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Fundamental Study on Mehcanism of Deformation for Bonded Wood Materials

粘合木质材料变形机理的基础研究

基本信息

批准号：
08456084
负责人：
MIZUMACHI Hiroshi
金额：
$ 5.06万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

The three strain energy release rates, G_<IC>, G_<IIC>, and G_<IIIC>, of the adhesive joints corresponding to different deformation modes, namely, mode I,mode II and mode III,respectively, are their ability to resist crack propagation of solids in the adhesive layr. In this study, dependence of G_<IC>, G_<IIC> and G_<IIIC> on crack length were examined using the double-cantilever beam specimens by a compliance method, and the experimental conditions accorging to which G_<IC>, G_<IIC> and G_<IIIC> can be evaluated inrespective of the dimension of the specimen. The adhesive tensile strength and adhesive shear strength of the joints, where the same adhesives are used, were also measured. It was found that there is a positive correlation between the adhesive strength and square root of the strain eneygy release rete of the corresponding mode of deformation. However, thecorrelation coefficient was not necessarily high because a variety of commercially available adhesives were used in the first experiment. Then, in the next step of this study, some of the typical and well-defined adhesives were chosen, and again the strain energy release rates of the three different modes for the bonded wood specimens were evaluated, and at the same time the adhesive tensile strength and adhesive shear strength were measured. It was found that the rate-temperature superposition procedure can be applied to the strain energy release rates of the adhesive joints if they are measured as a function of both temperature and rates of deformation. Inaddition, there is a positive correlation between the adhesive shear strength and square root of the strain energy release rate of mode II in most cases, but the correlation between the adhesive tensile strength and square root of the strain energy release rate of mode I is expressed by a loop if the adhesive poiymer changes from the glassy state to the rubbery state within the temperature range of the experiments.

不同变形模式（即模式I、模式II和模式III）对应的粘接接头的三种应变能释放率G_<IC>、G_<IIC>和G_<IIIC>分别是其抵抗粘接层中固体裂纹扩展的能力。本研究利用双悬臂梁试件，通过柔度法检验了 G_<IC>、G_<IIC> 和 G_<IIIC> 对裂纹长度的依赖性，并根据实验条件，可以在不考虑试件尺寸的情况下评估 G_<IC>、G_<IIC> 和 G_<IIIC> 的裂纹长度。还测量了使用相同粘合剂的接头的粘合拉伸强度和粘合剪切强度。结果发现，粘合强度与相应变形模式的应变能量释放网的平方根之间存在正相关关系。然而，相关系数不一定高，因为第一个实验中使用了多种市售粘合剂。然后，在本研究的下一步中，选择了一些典型且明确的粘合剂，再次评估了粘合木材试件的三种不同模式的应变能释放率，同时测量了粘合拉伸强度和粘合剪切强度。研究发现，如果将粘合接头的应变能释放速率作为温度和变形速率的函数进行测量，则速率-温度叠加程序可以应用于粘合接头的应变能释放速率。此外，在大多数情况下，粘合剪切强度与模式II的应变能释放率的平方根之间存在正相关关系，但如果粘合剂聚合物在实验温度范围内从玻璃态转变为橡胶态，则粘合拉伸强度与模式I的应变能释放率的平方根之间的相关性用环表示。