高锁螺栓孔进R区的对接结构疲劳试验研究

Investigation of Fatigue Test of Joint Structure for Hi-lock Bolt Interferes with Bend Radius

在民用飞机生产过程中,存在紧固件孔进入对接结构R区但换新超差结构较为困难的情形,对该类问题在R区加弧形垫后,由于应力集中系数的变化及非标准连接,结构的疲劳品质会受到影响。本文通过疲劳试验研究对接结构高锁螺栓孔进R区(平行载荷方向)加弧形垫对结构细节疲劳额定值的影响;在试验件设计时通过有限元法分析部分参数对结构应力集中的影响,根据有限元分析结论进行三组疲劳试验以得到相应的细节疲劳额定值修正系数,对试验结果与工程算法结果进行比较。结果表明:高锁螺栓孔进R区的超差程度优于高锁螺栓HST12AG6的孔进R区1.0 mm,对接结构细节疲劳额定值下降在10%以内;试验对照组的试验件破坏形式与参照组完全吻合,细节疲劳额定值差异在合理的范围内。

In the process of civil aircraft production,it is difficult to avoid the situation that the fastener is punched into the bend radius of joint structure,and it is hard to replace the out-of-tolerance parts because of some limits of objective condition.When filler is utilized to fit the bend radius to deal with this issue,the fatigue quality of joint structure will be affected due to the change of stress concentration and the non-standard installation of fastener.In this paper,the influence on the detail fatigue rating(DFR)values of the repaired structure is investigated by fatigue tests.During the design of test specimen,the influence of some parameters on stress concentration factor is ana⁃lyzed by finite element method.According to the results of finite element analysis,three groups of fatigue tests are carried out to get the corresponding correction coefficient of DFR values.The fatigue test results are compared with the results of engineering calculation method.The results show that,in the case of the out-of-tolerance degree of hi-lock bolt withbend radius is better than that of the hole of HST12AG6 is punched into the bend radius 1.0 mm,the detail fatigue rating values of the joints are decreased within 10%.The failure mode of the fatigue test group which fasteners are installed standardly is completely consistent with the reference group,and the difference of de⁃tail fatigue rating values is within the reasonable range.