刊论文数量(3)
专著数量(0)
科研奖励数量(0)
会议论文数量(0)
专利数量(0)
Maki, OGAWAi and Nobuo, SOBUE: "Effect of loading speed of fracture of timbers with a crack"Mokuzai Gakkaishi. 45(6). 461-470 (1999)
Maki, OGAWAi 和 Nobuo, SOBUE:“带裂纹木材断裂的加载速度的影响”Mokuzai Gakkaishi。
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- 影响因子:0
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- 通讯作者:
小川真貴,祖父江信夫: "き裂を有する木材の破壊に及ぼす負荷速度の影響"木材学会誌. 45(6). 461-470 (1999)
Maki Okawa,Nobuo Sobue:“加载速度对裂纹木材断裂的影响”,日本木材科学学会杂志 45(6) 461-470 (1999)。
- DOI:
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- 影响因子:0
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小川真貴、祖父江信夫: "き裂を有する木材の破壊に及ぼす負荷速度の影響"木材学会誌. 45(6). 461-470 (1999)
Maki Okawa,Nobuo Sobue:“加载率对裂纹木材断裂的影响”,日本木材科学学会杂志 45(6) 461-470 (1999)。
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SOBUE Nobuo其他文献
Proceedings of the International Conference on Electromagnetic Wave Interaction with Water and Moist Substance (ISEMA) 2009
2009 年电磁波与水和潮湿物质相互作用国际会议 (ISEMA) 论文集
- DOI:
- 发表时间:
2009 - 期刊:
- 影响因子:0
- 作者:
吉永秀一郎;阪田匡司;酒井武;森貞 和仁;Morisada K.;吉永 秀一郎;吉永秀一郎;森貞和仁;吉永秀一郎;SOBUE Nobuo - 通讯作者:
SOBUE Nobuo
Monitoring of individual moisture content of piled timbers during drying by impedance tomography method
阻抗断层扫描法监测干燥过程中堆放木材的个体含水量
- DOI:
- 发表时间:
2009 - 期刊:
- 影响因子:0
- 作者:
吉永秀一郎;阪田匡司;酒井武;森貞 和仁;Morisada K.;吉永 秀一郎;吉永秀一郎;森貞和仁;吉永秀一郎;SOBUE Nobuo;Nobuo Sobue - 通讯作者:
Nobuo Sobue
SOBUE Nobuo的其他文献
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{{ truncateString('SOBUE Nobuo', 18)}}的其他基金
Development of high frequency CT monitoring of moisture contents of individual timbers piled in kiln
窑内堆放木材含水率高频CT监测技术的发展
- 批准号:
19580185 - 财政年份:2007
- 资助金额:
$ 1.98万 - 项目类别:
Grant-in-Aid for Scientific Research (C)
Fracture mechanics analysis of the crack development in structural timbers under high temperature drying
高温干燥结构木材裂纹扩展的断裂力学分析
- 批准号:
14560132 - 财政年份:2002
- 资助金额:
$ 1.98万 - 项目类别:
Grant-in-Aid for Scientific Research (C)
Identification of defects of wood by using wave analysis of tap tone and application to machine stress rating of lumber
利用敲击声波分析识别木材缺陷及其在木材机械应力评级中的应用
- 批准号:
12660148 - 财政年份:2000
- 资助金额:
$ 1.98万 - 项目类别:
Grant-in-Aid for Scientific Research (C)
REUSE OF RUBBER WASTE OF AUTOMOBILES AS WOOD-RUBBER COMPOSITE MATERIALS FROM THE VIEWPOINT OF LOCAL RECYCLE OF INDUSTRY WASTE.
从工业废物本地化回收的角度看汽车橡胶废料作为木橡胶复合材料的再利用。
- 批准号:
08660201 - 财政年份:1996
- 资助金额:
$ 1.98万 - 项目类别:
Grant-in-Aid for Scientific Research (C)
DEVELOPMENT OF THE FUNCTIONS FOR AUTOMATED DENSITY CORRECTION AND MOISTURE GRADIENT MEASUREMENT OF HIGH FREQUENCY MOISTURE METER
高频水分计自动密度校正和水分梯度测量功能的开发
- 批准号:
07556040 - 财政年份:1995
- 资助金额:
$ 1.98万 - 项目类别:
Grant-in-Aid for Scientific Research (B)
Improvement of electrical properties of wood by combination with ceramics
与陶瓷结合改善木材的电性能
- 批准号:
04660182 - 财政年份:1992
- 资助金额:
$ 1.98万 - 项目类别:
Grant-in-Aid for General Scientific Research (C)
Development of Dynamic Portable Graders for Structural Lumber Using Tapping Method
攻丝法动态便携式结构材平地机的研制
- 批准号:
01860021 - 财政年份:1989
- 资助金额:
$ 1.98万 - 项目类别:
Grant-in-Aid for Developmental Scientific Research (B).
Fundamental Research on the Development of the Fracture Analysis of Wood Using the Piezoelectric Effect.
利用压电效应进行木材断裂分析的基础研究。
- 批准号:
01560182 - 财政年份:1989
- 资助金额:
$ 1.98万 - 项目类别:
Grant-in-Aid for General Scientific Research (C)
Analysis of fracture mechanism of bolted joints and nail joints in LVL
LVL中螺栓接头和钉接头断裂机理分析
- 批准号:
62560174 - 财政年份:1987
- 资助金额:
$ 1.98万 - 项目类别:
Grant-in-Aid for General Scientific Research (C)
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