Development Of Fatigue Life Prediction System For Typical Structural Components Containing Holes In Aircraft

According to statistics, in the course of the aircraft, more than 80% strength problems are caused by the fatigue damage. Detected in the aircraft fatigue cracks, the hole edge cracks up about one third. According to rough estimates, a large aircraft contains 1.5 million to 2 million rivets and bolts. Therefore, carrying out fatigue life study of typical components containing hole has important practical value. The process of components containing hole fatigue life prediction is complex and abstruse, and engineers need to spend so much time on it. The analysis's efficiency is low and the process of it needs large amounts of data which is not easily prone to errors found. Thus, this paper regards the components containing hole as the object of study, based on the method of parametric design theory, finite element method and fatigue life theory and so on, and chooses graphical user interface of MATLAB as a development platform, completing the calculation of the fatigue parameters with the ANSYS, performing calculation of complex fatigue life using MATLAB numerical calculation functions, and using ACCESS database to manage data. The system integrates the input of geometry parameters, loading parameters and material properties parameters and the output of the final results into one environment. The main research contents are as follows:First of all, regarding skins, stringers, frames and other typical aviation parts as the object of study, simplifying the forces and structure relying on stress severity factor method, making functional analysis of the system to determine the input and output and the need to complete the function of the system development, achieve the fatigue life accurately, quickly and easily predict.Secondly, regarding lug as the object of study, simplifying the forces and structure, predict the fatigue life by nominal stress, local stress-strain and fracture mechanics method. The system realizes the lug parametric modeling, finite element software is automatically invoked to obtain the stress, strain, stress intensity factor for fatigue life prediction; can achieve fatigue life prediction under constant amplitude, program and random loading, generates fatigue curves based on fatigue test data, automatic access to material fatigue performance parameters.Finally, solve a number of problems of MATLAB, ANSYS and ACCESS mixed programming. MATLAB GUI uses non-system controls. Solve the MATLAB and ACCESS, MATLAB and ANSYS data interface problems. In the design of APDL programming, solve the loading of arbitrary angle cosine loading, establish full crack geometry model under arbitrary crack length and angle and solve the stress intensity factor.