Aerospace Science and Technology
alireza moradi; fathollah ommi; Zoheir Saboohi
Abstract
In the course of all-round advancement of engineering science, space research can be considered as the drivers of this forward movement. In the field of space propulsion, this trend can be seen as a backward trend, not in the sense of regression, but in the sense of optimizing the original designs used ...
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In the course of all-round advancement of engineering science, space research can be considered as the drivers of this forward movement. In the field of space propulsion, this trend can be seen as a backward trend, not in the sense of regression, but in the sense of optimizing the original designs used for space systems, which not only lead to the re-invention of these systems based on the acquisition of specific modern manufacturing technologies, but also strengthened the link between sciences such as Materials science and Mechanics science. In this research, according to the space propulsion system roadmap and also the review of old and reference designs, an attempt has been made to study some of the optimizations made in recent years and to express the weaknesses and challenges ahead. One of the ideas that optimizes, minimizes and increases the reliability of the space propulsion system is the injection of fuel through the porous media. The study of a type of showerhead injector expresses the formation path of the idea of using porous materials in the injection system and then the efficiency of these two types of injections is compared in a design that connects the porous material with the coaxial injector design.
Aerospace Science and Technology
Enayatollah Hosseinian; Ali Nouri; Majid Zia
Volume 12, Issue 1 , March 2019, , Pages 53-63
Abstract
In this paper, nonlinear vibration analysis of functionally graded piezoelectric (FGP) beam with porosities material is investigated based on the Timoshenko beam theory. Material properties of FG porous beam are described according to the rule of mixture which modified to approximate material properties ...
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In this paper, nonlinear vibration analysis of functionally graded piezoelectric (FGP) beam with porosities material is investigated based on the Timoshenko beam theory. Material properties of FG porous beam are described according to the rule of mixture which modified to approximate material properties with porosity phases. The Ritz method is used to obtain the governing equation which is then solved by a direct iterative method to determine the nonlinear vibration frequencies of FGP porous beam subjected to different boundary conditions. The effects of external electric voltage, material distribution profile, porosity volume fraction, slenderness ratios and boundary conditions on the nonlinear vibration characteristics of the FGP porous beam are discussed in detail. The results indicate that piezoelectric layers have significant effect on the nonlinear frequencies. Also it is found that the porosity has a considerable influence on the nonlinear frequency and these effects increased especially when the electric voltage is applied.
