碳纤维复合材料改善焊接接头疲劳性能的基础研究

项目名称： 碳纤维复合材料改善焊接接头疲劳性能的基础研究

项目编号： No.50808139

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 陈涛

作者单位： 同济大学

项目金额： 21万元

中文摘要： 纤维复合材料改善钢结构性能的研究已成为当前土木工程中的重要课题之一，但对焊接接头的疲劳性能的研究尚处于探索阶段。本项目首先对非承重十字形和纵向焊接接头进行疲劳试验，结果表明复合材料用量和焊趾半径对疲劳寿命有关键影响。随后采用不同损伤程度的钢板试件以剔除焊趾半径的影响，通过疲劳试验考察疲劳裂纹的扩展和纤维材料的用量、初始损伤程度等相互关系。基于经典断裂力学方法，对复合材料补强试件进行理论分析，探索疲劳寿命预测模型。同时基于有限元数值方法，对焊趾处的应力强度因子进行分析，探求加固前后试件疲劳失效机理。为深入研究疲劳裂纹的扩展过程，采用边界元数值方法对裂纹的扩展寿命进行计算，进而得到应力幅-疲劳寿命曲线，揭示单双面补强方法、材料用量、模量以及胶层厚度等参数对疲劳寿命的影响。为纤维复合材料在钢结构修缮维护中的应用提供基础。

中文关键词： 纤维复合材料；焊接接头；疲劳寿命；有限元；边界元

英文摘要： The improvement of fatigue performance with fibre reinforced materials strengthening has been developed as a promising research topic at the moment. However, study on the fatigue behavior of welded joints is still in the exploratory stage. Non-load-carrying cruciform and longitudinal welded joints have been tested with fatigue machine. The experimental results indicate that the amount of fibre materials and weld toe radius are influential parameters to the fatigue life. Thereafter, center cracked plates with various initial crack lengths were tested to exclude the effects of the scatter of weld toe radius. Beach marking was observed with regard to the amount of fibre reinforced materials and initial crack lengths. Theoretical analysis was conducted to study the fatigue life model of strengthened specimens based on classical fracture mechanics. Stress intensity factors were calculated through finite element method. Failure mechanism was explored. Boundary element method was also adopted to investigate the crack propagation life. Then stress ranges versus number of fatigue cycles were obtained. Effects of double or single sided patch methods, fibre material layers, Young's modulus and adhesive thickness on fatigue life were discussed. This study will promote the implementation of new materials and technology in the strengthening of steel structures.

英文关键词： Fiber reinforced polymer; welded joint; fatigue life; FEM; BEM