Nolinear Post-buckling Properties Of Typical Thin-wall Structure

The surface of aircraft is usually consist of thin-walled structures and stiffened plate structure.During the high-speed flying period of aircraft,the outer surface will suffer strong aerodynamic and thermal loads,and become more vulnerable and easier to buckle.It is generally considered that structures will become unstable after loads exceed the critical buckling value,however,experiments show that the many buckled structures like beams and plates still have the ability to sustain higher loads and maintain balanced.Therefore,it is significant to delve into the characteristics of beams and plates during the post-buckling period and improve the sustain ability of structures,which is helpful to designing and reducing the weight of aircrafts.In this paper,the nonlinear Partial Differential Equations(PDEs)of lateral displacement of beam subjected to thermal load are derived based on the geometric nonlinearity.Each bifurcation of buckling mode and the critical load is derived through solving the eigenvalue equation,the buckling amplitude are also obtained with the help of analytical method.Based on the clamped boundary conditions,the stability characteristics are studied using the dynamic stability principle.The results show that the first buckling configuration is stable and the second and third buckling configurations are unstable.Based on Von-Karman large-deflection theory,the nonlinear PDEs respected to the lateral displacement of orthotropic plate subjected to both thermal and force load are derived.The first four critical loads of a specific material are obtained using ABAQUS software.Load-displacement curves of the node of the plate are drawn and used to obtain the critical ultimate load.Several factors,which may affect the ultimate load value,are discussed,such as initial imperfection and temperature.The results shows that initial imperfection and high temperature can both lower the critical buckling load.The ultimate buckling load under dynamic force such as half-wave sine pulse load,is found to be closely related to the duration time and load amplitude,and is also compared to the ones under static buckling load.