Effect Of Structural Deformation Research Articles

공탄성 변형효과를 고려한 5MW급 풍력발전 블레이드의 피치각에 따른 성능해석

In this study, performance analyses have been conducted for a 5㎿ class wind turbine blade model. Advanced computational analysis system based on computational fluid dynamics(CFD) and computational structural dynamics(CSD) has been developed in order to investigate detailed dynamic responsed of wind turbine blade. Reynolds-averaged Navier-Stokes (RANS) equations with K- turbulence model are solved for unsteady flow problems of the rotating turbine blade model. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3D turbine blade for fluid-structure interaction (FSI) problems. Predicted aerodynamic performance considering structural deformation effect of the blade show different results compared to the case of rigid blade model.

비대칭 장력 모델을 이용한 예인 물체의 유체-구조 상호작용 모사

The fluid-structure interaction of a towed body is simulated using a developed code, which is based on the flux-difference splitting scheme on the hybrid Cartesian/immersed boundary method. To improve the stability in the coupling between the fluid and structure domains, a scheme is used, in which the effects of structure deformation are treated implicitly. The developed code is validated for the fluid-structure interaction problem through comparisons with other results on the vortex-induced vibration of elastically mounted cylinders. To simulate behavior of a towed body, an asymmetric tension modelling for a towing cable is suggested. In the suggested model, the tension is proportional to the elongation of the cable, but the cable has no effect on the body motion whenever the distance between the endpoints of the cable is smaller than the original length of the cable. The fluid-structure interactions of a towed body are simulated on the basis of different parameters of the towing cables. It is observed that the suggested tension model predicts the snapping for a shorter towing cable, which is in accordance with the reported results.

Thermal and Structural Analysis of Interaction Cavity and Its Effect on the Operating Mode Excitation for a 120 GHz, 1 MW Gyrotron

Thermal and structural analysis for a 120 GHz, 1 MW gyrotron interaction cavity and the effect of structural deformation on the operational mode excitation is presented. Finite element analysis codes ANSYS and COSMOS have been used for the thermal and structural simulation. The values of the water flow rate and the hydraulic diameter of the outer jacket have been optimized. The effect of the maximum radial expansion of the interaction cavity on eigenfrequency and mode excitation has also been analyzed. The change in eigenfrequency for the operating mode due to thermal expansion is 0.606 GHz. This value is very near the theoretically calculated value and under the tolerance limit of the maximum frequency deviation for the gyrotron operating mode.

Preliminary study of a niobium quarter-wave prototype cavity for a heavy-ion superconducting linac

Superconducting quarter-wave resonators, due to their compactness and their convenient shape for tuning and coupling, are very attractive for low-β beam acceleration. In this paper, two types of cavities with different geometry have been numerically simulated: the first type with larger capacitive load in the beam line and the second type of lollipop-shape for 100 MHz, β=0.06 beams; then the relative electromagnetic parameters and geometric sizes have been compared. It is found that the second type, whose structural design is optimized with the conical stem and shaping drift-tube, can support the better accelerating performance. At the end of the paper, some structural deformation effects on frequency shifts and appropriate solutions have been discussed.

Effects of structural deformation on formation of coalbed methane reservoirs in Huaibei coalfield, China

Tectonically deformed coal is defined as coal formed by superimposed reformations from tectonic stress. The Huaibei coalfield is typically composed of various tectonically deformed coals containing rich coalbed methane resources. However, the occurrence of coal seam in this area is complicated largely by the structural deformation, which has not yet been evaluated systematically for exploration and exploitation of coalbed methane. In this study, tectonism in Huaibei coalfield is discussed by combining systematic analyses on the occurrence of coal seams and the formation of coalbed methane reservoirs. The study shows that, with structural deformation in the study area, the coal seams in Huaibei coalfield are distributed in north–south tectonic blocks and east–west tectonic zones. North tectonic block of Huaibei coalfield is not favourable for exploitation of coalbed methane because of low gas content or disadvantageous structural conditions. Within the south tectonic block, the east Suzhou syncline contains high gas content but coal permeability is very low. This area is generally not suitable for exploitation of coalbed methane and is a dangerous mining area due to gas outburst because of the widely developed mylonitic coals. South Suzhou and Nanping synclines in the middle part of the south tectonic block are exposed to relatively weak structural deformations. These synclines contain coals with high gas content and moderate permeability, which are beneficial for exploration and exploitation of coalbed methane. Linhuan mining area in the south tectonic block is generally not suitable for exploitation of coalbed methane, mainly because of well developed normal faults and interlayer slip structure, and presence of mylonitic coal, resulting in low gas content and poor structural conditions for mining coalbed methane. In contrast, Guoyang mining area in the west part of the south tectonic block, where tectonically deformed coal was generally underdeveloped, is a potential area for exploration and exploitation of coalbed methane because of moderate gas content and possibly higher permeability of its coal.

