مهندسی دریا
Masih Moore; Ahmad Firouzian-nejad; Saeed Ziaei-Rad; Abdollah Eidany-nejad
Abstract
The interest in bi-stable structures comes from their ability that these structures can have two different stable equilibrium configurations to define a discrete set of stable shapes. The geometrical changes occur with no need to continuously consume power, and mechanical hinges to preserve the structure ...
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The interest in bi-stable structures comes from their ability that these structures can have two different stable equilibrium configurations to define a discrete set of stable shapes. The geometrical changes occur with no need to continuously consume power, and mechanical hinges to preserve the structure in each stable shape. In this study, the stability characteristics and thermal response of a bistable composite plate with different asymmetric composition were considered. The non-linear finite element method (FEM) was utilized to determine the response of the laminate. Attention was focused on the temperature dependency of laminate mechanical properties, especially on the thermal expansion coefficients of the composite graphite-epoxy plate. Also the effect of including the resin layers on the stability characteristics of the laminate was investigated. The effect of the temperature on the laminate cured configurations in the range of 25°C to 180°C was examined. The results indicate that the coefficient of thermal expansions has a major effect on the cured shapes. Next, optical microscopy was used to characterize the laminate composition and for the first time the effect of including the resin layers on the actuation loads that causes snapping behavior between two stable shapes was studied. The results obtained from the finite element simulations were compared with experimental results and a good correlation was obtained.
مهندسی دریا
M Moore; A. Firouzian nejad; S. ZiaeRad; A. Eidani nezhad
Abstract
The interest in bi-stable structures comes from their ability that these structures can have two different stable equilibrium configurations to define a discrete set of stable shapes. The geometrical changes occur with no need to continuously consume power, and mechanical hinges to preserve the structure ...
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The interest in bi-stable structures comes from their ability that these structures can have two different stable equilibrium configurations to define a discrete set of stable shapes. The geometrical changes occur with no need to continuously consume power, and mechanical hinges to preserve the structure in each stable shape.It is known that asymmetric composite laminates can have bi-stable response to different kind of loadings. In this research, the non-linear temperature-curvature relationship for the asymmetric composite laminates is studied using Rayleigh–Ritz technique. Attention is focused on studying the effect of material temperature dependency and resin layers; especially in the bifurcation point by use of analytical method. To this end, the well-known analytical theories are extended and used to consider the temperature dependency of material. The results obtained from the theory are then compared with the finite element simulations results and a good correlation is obtained. Finally, an experimental investigation is carried out and several specimens with [90/0]T, [70/–20]T and [70/20]T compositions were manufactured. In order to study the effect of resin layers, optical microscopy is utilized and the exact thickness of different layers in the manufactured specimens is determined. The thermal responses of the manufactured plates were measured and used to validate the results obtained from the analytical theory and finite element simulations
مهندسی دریا
Abdullah Eidani nezhad; A.Kabir Kabiri; S.H. Dibajian; A. Mardan
Abstract
There is an increasing interest in the marine industry to use composites to improve the hydrodynamic and structural performance of naval structures. The materials used within the composite are commercially available, and it is important the development of the right mix of fibers, resin and laminate lay-up ...
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There is an increasing interest in the marine industry to use composites to improve the hydrodynamic and structural performance of naval structures. The materials used within the composite are commercially available, and it is important the development of the right mix of fibers, resin and laminate lay-up that provide the desired mechanical and environmental performance for marine application. In this paper, to improve the stiffness and control the geometry of the blades of a marine propeller made of carbon/epoxy genetic algorithm to determination of optimal stacking Sequence is used. Using this method will minimize the deformation of tip blades. The optimization process has executed by linking ABAQUS and MATLAB software. Optimal angles of blade propeller obtained by using this process.