Relevant bibliographies by topics / Flat and curved panels

Academic literature on the topic 'Flat and curved panels'

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Published: 6 September 2023

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Journal articles on the topic "Flat and curved panels"

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Szelag, Agata, Tadeusz Kamisiński, Mirosława Lewińska, Jarosław Rubacha, and Adam Pilch. "The Characteristic of Sound Reflections from Curved Reflective Panels." Archives of Acoustics 39, no. 4 (March 1, 2015): 549–58. http://dx.doi.org/10.2478/aoa-2014-0059.

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Abstract The paper presents the verification of a solution to the narrow sound frequency range problem of flat reflective panels. The analytical, numerical and experimental studies concerned flat panels, panels with curved edges and also semicircular elements. There were compared the characteristics of sound reflected from the studied elements in order to verify which panel will provide effective sound reflection and also scattering in the required band of higher frequencies, i.e. above the upper limit frequency. Based on the conducted analyzes, it was found that among some presented solutions to narrow sound frequency range problem, the array composed of panels with curved edges is the most preferred one. Nevertheless, its reflection characteristic does not meet all of the requirements, therefore, it is necessary to search for another solution of canopy which is effective over a wide frequency range.
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SAHU, S. K., and A. V. ASHA. "PARAMETRIC RESONANCE CHARACTERISTICS OF ANGLE-PLY TWISTED CURVED PANELS." International Journal of Structural Stability and Dynamics 08, no. 01 (March 2008): 61–76. http://dx.doi.org/10.1142/s0219455408002557.

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The present study deals with the dynamic stability of laminated composite pre-twisted cantilever panels. The effects of various parameters on the principal instability regions are studied using Bolotin's approach and finite element method. The first-order shear deformation theory is used to model the twisted curved panels, considering the effects of transverse shear deformation and rotary inertia. The results on the dynamic stability studies of the laminated composite pre-twisted panels suggest that the onset of instability occurs earlier and the width of dynamic instability regions increase with introduction of twist in the panel. The instability occurs later for square than rectangular twisted panels. The onset of instability occurs later for pre-twisted cylindrical panels than the flat panels due to addition of curvature. However, the spherical pre-twisted panels show small increase of nondimensional excitation frequency.
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Pany, C., and S. Parthan. "Axial Wave Propagation in Infinitely Long Periodic Curved Panels." Journal of Vibration and Acoustics 125, no. 1 (January 1, 2003): 24–30. http://dx.doi.org/10.1115/1.1526510.

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Propagation of waves along the axis of the cylindrically curved panels of infinite length, supported at regular intervals is considered in this paper to determine their natural frequencies in bending vibration. Two approximate methods of analysis are presented. In the first, bending deflections in the form of beam functions and sinusoidal modes are used to obtain the propagation constant curves. In the second method high precision triangular finite elements is used combined with a wave approach to determine the natural frequencies. It is shown that by this approach the order of the resulting matrices in the FEM is considerably reduced leading to a significant decrease in computational effect. Curves of propagation constant versus natural frequencies have been obtained for axial wave propagation of a multi supported curved panel of infinite length. From these curves, frequencies of a finite multi supported curved panel of k segments may be obtained by simply reading off the frequencies corresponding to jπ/kj=1,2…k. Bounding frequencies and bounding modes of the multi supported curved panels have been identified. It reveals that the bounding modes are similar to periodic flat panel case. Wherever possible the numerical results have been compared with those obtained independently from finite element analysis and/or results available in the literature.
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Zhou, Jian, Minglong Xu, and Zhichun Yang. "Nonlinear Flutter Response of Heated Curved Composite Panels with Embedded Macrofiber Composite Actuators." Advances in Materials Science and Engineering 2018 (December 26, 2018): 1–12. http://dx.doi.org/10.1155/2018/3103250.