공력 Buffet 하중을 고려한 헬리콥터 탐색등의 구조진동해석

In this study, computational structural vibration analysis of helicopter search light exposing unsteady buffet load have been conducted using combined advanced numerical methods. Unsteady CFD method based on Navier-Stokes equations is used to predict viscous buffet load due to flow separation effects. Full three-dimensional finite element model is constructed in order to conduct static and structural dynamic analyses of the search light model for two different typical flight speeds. Also, the correct performance of the search light can be physically estimated to examine the actual lighting area considering the effects of structural deformations.

Carbon sequestration in coal-beds with structural deformation effects

Carbon dioxide sequestration in a coal-bed is a profitable method to reduce the concentration of greenhouse gas in the atmosphere and to recover byproduct methane from the coal seam. The important factor to be considered is the stability of the coal-bed with the increased carbon dioxide injection. It is crucial to avoid carbon dioxide escaping from the coal seam caused by structural deformation. Meanwhile, structural deformation also depends on such properties of the geological coal basin as fracture state and phase equilibrium, especially the porosity, permeability and saturation of the coal seam. In this study, a structural deformation effect was simulated with the purpose of predicting carbon dioxide storage in the environment of a typical unmineable coal seam. As an example, Appalachian Basin is considered in the deformation analysis of carbon dioxide sequestration based on the variable saturation model. Moreover, the comparison between simulations with and without the account of structural deformation is given. The results indicate that modeling of structural deformation in carbon sequestration is feasible by directly coupling structure terms to a variable saturated model. Moreover, introducing structural deformation effects into carbon sequestration modeling is important because it affects the fluid flow and leads to a faster drop of the resulting capillary pressure and relative permeability of the gas phase. This faster drop directly results in the diminished carbon dioxide storage capacity in a coal-bed basin. In addition, structural deformation modeling in carbon sequestration simulations can provide important insights into how to avoid carbon leakage and seepage by monitoring the effective stress and displacement of coal-bed basin during carbon dioxide injection.

유동점성 및 공탄성 변형효과를 고려한 스테이터-로터 케스케이드 시스템의 성능평가

본 연구에서는 블레이드 구조 변형 효과를 고려하여 스테이터-로터 상호간섭 케스케이드 모델의 성능평가를 위한 유체-구조 연계해석 시스템을 개발하였다. 고정된 스테이터와 회전하는 로터는 상호간섭 영향이 유동해석에 고려되었으며, 레이놀즈-평균화 난류 방정식인 Spalart-Allmaras 모델과 k-ω SST 난류 모델이 압축성 유동박리 효과를 고려한 유동하중을 예측하기 위해 적용되었다. 정적인 유체-구조 연계해석과 수렴율 증진을 효과적으로 수행하기 위하여 큰 인공 감쇠를 가지는 연계 Newmark 시간적분 기법을 적용하였다. 수치실험을 통해 탄성축 위치에 따른 구조변형 효과가 케스케이드 성능에 미치는 영향을 파악하였다. 구조변형 효과가 고려된 경우 일반적인 강체 블레이드 모델에 대한 성능예측 결과와 다소 차이가 유발될 수 있음을 보였으며 공력탄성학적 영향을 고찰하였다. In this study, advanced (fluid-structure interaction (FSI)) analysis system has been developed in order to predict turbine cascade performance with blade deformation effect due to aerodynamic loads. Intereference effects due to the relative movement of the rotor cascade with respect to the stator cascade are also considered. Reynolds-averaged Navier-Stokes equations with one equation Spalart-Allmaras and two-equation k-ω SST turbulence models are solved to accurately predict fluid dynamic loads considering flow separation effects. A fully implicit time marching scheme based on the (coupled Newmark time-integration method) with high artificial damping is efficiently used to compute the complex fluid-structure interaction problem. Predicted aerodynamic performance considering structural deformation effect of the blade shows somewhat different results compared to the case of rigid blade model. Cascade performance evaluations for different elastic axis positions are importantly presented and its aeroelastic effects are investigated.

