| This article carried out the following research based on the MSD crack propagation of fuselage skin plate lap structure.Referencing the skin lap structure of Boeing 737 aircraft, simplified model is established by ANSYS, and using the crack propagation modeling software FRANC3 D to calculate stress intensity factor. Through changing the initial crack condition to calculate the stress intensity factor of three kinks of crack mode,which are included crack of hole edge, crack to crack and connecting crack. And analysis the influence of three conditions on the stress intensity factor at the crack tip.Based on the combination method to calculate stress intensity factor on the crack tip, this article analyze the probability of occurring WFD on collinear porous wall through combining the probability method of simulating crack initiation and deterministic method of crack propagation.Writing the calculation program of crack propagation based on the database of stress intensity factor to simulate the crack propagation of MSD. The result is to get the crack propagation life under different initial crack condition.This article reference actual aircraft longitudinal skin lap structure to design test article,improve the test fixture, and complete the WFD test of fuselage skin lap structure. We get some dates including the life of crack initiation, the length of initial crack, the position of crack initiation and the length of crack. And summarize the rule of MSD crack propagation in the test's process. At last, I analyze the reliability of fatigue life based on the test date. |
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