随机载荷作用下锥形螺栓干涉配合的疲劳寿命增益

 介绍了以7475 T761铝合金为基材的锥形螺栓干涉配合和普通螺栓非干涉配合连接的犬骨形试件,在随机疲劳载荷谱作用下的疲劳试验。结果表明:锥形螺栓干涉配合与普通螺栓连接比较,疲劳寿命增益明显;应力水平降低,寿命增益倍数增加。锥形螺栓干涉提高疲劳寿命的主要原因是:(1)干涉使孔附近区域形成拉伸预应力,它可以降低外加疲劳载荷引起的交变应力幅;(2)锥形螺栓干涉使螺栓与孔之间的接触更均匀、更紧密,当有载荷传递时,其分布趋于均匀;(3)锥形螺栓干涉改善了孔壁的初始疲劳质量。

FATIGUE LIFE INCREMENT OF INTERFERENCE FIT TAPERED SHANK BOLT CONNECTIONS UNDER RANDOM LOADING

Random load fatigue tests were performed on the 7475 T761 aluminium dog bone specimens. Some of the specimens were interference fit tapered shank bolt connections(IFBC), and the others were ordinary cylindrical shank bolt connections(OBC). It was shown that fatigue lives of the IFBC increased atuleast by twice as compared with those of OBC for the test stress levels, and the fatigue life increment would increase with the stress level reduction. The main reasons for the fatigue life increment of the IFBC are: (1) The tensile prestresses are introduced in material around the bolt holes, it may reduce the applied alternative stress amplitudes; (2) The pin load distribution on the walls of the bolt holes for the IFBC is more uniform; (3) The initial fatigue quality of the bolt holes is improved by the interference between the bolt and the bolt holes.