Analysis of the fatigue life of riveted sheet metal helicopter airframe joints

This paper provides a brief review of a literature search on fatigue life of riveted airframe sheet metal joints and then a description of a test and analysis program conducted for common riveted joints used in rotorcraft airframe structures. Many papers dealing with fatigue test and analysis of fastened sheet metal have been published. These papers reveal a wide range of factors that may affect the fatigue life of such structures, and this paper provides a summary of this published literature. The test and analysis program was conducted on 4.8 mm diameter rivets which are common in rotorcraft airframe structure. The test specimens were manufactured, completed, and assembled in a production environment using production personnel, materials, and facilities. Various common fastener types, joint geometries, and materials were included in the testing. Static tests and threedimensional finite element analysis were performed to evaluate fastener load distributions and local stress fields. Fatigue tests were conducted to obtain data for evaluating the effects of fastener type, joint geometry, and joint material. Limited fatigue tests were also conducted on ‘damaged’ and painted specimens.