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The nonlinear flutter response of heated curved composite panels with embedded macrofiber composite (MFC) actuators in supersonic airflow is investigated. Prescribed voltages are statically applied to the piezoelectric actuators, inducing a prestress field which results in an additional stiffness effect on the curved panel, and it will change the aeroelastic behavior of curved composite panels. The aeroelastic equations of curved composite panels with embedded MFC actuators are formulated by the finite element approach. The von Karman large deflection panel theory and the first-order piston theory aerodynamics are adopted in the formulation. The motion equations are solved by a fourth-order Runge–Kutta numerical scheme, and time history, phase portrait, Poincaré map, bifurcation diagram, and Lyapunov exponent are used for better understanding of the pre/postflutter responses. The results demonstrate that the nonlinear flutter response characteristics of the curved panel differs from those of the flat panels significantly, and the transverse displacement of the curved composite panels with embedded MFC actuators in the preflutter region shows a gradual static displacement; the chaotic motions occur directly after static motion because of the effect of the temperature elevation. The applied voltages can increase the critical dynamic pressure and change the bifurcation diagram of the curved composite panels with embedded MFC actuators, and the response amplitudes can be reduced evidently.
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Zhang, Y., and F. L. Matthews. "Large Deflection Behavior of Simply Supported Laminated Panels Under In-Plane Loading." Journal of Applied Mechanics 52, no. 3 (September 1, 1985): 553–58. http://dx.doi.org/10.1115/1.3169100.

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An analysis is presented for nonbifurcational behavior of flat and curved panels of unsymmetrically laminated composite materials under in-plane loading, either compression or shear. A pair of governing equations in the von Karman sense are solved in conjunction with simply supported boundaries. A series of computations is carried out for panels having different curvatures, different lay-ups, and different materials. The results show that during loading, lateral deflection is involved in panels with unsymmetric cross-ply layers under compression or in those with unsymmetric angle-ply layers under shear. This effect increases deflection of the flat plates under loading and reduces resistance of curved panels against collapse.
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Bates, Trent P., Ian C. Bacon, Scott D. Sommerfeldt, and Jonathan D. Blotter. "Experimental and numerical validation of vibration-based sound power measurements of arbitrarily curved panels." Journal of the Acoustical Society of America 150, no. 4 (October 2021): A344. http://dx.doi.org/10.1121/10.0008529.

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Vibration-based sound power (VBSP) measurement methods are of interest due to their potential versatility in application compared to methods based on sound-pressure or sound-intensity. The VBSP method is based on the elementary radiator approach that relies on the acoustic radiation resistance matrix. Previous work has validated the form of the radiation resistance matrix for flat plates, cylindrical- and spherical-shells, and simple-curved plates. A form specific to arbitrarily curved structures has not been developed. Experimental VBSP measurements of two arbitrarily curved panels are shown to have excellent agreement with results from the ISO 3741 method. The VBSP method was applied by using the simple-curved plate form of the radiation resistance matrix and mapping each arbitrarily curved panel with a constant-radius curve fit. Numerical boundary element models, that inherently use the true form of the radiation resistance matrix, were also used to compute the sound power from the same curved panels. Surface velocity data from the numerical models were used to also compute sound power using the VBSP method with the simple-curved plate form of the radiation resistance matrix. Sound power results show excellent agreement between the numerical model and VBSP method. [Work supported by the National Science Foundation.]
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Yurddaskal, Melis, and Buket Okutan Baba. "Experimental and numerical analysis of vibration frequency in sandwich composites with different radii of curvature." Journal of Sandwich Structures & Materials 21, no. 8 (August 29, 2017): 2870–86. http://dx.doi.org/10.1177/1099636217728009.

