冷挤压孔的有限元分析研究(英文)

带切缝衬套的冷挤压强化技术由于引入了残余应力，可以显著提高飞机紧固件孔的疲劳寿命。本文针对目前的研究冷挤压孔边残余应力，大都采用基于厚壁圆筒的轴对称小变形、平面应力状态、孔边受力为均布载荷等假设所带来的不足，提出了采用三维分析模型，并考虑衬套对孔边受力的影响、试件在孔轴线方向上的应力差异等因素，研究了带衬套挤压件在加载、卸载及疲劳拉伸载荷状态下的应力分布，并与无衬套挤压时的状态进行比较，从机理上揭示了带衬套挤压在改善试件抗疲劳性能方面的优势。

RESEARCH ON COLD EXPANDED HOLE WITH FEM

Because of the generated residual stress after applying cold expanded technique with split sleeve, fatigue life of joint hole in aircraft can be distinguishedly prolonged. To study residual stress around cold expanded hole, some hypothesises such as small deformation in radial symmetry, plane stress, plane strain, uniform distribution pressure have been presented in most papers. However, accurate result cannot be gained based on these hypothesises. In order to overcome the shortage, a 3 dimensional model is proposed which takes into consideration of the effect on split sleeve and the different distribution pressure along thick direction of specimen. The stress distributions of cold expanded hole with split sleeve under loading or unloading, as well as under fatigue tension have been stu died. To reveal the advantage of cold expanding process with split sleeve, the expansion without split sleeve has also been studied and compared with the former.