Projects: Pressure
Vessels  FluidStructure  Buckling  Filament WInding
Buckling Strength of Composite Lattice Structures
Research by: An Hou
The buckling strength of composite lattice cylindrical and conical shells under
axial compressive loads is investigated. The lattice structures are composed of circumferential
and helical members, whose crosssections are rectangular. This research investigates
the buckling behavior of both cylindrical and conical composite lattice structures
and new design constraints for the most weight efficient structure with the highest
buckling load.
The main emphasis is placed on the effects of geometrical configuration of the
structure and the manufacturing process. It is observed that the effects of geometrical
configuration are the winding angle, the slenderness of a member and the inertial
properties of the members cross sections. The manufacturing process includes automated
winding, winding path control, bridging effects and the effect of tension force.
It is shown that these structures can be constructed by filament winding, the process
can be automated, and the manufacturing costs can be reduced.
Numerical results are obtained by finite element analysis which are compared with
experimental data and simplified analytical solutions. The motivation of the present
work is to find the optimal winding pattern which filament winding can be easily
applied and provides the highest strength to weight ratio. The problems caused during
the fabrication process are also discussed. The buckling shapes predicted by the
finite element analysis and the assumptions which were used in the theoretical and
finite element analysis were verified by experimental tests. The buckling behavior,
the geometric factors of structures and the fabrication process are fully investigated
and developed. The final result of this research includes the numerical and experimental
analysis of composite lattice cylindrical and conical shells via filamentwinding.
This provides a full understanding of composite lattice structures and can prove
to be helpful in preliminary design of such structures.
Thin, cylindrical shells have been used extensively as load bearing structures,
especially in the aerospace industry. Because of this, the stability of cylindrical
structures subjected to external loads is a critical structural problem for rocket
design, pressure vessels, rocket motor cases, gas tanks and aircraft pressure sources.
Elastic instability will cause buckling and eventually lead to catastrophic failure
of the structure. Thus it is important to show that the latticed structure fabricated
by filament winding has uniform properties and can be applied to actual structures.
Carbon/epoxy composite materials have been used in upper stage structures of satellite
launch vehicles in order to improve payload capability in Japan. The third stage
structures of the H1 and H2 launch vehicles are triangular lattice cylinders which
employ carbon fiber reinforced plastics (CFRP). One structure, called payload attach
fitting (PAF), is used for connecting the satellites and the third stage motors,
and the other, called motor attach fitting (MAF), is used for connecting the third
stage motors and the spintables of the launch vehicles.
Examples of finite element modeling of structure
The Triangle Lattice Cylinder under Uniform Compressive
Load.
The Hexagon Lattice Cylinder under Uniform Compressive Load.
Fabrication Process
It is proposed to fabricate the lattice by filament winding. Filament winding
is a technique used for manufacture of surfaces of revolution such as conical, cylindrical
and other three dimensional structures, and wound automatically by the numerically
controlled winding machine. The purpose of this trial is to show the lattice structure
can be economically constructed and the effect of filament winding on this type of
structure.
For additional details regarding the preceding work, contact An Hou at: gt8473a@prism.gatech.edu.
Projects: Pressure Vessels  FluidStructure  Buckling
 Filament WInding
© 1997 An Hou, Georgia
Institute of Technology, All Rights Reserved.
© 1997 Kurt Gramoll, The University
of Oklahoma, All Rights Reserved.