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In this study, free vibration responses of sandwich composite panels with different radius of curvature were presented numerically. The studies were carried out on square flat and curved sandwich panels made of E-glass/epoxy face sheets and polyvinyl chloride foam with three different radii of curvature. Experimental studies were used to verify the numerical results. Vibration tests were performed on flat and curved sandwich panels under free–free boundary conditions. The experimental data were then compared with finite element simulation, which was conducted by ANSYS finite element software and it was shown that the numerical analysis results agree well with the experimental ones. Effect of the curvature on natural frequencies under different boundary conditions (all edge free, simply supported, and fully clamped) was investigated numerically. Results indicated that the natural frequencies and corresponding mode shapes were affected by boundary conditions and curvature of the panel. For all boundary conditions, the variation of curvature had smaller effect on the natural frequency of the first mode than those of the other modes.
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Bartha, Michael C., Paul Allie, and Doug Kokot. "Field Observations of Placement for Large-Panel Flat and Curved Displays for Presbyopic and Prepresbyopic Computer Users." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 64, no. 1 (December 2020): 526–30. http://dx.doi.org/10.1177/1071181320641119.

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Displays with panels larger than 30 inches are being provided to workers in corporate settings at an increasing rate. Additionally, some models are offered that have curved panels. This field study was designed to observe user selected position of 34 inch curved and flat displays and determine if there are positioning, user experience and satisfaction differences between pre-presbyopes and presbyope workers who have multifocal vision correction. The results indicate that participants position larger displays a little farther away than displays with a less than 30 inch diagonal. Newer, larger displays did not reduce reports of eye discomfort, but they did significantly reduce reports of neck and shoulder discomfort. Study participants preferred working with the curved display compared to the large flat display.
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Pirzada, Luqman Ahmed, Xiaoli Wu ., Qaiser Ali, and Asif Khateeb . "Investigation of Performance of Solar Flat and Curved Plate Collectors through Numerical Simulations." January 2021 40, no. 1 (January 1, 2021): 66–74. http://dx.doi.org/10.22581/muet1982.2101.06.

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Solar energy is radiant light as a form of thermal heat energy which can be obtained and used by means of a variety of solar apparatus. As apparatus the flat and curved plate solar collector is specifically designed for assembling solar energy as a solar water heater system. The designing potency of this collector lone can generate medium level hot water from radiant sunlight source via absorbed plates. Standard type flat and curved plates solar collector plates are mostly used in remote coldest regions of the world where hot water is consumed for commercial and domestic purposes. These types of solar collector Plates can cheaply be manufactured compared to other solar panels like solar Shingles, Polycrystalline Solar Panels, Mono-crystalline Solar Panels, and Thin Film Solar Panels. For future work, this proposed pre-design is recommended for fabrication. A numerical study was carried-out on eight city locations in China by tracing their horizontal and vertical longitudinal, latitudinal lines noting the date, time and sunlight feeding of temperatures in the Celsius scale with the help of simulation and modeling tools like CFD, ANSYS FLUENT software, mesh geometry tools, and by using the Navier-Stokes and Continuity equations by fluid flow discharge rate, mass flow, water temperature and dropping of temperature, radiation working mechanisms, dimensions of water flowing tubes and absorber plates, density, the velocity of water as the working fluid, the viscosity of water in a cold and hot state as a process of Pre-design. Work also focuses on the comparison between flat plate collector and curved plate collector radiant sunlight absorption, As end result it is found the Curved plate collector produces 22% more elevated heat of outgoing water than flat plate collector.
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De Luca, Alessandro, Donato Perfetto, Antonio Polverino, Antonio Aversano, and Francesco Caputo. "Finite Element Modeling Approaches, Experimentally Assessed, for the Simulation of Guided Wave Propagation in Composites." Sustainability 14, no. 11 (June 6, 2022): 6924. http://dx.doi.org/10.3390/su14116924.

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Today, structural health monitoring (SHM) systems based on guided wave (GW) propagation represent an effective methodology for understating the structural integrity of primary and secondary structures, also made of composite materials. However, the sensitivity to damage detection promoted by these systems can be altered by such factors as the geometry of the monitored parts, as well as the environmental and operational conditions (EOCs). Experimental investigations are fundamental but require a long time period and are costly, especially for tests in real-life scenarios. Experimentally validated simulations can help designers to improve SHM effectiveness due to the possibility of further broadening study on the different geometries, load cases, and material types with less effort. From this point of view, this paper presents two finite element (FE) modeling approaches for the simulation of GW propagation in composite panels. The case study consists of a flat and a curved composite panel. The two approaches herein investigated are based on implicit and explicit finite element analysis (FEA) formulations. The comparison of the predicted measures against the experimental dataset allowed the assessment of the levels of accuracy provided by both modeling approaches with respect to the dispersion curves. Furthermore, to assess the different curvature sensitivities of the proposed numerical and experimental approaches, the extracted dispersion curves for both flat and curved panels were compared.
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Dissertations / Theses on the topic "Flat and curved panels"

