• Steel and Composite Structures
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• v.24 no.2
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• pp.249-264
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• 2017

In this paper free linear vibration of lattice composite conical shells will be investigated. Lattice composite conical shell consists of composite helical ribs and thin outer skin. A smeared method is employed to obtain the variable coefficients of stiffness of conical shell. The ribs are modeled as a beam and in addition to the axial loads, endure shear loads and bending moments. Therefore, theoretical formulations are based on first-order shear deformation theory of shell. For verification of the obtained results, comparison is made with those available in open literature. Also, using FEM software the 3D finite element model of composite lattice conical shell is built and analyzed. Comparing results of analytical and numerical analyses show a good agreement between them. Some special cases as variation of geometric parameters of lattice part, effect of the boundary conditions and influence of the circumferential wave numbers on the natural frequencies of the conical shell are studied. It is concluded, when mass and the geometrical ratio of the composite lattice conical shell do not change, increment the semi vertex angle of cone leads to increase the natural frequencies. Moreover for shell thicknesses greater than a specific value, the presence of the lattice structure has not significant effect on the natural frequencies. The obtained results have novelty and can be used for further and future researches.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.307-311
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• 2011

This paper is concerned with anisogrid composite lattice structures whose load bearing shell is formed by systems of geodesic unidirectional composite ribs made by automatic wet winding process. Lattice structures are usually made in the form of conical shell and consist of systems of helical and hoop ribs fabricated by continuous filament winding from carbon and epoxy composites. Design variables of the structure which are the angle of helical ribs and ribs spacings are determined by cone geometry and geodesic line. and Fabrication methods for the conical composite lattice structure are presented.

• Composites Research
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• v.33 no.3
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• pp.169-175
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• 2020

The compression and tension test were performed to evaluate the stiffnesses of the conical composite lattice structures and results of test were compared with finite element analysis results. Because of difficulty to perform simple tension and compression test due to conical shape, suitable specimens and jig for test were made. Subelements extracted from the structure were prepared for compression test. Compression test of subelement was performed and compressive strains in fiber direction were measured. Compressive stiffness of the helical rib was verified by finite element analysis results. For stiffness of hoop rib, hoop ring specimens were extracted from the structure. Tension test of hoop ring specimen was performed to apply bending deformation to hoop rib. Stiffness of hoop rib was verified by finite element model considering various fiber volume fraction in thickness direction.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.6
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• pp.74-86
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• 2021

The composite lattice structure is a structure that supports the required load with the minimum weight and thickness. Composite lattice structure is manufactured by the filament winding process using impregnating high-strength carbon fiber with an epoxy resin. Filament winding process can laminate and manufacture only structurally necessary parts, composite lattice structure can be applied to aircraft fuselages, satellite and launch vehicles, and guided weapons to maximize weight reduction. In this paper, the development and evaluation of the composite lattice structure corresponding to the entire process from design, analysis, fabrication, and evaluation of large-scale cylindrical and conical composites lattice structure were performed. To be applicable to actual projectiles and guided weapons, we developed a cylindrical lattice structure with a diameter of 2,600 mm and a length of 2,000 mm, and a conical lattice structure with an upper diameter of 1,300 mm, a lower diameter of 2,500 mm, and a length of 900 mm. The performance of the developed composite lattice structure was evaluated through a load test.