Load transfer in the stiffenertoskin joints of a pressurized fuselage
Abstract
Structural analyses are developed to determine the linear elastic and the geometrically nonlinear elastic response of an internally pressurized, orthogonally stiffened, composite material cylindrical shell. The configuration is a long circular cylindrical shell stiffened on the inside by a regular arrangement of identical stringers and identical rings. Periodicity permits the analysis of a unit cell model consisting of a portion of the shell wall centered over one stringerring joint. The stringerringshell joint is modeled in an idealized manner; the stiffeners are mathematically permitted to pass through one another without contact, but do interact indirectly through their mutual contact with the shell at the joint. Discrete beams models of the stiffeners include a stringer with a symmetrical cross section and a ring with either a symmetrical or an asymmetrical open section. Mathematical formulations presented for the linear response include the effect of transverse shear deformations and the effect of warping of the ring's cross section due to torsion. These effects are important when the ring has an asymmetrical cross section because the loss of symmetry in the problem results in torsion and outofplane bending of the ring, and a concomitant rotation of the joint at the stiffener intersection about the circumferential axis. Data from a composite material crown panel typical of a large transport fuselage structure are used for two numerical examples. Although the inclusion of geometric nonlinearity reduces the 'pillowing' of the shell, it is found that bending is localized to a narrow region near the stiffener. Including warping deformation of the ring into the analysis changes the sense of the joint rotation. Transverse shear deformation models result in increased joint flexibility.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 May 1995
 Bibcode:
 1995STIN...9527865J
 Keywords:

 Composite Structures;
 Cylindrical Shells;
 Elastic Deformation;
 Fourier Series;
 Fuselages;
 GraphiteEpoxy Composites;
 Joints (Junctions);
 Loads (Forces);
 Mathematical Models;
 Pressure Effects;
 Reinforced Shells;
 Stringers;
 Structural Analysis;
 Structural Design;
 Transport Aircraft;
 Bending Moments;
 Internal Pressure;
 Linear Equations;
 Load Distribution (Forces);
 Nonlinearity;
 Periodic Variations;
 Ring Structures;
 Shear Properties;
 Stress Concentration;
 Torsion;
 Warpage;
 Structural Mechanics