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Hause, Terry J. "Thermomechanical Postbuckling of Geometrically Imperfect Anisotropic Flat and Doubly Curved Sandwich Panels." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30449.

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Sandwich structures constitute basic components of advanced supersonic/hypersonic flight and launch vehicles. These advanced flight vehicles operate in hostile environments consisting of high temperature, moisture, and pressure fields. As a result, these structures are exposed to large lateral pressures, large compressive edge loads, and high temperature gradients which can create large stresses and strains within the structure and can produce the instability of the structure. This creates the need for a better understanding of the behavior of these structures under these complex loading conditions. Moreover, a better understanding of the load carrying capacity of sandwich structures constitutes an essential step towards a more rational design and exploitation of these constructions. In order to address these issues, a comprehensive geometrically non-linear theory of doubly curved sandwich structures constructed of anisotropic laminated face sheets with an orthotropic core under various loadings for simply supported edge conditions is developed. The effects of the radii of curvature, initial geometric imperfections, pressure, uniaxial compressive edge loads, biaxial edge loading consisting of compressive/tensile edge loads, and thermal loads will be analyzed. The effect of the structural tailoring of the facesheets upon the load carrying capacity of the structure under these various loading conditions are analyzed. In addition, the movability/immovability of the unloaded edges and the end-shortening are examined. To pursue this study, two different formulations of the theory are developed. One of these formulations is referred to as the mixed formulation, While the second formulation is referred to as the displacement formulation. Several results are presented encompassing buckling, postbuckling, and stress/strain analysis in conjunction with the application of the structural tailoring technique. The great effects of this technique are explored. Moreover, comparisons with the available theoretical and experimental results are presented and good agreements are reported.
Ph. D.
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Lin, Weiqing. "Buckling and postbuckling of flat and curved laminated composite panels under thermomechanical loadings incorporating non-classical effects." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/40240.

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Two structural models which can be used to predict the buckling, post buckling and vibration behavior of flat and curved composite panels under thermomechanical loadings are developed in this work. Both models are based on higher-order transverse shear deformation theories of shallow shells that include the effects of geometric nonlinearities and initial geometric imperfections. Within the first model (Model I), the kinematic continuity at the contact surfaces between the contiguous layers and the free shear traction condition on the outer bounding surfaces are satisfied, whereas in the second model (Model II), in addition to these conditions, the static interlaminae continuity requirement is also fulfilled. Based on the two models, results which cover a variety of problems concerning the postbuckling behaviors of flat and curved composite panels are obtained and displayed. These problems include: i) buckling and postbuckling behavior of flat and curved laminated structures subjected to mechanical and thermal loadings; ii)frequency-load/temperature interaction in laminated structures in both pre-buckling and post buckling range; iii) the influence of a linear/nonlinear elastic foundation on static and dynamic post buckling behavior of flat/curved laminated structures exposed to mechanical and temperature fields; iv) implication of edge constraints upon the temperature/load carrying capacity and frequencyload/ temperature interaction of flat/curved structures; v) elaboration of a number of methodologies enabling one to attenuate the intensity of the snap-through buckling and even to suppress it as well as of appropriate ways enabling one to enhance the load/temperature carrying capacity of structures.
Ph. D.
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Nourzad, Delphine. "Active vibration control of doubly-curved panels." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/363620/.

