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RISS 인기검색어
- 검색키워드
- 저자 : Pourtakdoust, Seid H. (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
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Dynamic modeling and structural reliability of an aeroelastic launch vehicle
Pourtakdoust, Seid H.,Khodabaksh, A.H. Techno-Press 2022 Advances in aircraft and spacecraft science Vol.9 No.3
The time-varying structural reliability of an aeroelastic launch vehicle subjected to stochastic parameters is investigated. The launch vehicle structure is under the combined action of several stochastic loads that include aerodynamics, thrust as well as internal combustion pressure. The launch vehicle's main body structural flexibility is modeled via the normal mode shapes of a free-free Euler beam, where the aerodynamic loadings on the vehicle are due to force on each incremental section of the vehicle. The rigid and elastic coupled nonlinear equations of motion are derived following the Lagrangian approach that results in a complete aeroelastic simulation for the prediction of the instantaneous launch vehicle rigid-body motion as well as the body elastic deformations. Reliability analysis has been performed based on two distinct limit state functions, defined as the maximum launch vehicle tip elastic deformation and also the maximum allowable stress occurring along the launch vehicle total length. In this fashion, the time-dependent reliability problem can be converted into an equivalent time-invariant reliability problem. Subsequently, the first-order reliability method, as well as the Monte Carlo simulation schemes, are employed to determine and verify the aeroelastic launch vehicle dynamic failure probability for a given flight time.
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Dynamic modeling and structural reliability of an aeroelastic launch vehicle
Pourtakdoust, Seid H.,Khodabaksh, A.H. Techno-Press 2022 Advances in aircraft and spacecraft science Vol.9 No.3
The time-varying structural reliability of an aeroelastic launch vehicle subjected to stochastic parameters is investigated. The launch vehicle structure is under the combined action of several stochastic loads that include aerodynamics, thrust as well as internal combustion pressure. The launch vehicle's main body structural flexibility is modeled via the normal mode shapes of a free-free Euler beam, where the aerodynamic loadings on the vehicle are due to force on each incremental section of the vehicle. The rigid and elastic coupled nonlinear equations of motion are derived following the Lagrangian approach that results in a complete aeroelastic simulation for the prediction of the instantaneous launch vehicle rigid-body motion as well as the body elastic deformations. Reliability analysis has been performed based on two distinct limit state functions, defined as the maximum launch vehicle tip elastic deformation and also the maximum allowable stress occurring along the launch vehicle total length. In this fashion, the time-dependent reliability problem can be converted into an equivalent time-invariant reliability problem. Subsequently, the first-order reliability method, as well as the Monte Carlo simulation schemes, are employed to determine and verify the aeroelastic launch vehicle dynamic failure probability for a given flight time.
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Novel aspects of elastic flapping wing: Analytical solution for inertial forcing
Zare, Hadi,Pourtakdoust, Seid H.,Bighashdel, Ariyan Techno-Press 2018 Advances in aircraft and spacecraft science Vol.5 No.3
The structural dynamics (SD) behavior of Elastic Flapping Wings (EFWs) is investigated analytically as a novel approach in EFWs analysis. In this regard an analytical SD solution of EFW undergoing a prescribed rigid body motion is initially derived, where the governing equations are expressed in modal space. The inertial forces are also analytically computed utilizing the actuator induced acceleration effects on the wing structure, while due to importance of analytical solution the linearity assumption is also considered. The formulated initial-value problem is solved analytically to study the EFW structural responses, where the effect of structure-actuator frequency ratio, structure-flapping frequency ratio as well as the structure damping ratio on the EFW pick amplitude is analyzed. A case study is also simulated in which the wing is modeled as an elastic beam with shell elements undergoing a prescribed sinusoidal motion. The corresponding EFW transient and steady response in on-off servo behavior is investigated. This study provides a conceptual understanding for the overall EFW SD behavior in the presence of inertial forces plus the servo dynamics effects. In addition to the substantial analytical results, the study paves a new mathematical way to better understanding the complex role of SD in dynamic EFWs behavior. Specifically, similar mathematical formulations can be carried out to investigate the effect of aerodynamics and/or gravity.
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Ali Shahvarpour,Hossein Pourtakdoust,Gholam Reza Vossoughi 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
Modeling the spine behavior plays a key role in understanding mechanisms leading to spinal disorders and injuries. The goal of this article is to develop a new model to obtain 3D spine movement patterns. High degrees of freedom of the system, a great many of muscles involved in the spine movements and its unstable intrinsic behavior make the control problem more difficult. New theories in computational motor control suggest optimal control as a useful tool for modeling Central Nervous System (CNS) to provide appropriate control signals while it computes the neural interactions with biological sensors. Therefore, CNS is modeled as an optimal controller. Our simulations illustrate the movement behavior and muscles force patterns which may be used to relate to the risk of injury in both joints and muscles.
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