Fatigue Life Analysis of Balance Elbow Structure During Firing

As a key component of tracked armored vehicle, balance elbow connects vehicle body and road wheel. Balance elbow transmits large amount of impact energy generated by up and down movement of road wheel to torsion bar in order to reduce impact force on vehicle body. Performance of tracked armored vehicle is improved continuously, higher requirements are put forward for design of balance elbow. Fatigue life of balance elbow during firing while tracked armored vehicle is in parking state is calculated by simplified load spectrum method and rain-flow counting method. Difference between fatigue life results is only 3.81%. Simplified load spectrum method can meet certain accuracy requirements. Rain-flow counting method additionally considers other small stress cycles other than maximum stress cycle, which is more accurate for estimation of fatigue life of balance elbow. Considering uncertainty of load under other working conditions in battlefield, load on tracked armored vehicle during firing is increased by 20%-100%. Fatigue life of balance elbow is significantly reduced by 99.99% after load is increased by 100%.Balance elbow has plastic deformation with low-cycle fatigue characteristic. Influence of change of concave-circle`s diameter at root of mounting surface of balance elbow on its fatigue life is studied. Results show that when concave-circle`s diameter at root of mounting surface of balance elbow is 70mm, fatigue life of balance elbow is highest and 133% higher than design state, which provides an idea for optimization of fatigue life of balance elbow structure.