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

Abstract

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 analyzed 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 detail fatigue rating values is within the reasonable range.

Keywords

• joint structure
• hi-lock bolt
• finite element method
• fatigue test
• fatigue quality