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This thesis considers active control of the vibration of doubly-curved panels. Such panels are widely used in vehicles such as cars and aircraft, whose vibration is becoming more problematic as the weight of these vehicles is reduced to control their CO2 emissions. The dynamic properties of doubly-curved panels are first considered and an analytic model which includes in-plane inertia is introduced. The results of this analytical model are compared with those from numerical modelling. Of particular note is the clustering of lower-order modes as the curvature becomes more significant. The influence of these changes in dynamics is then studied by simulating the performance of a velocity feedback controller using an inertial actuator. The feasibility of implementing such an active control system on a car roof panel is then assessed. Experiments and simulations are also conducted on a panel, mounted on one side of a rigid enclosure, which is curved by pressurising the enclosure. The active control of vibration on this panel is then implemented using compensated velocity feedback control and novel inertial actuators. It is found that the performance of the feedback control initially improves as the curvature increases, since the fundamental natural frequency of the panel becomes larger compared with the actuator resonance frequency, but then the performance is significantly degraded for higher levels of curvature, since the natural frequencies of many of the panel modes cluster together. Finally, the integration of a compensator filter in the control system ensures the robustness of the system, despite changes in curvature, which makes it a good candidate for future multi-channel implementations.
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Breivik, Nicole L. "Thermal and Mechanical Response of Curved Composite Panels." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/28015.

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Curved panels constructed of laminated graphite-epoxy composite material are of potential interest in airframe fuselage applications. An understanding of structural response at elevated temperatures is required for anticipated future high speed aircraft applications. This study concentrates on the response of unstiffened, curved composite panels subjected to combinations of thermal and mechanical loading conditions. Mechanical loading is due to compressive end-shortening and thermal loading is due to a uniform temperature increase. Thermal stresses, which are induced by mechanical restraints against thermal expansions or contractions, cause buckling and postbuckling panel responses. Panels with three different lamination sequences are considered, including a quasi-isotropic laminate, an axially soft laminate, and an axially stiff laminate. These panels were chosen because they exhibit a range of stiffnesses and a wide variation in laminate coefficients of thermal expansion. The panels have dimensions of 10 in. by 10 in. with a base radius of 60 in. The base boundary conditions are clamped along the curved ends, and simply supported along the straight edges. Three methods are employed to study the panel response, including a geometrically nonlinear Rayleigh-Ritz solution, a finite element solution using the commercially available code STAGS, and an experimental program. The effects of inplane boundary conditions and radius of curvature are studied analytically, along with consideration of order of application in combined loading. A substantial difference is noted in the nonlinear load vs. axial strain responses of panels loaded in end-shortening and panels loaded with uniform temperature change, depending on the specific lamination sequence, boundary conditions, and radius of curvature. Experiments are conducted and results are presented for both room temperature end-shortening tests and elevated temperature tests with accompanying end-shortening. The base finite element model is modified to include measured panel thicknesses, boundary conditions representative of the experimental apparatus, measured initial geometric imperfections, and measured temperature gradients. With these modifications, and including an inherent end displacement of the panel present during thermal loading, good correlation is obtained between the experimental and numerically predicted load vs. axial strain responses from initial loading through postbuckling.
Ph. D.
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Gao, Yifei. "Response of Curved Composite Panels under External Blast." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1404084105.

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Millner, Anthony. "Noncommutative phenomena in flat and curved space-times." Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/4910.

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Includes bibliographical references (leaves 88-92).
This thesis aims to explore several facets of noncommutative geometry which arise in physics. In particular, our focus will be on string-inspired noncommutativity, and we will at all times try to justify the noncommutative models we study from a stringy perspective.
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Jenkins, Staci Nicole 1975. "Investigation of curved composite panels under high-g loading." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/50077.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1999.
Includes bibliographical references (p. 129-133).
Numerical and experimental work was conducted to investigate the use of composites within the Wide Area Surveillance Projectile (WASP) wing system by specifically studying the buckling behavior of curved composite panels under high-g loading. A finite element model was developed as a design tool to model the original WASP wing as a constant thickness curved panel and to predict the buckling response of the panels. The model predicted the critical buckling loads and mode shapes of the composite panels. Experimentally, controlled axial compression tests and high-g tests were performed to determine the buckling response of the panels. The buckling response, including critical loads and mode shapes, was obtained for the controlled axial compression tests. The high-g tests demonstrated that composite panels are a viable option for structures in a high-g environment. All of the samples tested showed no signs of damage and no loss in load carrying capability. The results were used to study the effect of lay-up, curvature, aspect ratio (width to height), and height on the buckling response. The results of the finite element model and the controlled axial compression tests showed good agreement. However, they do not accurately capture the buckling response of the composite panels in the high-g environment.
by Staci Nicole Jenkins.
S.M.
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Gattas, Joseph M. "Quasi-static impact of foldcore sandwich panels." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:d6cca0fd-f5e4-4df4-88e3-8f05af5e6db1.

