Study of the Effect of Cyclic Loads on the Joint in a Vertical Tail of Aircraft Structure

Joints are obvious critical locations in the aircraft structure because of the stress concentration. Joints are very common in every structural component of aircraft. Vertical tail (VT) is one of the major components of the airframe. Rudder attached to the VT is the control surface, which is used for controlling yawing motion of the aircraft. Side load on the VT causes it to bend on either side with respect to fuselage axis. Deflection of rudder introduces side load on the VT. This project includes the study of the effect of cyclic loads for crack initiation at the critical location of the VT. Stress analysis is the approach followed to identify the critical location. Finite element method will be used for stress analysis of the component. Loads representative of a small transport aircraft will be considered in this study. VT bending will cause tension and compressive stress field in the skin on either sides of VT. Joint details will be simulated through a local refined analysis to capture the gradient stress field near the concentration zone. Structure undergoes fatigue due to fluctuating side loads on VT. Fatigue damage is estimated using linear damage theory. S-N data curve of the aluminium alloy material used for the VT skin will be considered for stress based damage calculation.