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RISS 인기검색어
- 검색키워드
- 저자 : Khaled Farah (검색결과 3 건)
- 무료
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Beam finite element model of a vibrate wind blade in large elastic deformation
Hedi Hamdi,Khaled Farah 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.26 No.1
This paper presents a beam finite element model of a vibrate wind blade in large elastic deformation subjected to the aerodynamic, centrifugal, gyroscopic and gravity loads. The gyroscopic loads applied to the blade are induced by her simultaneous vibration and rotation. The proposed beam finite element model is based on a simplex interpolation method and it is mainly intended to the numerical analysis of wind blades vibration in large elastic deformation. For this purpose, the theory of the sheared beams and the finite element method are combined to develop the algebraic equations system governing the three-dimensional motion of blade vibration. The applicability of the theoretical approach is elucidated through an original case study. Also, the static deformation of the used wind blade is assessed by appropriate software using a solid finite element model in order to show the effectiveness of the obtained results. To simulate the nonlinear dynamic response of wind blade, the predictor-corrector Newmark scheme is applied and the stability of numerical process is approved during a large time of blade functioning. Finally, the influence of the modified geometrical stiffness on the amplitudes and frequencies of the wind blade vibration induced by the sinusoidal excitation of gravity is analyzed.
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Beam finite element model of a vibrate wind blade in large elastic deformation
Hamdi, Hedi,Farah, Khaled Techno-Press 2018 Wind and Structures, An International Journal (WAS Vol.26 No.1
This paper presents a beam finite element model of a vibrate wind blade in large elastic deformation subjected to the aerodynamic, centrifugal, gyroscopic and gravity loads. The gyroscopic loads applied to the blade are induced by her simultaneous vibration and rotation. The proposed beam finite element model is based on a simplex interpolation method and it is mainly intended to the numerical analysis of wind blades vibration in large elastic deformation. For this purpose, the theory of the sheared beams and the finite element method are combined to develop the algebraic equations system governing the three-dimensional motion of blade vibration. The applicability of the theoretical approach is elucidated through an original case study. Also, the static deformation of the used wind blade is assessed by appropriate software using a solid finite element model in order to show the effectiveness of the obtained results. To simulate the nonlinear dynamic response of wind blade, the predictor-corrector Newmark scheme is applied and the stability of numerical process is approved during a large time of blade functioning. Finally, the influence of the modified geometrical stiffness on the amplitudes and frequencies of the wind blade vibration induced by the sinusoidal excitation of gravity is analyzed.
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FTIR study of gamma and electron irradiated high-density polyethylene for high dose measurements
Hanan Al-Ghamdi,Khaled Farah,Aljawharah Almuqrin,Faouzi Hosni 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1
A reliable and well-characterized dosimetry system which is traceable to the international measurementsystem, is the key element to quality assurance in radiation processing with cobalt-60 gamma rays, Xrays,and electron beam. This is specifically the case for health-regulated processes, such as the radiationsterilization of single use medical devices and food irradiation for preservation and disinfestation. Polyethylene is considered to possess a lot of interesting dosimetric characteristics. In this work, adetailed study has been performed to determine the dosimetric characteristics of a commercialized highdensitypolyethylene (HDPE) film using Fourier transformed infrared spectrometry (FTIR). Correlationshave been established between the absorbed dose and radiation induced infrared absorption in polyethylenehaving a maximum at 965 cm 1 (transvinylene band) and 1716 cm 1 (ketone-carbonyl band). We have found that polyethylene dose-response is linear with dose for both bands up to1000 kGy. Fortransvinylene band, the dose-response is more sensitive if irradiations are made in helium. While, forketone-carbonyl band, the dose-response is more sensitive when irradiations are carried out in air. Thedose-rate effect has been found to be negligible when polyethylene samples are irradiated with electronbeam high dose rates. The irradiated polyethylene is relatively stable for several weeks after irradiation.
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