Space New Technologies
Sadjad Samipour; Alireza Toloei; Vladimir Batrakoff
Volume 15, Issue 4 , December 2022, , Pages 31-43
Abstract
Development in the aerospace industry is linked to the continuous pursuit of lightweight designs. Open-architecture composite structures are a new and novel use of composites for minimal-weight component design. It is reasonable to use efficient and advanced techniques such as radial braiding in the ...
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Development in the aerospace industry is linked to the continuous pursuit of lightweight designs. Open-architecture composite structures are a new and novel use of composites for minimal-weight component design. It is reasonable to use efficient and advanced techniques such as radial braiding in the manufacturing of composite lattice tubular structures. In this article, an aerospace composite lattice tubular structure with a braided reinforcement system is studied. A method is developed to determine the parameters of the preform reinforcement. A new process has been created for the manufacture of lattice structures with a braided reinforcement system. A methodology has been developed for determining the technological parameters of radial braiding. A sample structure is manufactured and tested. Experimental studies of lattice structure samples were carried out in order to verify the methods for determining mechanical, structural, and technological parameters.
Space New Technologies
Reza Kohandani; Ali Davar; Mohsen Heydari Beni; Jafar Eskandari Jam; Majid Eskandari Shahraki
Volume 15, Issue 1 , March 2022, , Pages 1-20
Abstract
In this research the free vibration analysis of simply supported grid stiffened doubly curved shells by using a refined higher order theory is presented. The advantage of the present theory in comparison with other higher order theories is investigation of the effects of trapezoidal shape factor in the ...
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In this research the free vibration analysis of simply supported grid stiffened doubly curved shells by using a refined higher order theory is presented. The advantage of the present theory in comparison with other higher order theories is investigation of the effects of trapezoidal shape factor in the stress resultants in order to obtain more accurate frequency results. The governing equations of motion and boundary conditions are obtained using Hamilton’s principle and solved by using the Galerkin method. In the case of grid stiffened shells, a distribution function is introduced for describing the physical discontinuity between the ribs and the bays. The results are validated by making comparison to those existed in the literature or those obtained using the present numerical simulation in ABAQUS/Standard solver. In most cases, validations illustrated excellent agreement between the results . Finally, the effects of geometrical properties, material property and layup on the frequency responses of the shell are discussed.
A. A. Jafari; A. Mozafari; M. Maghsoudi Mehrabani
Volume 4, Issue 1 , July 2011
Abstract
The effect of rotating speed and stiffeners on vibrations for composite rotors is investigated using Sander's shell theory. The frequency equation is derived implementing the Rayleigh-Ritz procedure based on energy method. The effects of initial hoop tension, centrifugal and Coriolis forces due to the ...
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The effect of rotating speed and stiffeners on vibrations for composite rotors is investigated using Sander's shell theory. The frequency equation is derived implementing the Rayleigh-Ritz procedure based on energy method. The effects of initial hoop tension, centrifugal and Coriolis forces due to the rotation are considered to derive governing equation. The displacement functions satisfying the both ends simply supported boundary conditions are assumed to be trigonometric expressions. By using simple shell theory like as Sander's shell theory the amount of equations and time expenditure are considerably reduced and provides feasible analysis, solution and design especially for composite materials optimization.UD composite materials are used for stiffeners. The effects of these stiffeners are evaluated by an averaging method. Some of stiffeners shapes are considered to optimize the ratio of natural frequency to weight.