Numerical Simulation of a Flapping Foil with Chordwise or Spanwise Flexibility

Motivated by the discovery that living creatures may be able to enhance their locomotion capability through passive or active deformations of their wings or fins, we carry out a fully coupled fluid-structure interaction study to investigate the flapping motion of a foil with either chordwise or spanwise flexibility. We employ a fluid-structure interaction model, which accounts for fluid dynamics using the boundary-element method and structural dynamics using a two-dimensional nonlinear thin-plate model. With this approach, we numerically investigate the effect of structural deformation on the performance of the foil when it is immersed in two different fluids, a low-density fluid (e.g., air), in which the deformation is determined primarily by the inertia of the foil, and a high-density fluid (e.g., water), in which the fluid loading has a significant impact. In the first scenario, we find that the chordwise flexibility reduces both the thrust and the propulsion efficiency and the spanwise flexibility increases the thrust without efficiency reduction within a small range of structural parameters. In the second scenario, we find that the chordwise flexibility increases the efficiency. The spanwise flexibility, on the other hand, compromises the performance of the foil by diminishing both the thrust and the efficiency. Possible applications of these findings and their relation to designs in aquatic animals are discussed.

Electron transfer reaction of Cu(II) porphyrin complex: Effect of structural deformation on the electron self-exchange rate

Homogeneous one-electron oxidation reaction of the sterically constrained nonplanar Cu(II) 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin complex ([Cu(OETPP)]) by Cu 2+ giving the π-cation radical of [Cu(OETPP)] was investigated spectrophotometrically in acetonitrile. The electron self-exchange rate constant of the [Cu(OETPP)] + /0 couple was determined to be 9.3 × 10 3 M −1 s −1 at T = 25.0 °C using the Marcus cross relation for the outer-sphere electron transfer reaction, and the relatively slow self-exchange reaction as compared with those for the planar Cu(II) porphyrin complexes was ascribed to the significant deformation of the complex accompanying the oxidation reaction.

위성체 태양전지판 구조물의 열적 플러터 해석

본 논문에서는 위성체 태양전지의 진동응답을 분석하였다. 태양전지는 복합재료 얇은 벽보와 태양전지 판 및 보조 바로 구성되어 있다. 복합재료 얇은 벽보는 전단 변형, 12차 와핑, 회전 관성과 재료의 방향성 등을 고려해야 한다. 태양전지 판은 z 방향으로 일정한 장력이 가해지는 얇은 막이며 보조 바는 강체 구조물이다. 열적 구배에 따른 구조 변형에 의한 영향을 고려하여 연성된 열적 구조 해석을 수행하였으며, 열적 불안정성 조건이 되는 안정성 기준 인자들을 분석하였다. In this paper, the vibration response of the spacecraft solar array is investigated. The solar array model consists of composite thin walled beam and solar blanket, spreader bar. The composite thin walled beam incorporates a number of nonclassical effects of transverse shear, primary and secondary warping, rotary inertia and anisotropy of constituent materials. The solar blanket is a membrane subjected to uniform tension in the z direction. The spreader bar is a rigid member. A coupled thermal structure analysis that includes the effects of structural deformations on heating and temperature gradient is investigated. A stability criterion given in parameters for establishes the conditions for thermal flutter.

