气密载荷下机身长桁弯曲应力分析

摘要

On the basis of deducing the differential equation of fuselage structure under pressurization, by imposing speciifc boundary conditions, the analytical solution of local bending moment of fuselage structure under pressurization was derived. For a given example, by utilizing finite element analytical software MSC. NASTRAN, finite element models of a typical fuselage structure were built and analyzed. The comparison between the analytical solution and results of ifnite element analysis manifests that the conventional method of idealization by which the stringers are idealized as CROD elements can not reflect the bending effects produced by the local bending moment created by the discordance of deformation between the skin and frames. After a series of analysis, a reasonable method of idealization for the fuselage structure under pressurization was put forward.%针对机身结构，对气密载荷下机身长桁的弯曲应力进行了分析。在推导机身结构在承受气密载荷作用下的微分方程的基础上，通过施加特定边界条件，得到机身结构在承受气密载荷时局部弯矩的解析解，并应用MSC.Nastran大型有限元分析软件，建立有限元模型进行求解。分析结果表明：框与壁板由于变形不协调而产生了局部弯矩故对长桁产生了弯曲效应，即弯曲应力。