Structure design and breakaway failure analysis of fuse-pin for civil main landing gear

Abstract

The landing gear should be able to achieve safe and rapid separation from the aircraft body under overload conditions. To clarify the effect of breakaway groove on the breakaway load of emergency fuse-pin for civil main landing gear, a series of FEM simulations are conducted to study the influence of structural changes of breakaway groove on the breakaway load for outer-groove, long outer-groove, inner-groove and short inner-groove emergency fuse-pin. The breakaway load and failure mode are comparatively analyzed between inner-groove and outer-groove emergency fuse-pin by experimental tests. The results show that the breakaway failure of fuse-pin is extended from inside to outside. The breakaway loads increase with the increasing of the sectional area and exhibit a linear relationship. The breakaway load variation with the sectional area（shear strength coefficient）of through-hole pin is the maximum, followed by outer-groove pin, and the inner-groove pin is the minimum. Compared with other pins, the breakaway load of inner-groove pin is easy to control and less affected by sectional area and overall size. The fracture morphology is changed from ductile fracture of outer-groove pin to brittle fracture of inner-groove pin. Accordingly, the design of inner-groove pin meets the aviation regulations requirement for civil main landing gear.

Keywords

• main landing gear
• emergency fuse-pin
• breakaway load
• fracture morphology
• failure mode