Development of the evaluation method on the strength of I type structure with an interface crack

I型结构材料作为一种轻质结构，应用广泛.当使用I型结构时，由于应力集中，在接合部分处经常出现界面裂纹。即使I型结构材料具有一定量的界面裂纹，从成本考虑，也希望其能够连续且安全地使用。因此，有必要建立I型结构中界面裂纹尺寸的允许标准。也就是说，作为I型结构的剩余寿命问题，需要对具有界面裂纹的I型结构的强度进行评估。本文对蜂窝板粘贴在芯体上的I型结构的芯体单元壁缺陷引起的应力集中问题进行了分析和研究。拉应力集中和弯矩集中被认为是由于缺陷而在缺陷附近的细胞壁中的应力集中。本文首先研究了在没有粘贴板的情况下，即只粘贴板的情况下的拉应力集中和弯矩集中，并提出了预测应力集中的工程技术。其次，研究了板粘贴在芯体上时的拉应力集中和弯矩集中问题。特别是对板芯之间的力分配进行了理论分析。根据试验所获得的知识，从单独堆芯的情况出发，提出了预测I型结构应力集中的工程技术。

As lightweight structure, I type structure material is used widely. It is frequent that an interface crack arises at a junction part due to stress concentration, while using I type structure. Even if I type structure material has a certain amount of interface crack, it is desirable that it can be used continuously and safely from a consideration of cost. For this reason, it is necessary to establish the standard of the permission about the size of an interface crack existing in an I type structure. That is, evaluation method on the strength of I type structure with an interface crack is needed as a problem of the remaining life of the I type structure. In this research, analysis and examination were performed about the stress concentration by the defect of the cell wall in a core for the I type structure, in which a plate pastes up on a core like a honeycomb. The tension stress concentration and the moment concentration are considered as the stress concentration in the cell wall near a defect due to a deficit. In this research, firstly, the tension stress concentration and the moment concentration are studied for the case where the plate was not pasted on the core, namely the case of a core alone, and the engineering technique was proposed for predict of the stress concentration. Secondly, the tension stress concentration and the moment concentration are studied for the case where the plate was pasted on the core. Especially, theoretical examination was performed about force distribution between the plate and the core. Based on the knowledge acquired from the examination, the engineering technique for predict of the stress concentration in I type structure is proposed from the technique for the case of the core alone.