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This thesis considered the design of new and improved foldcore sandwich panels suitable for high-performance energy absorption applications. This was achieved by utilising origami geometry design techniques to alter foldcore structures such that they possessed different mechanical behaviours and failure modes. The major findings of this thesis were in three areas as follows. First, a modified planar foldcore geometry was developed by introducing sub-folds into a standard foldcore pattern. The new geometry, deemed the indented foldcore, successfully triggered a high-order failure mode known as a travelling hinge line failure mode. This was found to have a much higher energy absorption than the plate buckling failure mode seen in an unmodified foldcore structure. A comprehensive numerical, theoretical, and experimental analysis was conducted on the indented core, which included the development of a new foldcore prototyping method that utilised 3D printed moulds. It was shown that compared to available commercial honeycomb cores, the indented foldcore had an improved uniformity of energy absorption, but weaker overall peak and crushing stresses. Second, rigid origami design principles were used to develop extended foldcore geometries. New parametrisations were presented for three patterns, to complete a set of Miura-derivative geometries termed first-level derivatives. The first-level derivative parametrisations were then combined to create complex, piecewise geometries, with compatible faceted sandwich face geometry also developed. Finally, a method to generate rigid-foldable, curved-crease geometry from Miura-derivative straight-crease geometry was presented. All geometry was validated with physical prototypes and was compiled into a MATLAB Toolbox. Third, the performance of these extended foldcore geometries under impact loadings was investigated. An investigation of curved-crease foldcores showed that they were stronger than straight-crease foldcores, and at certain configurations can potentially match the strength, energy-absorption under quasi-static impact loads, and out-of-plane stiffness of a honeycomb core. A brief investigation of foldcores under low-velocity impact loadings showed that curved-crease foldcores, unlike straight-crease foldcores, strengthened under dynamic loadings, however not to the same extent as honeycomb. Finally, an investigation of single-curved foldcore sandwich shells was conducted. It was seen that foldcore shells could not match the energy-absorption capability of an over-expanded honeycomb shell, but certain core types did exhibit other attributes that might be exploitable with future research, including superior initial strength and superior uniformity of response.
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Schrader, Lars-Uve. "Receptivity of Boundary-Layer Flows over Flat and Curved Walls." Doctoral thesis, KTH, Stabilitet, Transition, Kontroll, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-25439.

