The Influence of Clearance on the Fatigue Life of the Connecting Lug Between the Landing Gear Shock Strut and the Down Lock Release Actuator

The single and double lug structure design of the landing gear buffer strut and down lock release actuator is that the single lug is located on the outer side of the double lug. Fatigue test results show that when there is a clearance between the lug and the connecting pins of double lug., cracks will appear at the edges of the lug., leading to fatigue failure. The analysis method through finite element simulation shows that due to the opposite direction of force on the two lug of double lug., the clearance will cause high stress areas at the edges of the lug., and the stress will increase with the increase of the clearance., resulting in a decrease in fatigue life. The relationship between clearance and life can be expressed by a cubic polynomial equation. Increasing the stiffness of the connecting pin and increasing the contact area with the lug can effectively reduce the stress level at the edge of the lug. Considering that the dimensional tolerance follows a normal distribution and the Three Sigma criterion., the Monte Carlo method is used to simulate the random process of tolerance generation., establish a probability model for lug failure calculation., and verify the effectiveness of the optimization scheme.