Investigation of a 3-D hybrid finite-element/boundary-element method for electromagnetic launch applications and validation using semianalytical solutions

The hybrid finite element/boundary element (FE/BE) computational scheme is advantageous in that it satisfies boundary conditions at infinity while avoiding meshing and computations in the air regions. Of numerous hybrid schemes, one using the fundamental solution of Poisson's equation as the weighting function has been employed successfully in many fields. Analyses in electromagnetic (EM) launch usually involve strong coupling among EM, thermal, and structural equations. The hybrid method has the added benefit that it may be fashioned to incorporate the effect of structural deformations on EM fields. Here, a three-dimensional (3D) hybrid algorithm using the fundamental solution of Poisson's equation as the weighting function is investigated and implemented in the parallel version of the code electromechanical analysis program in 3D (EMAP3D). The method is validated using two examples with semianalytical solutions: a 3D ring conductor with rectangular cross section carrying uniform current, and a quadrupole configuration with four independent, closed-ring conductors excited by imposed potential differences. The solutions obtained using the hybrid method match the semianalytical solutions within approximately four percent deviations.

Effects of the structural deformations on the magnetism of Rh 6 and Rh 13 clusters

The effect of structural deformations on the magnetic and electronic properties of small Rh clusters was studied. The electronic properties were calculated using a self-consistent spd tight-binding Hamiltonian within the unrestricted Hartree–Fock approximation. For hydrostatic deformations, the magnetic moment of the clusters increases with bond-length in a steplike fashion. Axial distortions, on the other hand, affect the magnetism of the clusters in a more complex manner that can be correlated with the local coordination and bond length through the definition of an effective coordination number.

Electronic transport through carbon nanotubes: effects of structural deformation and tube chirality.

Atomistic simulations using a combination of classical force field and density-functional theory (DFT) show that carbon atoms remain essentially sp(2) coordinated in either bent tubes or tubes pushed by an atomically sharp atomic-force microscope (AFM) tip. Subsequent Green's-function-based transport calculations reveal that for armchair tubes there is no significant drop in conductance, while for zigzag tubes the conductance can drop by several orders of magnitude in AFM-pushed tubes. The effect can be attributed to simple stretching of the tube under tip deformation, which opens up an energy gap at the Fermi surface.

Structural effects on the magnetic properties of elementary cubic networks of Josephson junctions

A general analytic approach to the study of structural deformation effects on the electrodynamic properties of elementary cubic networks of Josephson junctions (JJs) is presented. The undeformed network consists of twelve JJs interrupting the edges of a superconducting cubic structure. By first order perturbation analysis on the deformation parameters it is shown that, as in the unperturbed case, for well defined applied field orientations, the voltage vs. applied magnetic flux curves present a period which can be an uncommensurate multiple of the elementary flux quantum.

EFFECTS OF FILTERING THE ANGULAR MOTION OF THE CRANKSHAFT ON THE ESTIMATION OF THE INSTANTANEOUS ENGINE FRICTION TORQUE

The focus of this study is to investigate the effects of filtering the actual angular displacement, velocity and acceleration of the crankshaft on the computation of the instantaneous engine friction torque. These effects are isolated from those of measurement errors and/or noise by relying on a detailed model of the crank-slider mechanism to generate the rigid and flexible motions of the piston/connecting-rod/crankshaft mechanism along with the engine friction torque. The (P−ω) method is used herein to estimate the instantaneous engine friction torque based on the actual and the filtered angular displacement, velocity and acceleration of the crankshaft. The digital simulation results have demonstrated that the (P−ω) method cannot produce an acceptable estimation of the instantaneous engine friction torque in spite of filtering the actual angular motion of the crankshaft. It should be mentioned that the low-pass filter is commonly implemented to attenuate the measurement noise and the effects of structural deformations on the measured angular velocity of the crankshaft. However, the ineffectiveness of the low-pass filter stems from the non-linearities of the crank-slider mechanism that induced superharmonic and combination resonance frequencies in the angular displacement, velocity and acceleration of the crankshaft. The filter has severely attenuated some of the superharmonic resonance frequencies, which constitute an important part of the rigid-body behavior of the crankshaft that is needed by the (P−ω) method to accurately predict the engine friction torque. Moreover, the filtered signals would still be contaminated by the combination resonance frequencies that may appear in the low-frequency range commonly assumed to be dominated by the frequency components of the rigid-body motion of the crankshaft.

