A numerical study on the friction and wear predictions of finger lock chuck in landing gear

Abstract

Locking mechanism is an important part of landing gear, which is required to lock retractable landing gear during taking off and landing processes of aircraft. This paper introduces an effective numerical simulation forecasting method to investigate the friction and wear of unworn finger lock chuck, where an associated experiment was conducted to verify the correctness of the method. The dynamic explicit procedure was adopted in the simulation process with Abaqus/Explicit solver, the user subroutine VFRIC integrated in the commercial package ABAQUS was coded to study the rate-dependent dynamic friction coefficient during the movement of unworn finger lock chuck. The friction simulation results indicate that large deformation occurs in the finger lock chuck during the unlocking–locking process and the maximum stress lies in the root zone of finger lock chuck, the difference of axial acting force between simulation results and experiment results of unworn finger lock is small. From the perspective of frictional energy dissipation, nodal frictional energy density rate within contact footprint regions was taken as the index to assess the wear severity. Python language commands were programmed to realize the secondary development of ABAQUS post-process, the nodal frictional energy density rate distribution in contact footprint regions of finger lock chuck was graphically displayed. The wear simulation results show that the nodal frictional energy density rate distribution of finger lock chuck concentrates significantly at the regions of two rounded corners in the raised portion of chuck and inner side surface of the raised platform, indicating that wear first occurs in these regions after the unworn finger lock chuck is put into use. The wear simulation results obtained was compared with a worn finger lock chuck after 500 times disengagement-stuck processing wear test, and the results are basically accordant.