EFFECTS OF STRUCTURAL DEFORMATIONS OF THE CRANK-SLIDER MECHANISM ON THE ESTIMATION OF THE INSTANTANEOUS ENGINE FRICTION TORQUE

The focus on the current study is to assess the effects of structural deformations of the crankshaft/connecting-rod/piston mechanism on the computation of the instantaneous engine friction torque. This study is performed in a fully controlled environment in order to isolate the effects of structural deformations from those of measurement errors or noise interference. Therefore, a detailed model, accounting for the rigid and flexible motions of the crank-slider mechanism and including engine component friction formulations, is considered in this study. The model is used as a test bed to generate the engine friction torque,Tfa, and to predict the rigid and flexible motions of the system in response to the cylinder gas pressure. The torsional vibrations and the rigid body angular velocity of the crankshaft, as predicted by the detailed model of the crank-slider mechanism, are used along with the engine load torque and the cylinder gas pressure in the (P–ω) method to estimate the engine friction torque,Tfe. This method is well suited for the purpose of this study because its formulation is based on the rigid body model of the crank-slider mechanism. The digital simulation results demonstrate that the exclusion of the structural deformations of the crank-slider mechanism from the formulation of the (P–ω) method leads to an overestimation of the engine friction torque near the top-dead-center (TDC) position of the piston under firing conditions. Moreover, for the remainder of the engine cycle, the estimated friction torque exhibits large oscillations and takes on positive numerical values as if it is inducing energy into the system. Thus, the adverse effects of structural deformations of the crank-slider mechanism on the estimation of the engine friction torque greatly differ in their nature from one phase of the engine cycle to another.

Ab initiostudy on the molecular recognition by metalloporphyrins: CO interaction with iron porphyrin

We have performed ab initio pseudopotential calculations to study the effects of structural deformations of iron porphyrin on the configuration of a carbon monoxide ~CO! attached to it. We have considered two proximal deformations around the heme group: ~i! rotation of a pyrrole ring in the iron porphyrin, and ~ii! rotation of the imidazole side chain bound to the iron atom. We have identified induced changes of the atomic geometry and the electronic structure of the iron porphyrin‐CO complex, and the results elucidate the microscopic nature of the CO interaction with the iron porphyrin. Implications on the controversies over the binding angle of the CO molecule on the iron porphyrin under different circumstances are discussed. A potential application to the simulation-based chemical sensor design is also discussed. @S1063-651X~99!10002-3#

The Metallography of Deformation by Material Removal / Metallographische Untersuchung der Verformung durch Materialabtrag

This study concerns the mechanism of material removal and how it affects the structure of the machined component. Deformation severity is related to the different techniques available for material removal. Grain growth due to heat generated during abrasive sectioning has been demonstrated. Through the utilisation of microindentation, supported by microstructural analysis, it has been shown how phase migration is an additional consideration when mechanically working ductile material surfaces. Finally an assessment of the effect of structural deformation on component life is made. From this work the relationship of deformation by material removal mechanisms are related to surface preparation for microstructural analysis.

Thermally induced bending vibrations of a flexible rolled-up solar array

An analytical approach for determining the thermal-structural response of a flexible rolled-up solar array due to a sudden increase in external heating is developed. Two analyses are presented: 1) an uncoupled thermal-structural analysis that assumes the heating and temperature gradients are not affected by thermally induced motions, and 2) a coupled thermal-structural analysis that includes the effects of structural deformations on heating and temperature gradients. The analytical methods identify key parameters for understanding the static and dynamic response. A stability criterion given in nondimensional parameters establishes the conditions for thermal flutter. Key parameters for thermal flutter include the ratio of thermal and structural response times, the solar inclination angle, and the system damping. Numerical calculations are presented for the solar arrays on the Hubble Space Telescope. Unstable oscillations are possible but are unlikely to have practical importance.