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Direct numerical simulations of the receptivity and instability of boundary layers on flat and curved surfaces are herein reported. Various flow models are considered with the aim to capture aspects of flows over straight and swept wings such as wall curvature, pressure variations, leading-edge effects, streamline curvature and crossflow. The first model problem presented, the flow over a swept flat plate, features a crossflow inside the boundary layer. The layer is unstable to steady and traveling crossflow vortices which are nearly aligned with the free stream. Wall roughness and free-stream vortical modes efficiently excite these crossflow modes, and the associated receptivity mechanisms are linear in an environment of low-amplitude perturbations. Receptivity coefficients for roughness elements with various length scales and for free-stream vortical modes with different wavenumbers and frequencies are reported. Key to the receptivity to free-stream vorticity is the upstream excitation of streamwise streaks evolving into crossflow modes. This mechanism is also active in the presence of free-stream turbulence. The second flow model is that of a Görtler boundary layer. This flow type forms on surfaces with concave curvature, e.g. the lower side of a turbine blade. The dominant instability, driven by a vertically varying centrifugal force, appears as pairs of steady, streamwise counter-rotating vortical rolls and streamwise streaks. The Görtler boundary layer is in particular receptive to free-stream vortical modes with zero and low frequencies. The associated mechanism builds on the excitation of upstream disturbance streaks from which the Görtler modes emerge, similar to the mechanism in swept-plate flows. The receptivity to free-stream vorticity can both be linear and nonlinear. In the presence of free-stream turbulence, nonlinear receptivity is more likely to trigger steady Görtler vortices than linear receptivity unless the frequencies of the free-stream fluctuations are very low. The third set of simulations considers the boundary layer on a flat plate with an elliptic leading edge. This study aims to identify the effect of the leading edge on the boundary-layer receptivity to impinging free-stream vortical modes. Three types of modes with streamwise, vertical and spanwise vorticity are considered. The two former types trigger streamwise disturbance streaks while the latter type excites Tollmien-Schlichting wave packets in the shear layer. Simulations with two leading edges of different bluntness demonstrate that the leading-edge shape hardly influences the receptivity to streamwise vortices, whereas it significantly enhances the receptivity to vertical and spanwise vortices. It is shown that the receptivity mechanism to vertical free-stream vorticity involves vortex stretching and tilting - physical processes which are clearly enhanced by blunt leading edges. The last flow configuration studied models an infinite wing at 45 degrees sweep. This model is the least idealized with respect to applications in aerospace engineering. The set-up mimics the wind-tunnel experiments carried out by Saric and coworkers at the Arizona State University in the 1990s. The numerical method is verified by simulating the excitation of steady crossflow vortices through micron-sized roughness as realized in the experiments. Moreover, the receptivity to free-stream vortical disturbances is investigated and it is shown that the boundary layer is most receptive, if the free-stream modes are closely aligned with the most unstable crossflow mode
QC 20101025
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Saghafi, Hamed <1984&gt. "Mechanical behavior of flat and curved laminates interleaved by electrospun nanofibers." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6598/1/Final_Thesis-revised.pdf.

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A major weakness of composite materials is that low-velocity impact, introduced accidentally during manufacture, operation or maintenance of the aircraft, may result in delaminations between the plies. Therefore, the first part of this study is focused on mechanics of curved laminates under impact. For this aim, the effect of preloading on impact response of curved composite laminates is considered. By applying the preload, the stress through the thickness and curvature of the laminates increased. The results showed that all impact parameters are varied significantly. For understanding the contribution rate of preloading and pre-stress on the obtained results another test is designed. The interesting phenomenon is that the preloading can decrease the damaged area when the curvature of the both specimens is the same. Finally the effect of curvature type, concave and convex, is investigated under impact loading. In the second part, a new composition of nanofibrous mats are developed to improve the efficiency of curved laminates under impact loading. Therefore, at first some fracture tests are conducted to consider the effect of Nylon 6,6, PCL, and their mixture on mode I and mode II fracture toughness. For this goal, nanofibers are electrospun and interleaved between mid-plane of laminate composite to conduct mode I and mode II tests. The results shows that efficiency of Nylon 6,6 is better than PCL in mode II, while the effect of PCL on fracture toughness of mode I is more. By mixing these nanofibers the shortage of the individual nanofibers is compensated and so the Nylon 6,6/PCL nanofibers could increased mode I and II fracture toughness. Then all these nanofibers are used between all layers of composite layers to investigate their effect on damaged area. The results showed that PCL could decrease the damaged area about 25% and Nylon 6,6 and mixed nanofibers about 50%.
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Books on the topic "Flat and curved panels"

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Ellis, George F. R., and George Francis Rayner Ellis. Flat and curved space-times. Oxford [England]: Clarendon Press, 1988.

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Ellis, George F. R., and George Francis Rayner Ellis. Flat and curved space-times. 2nd ed. Oxford: Oxford University Press, 2000.

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M, Williams Ruth, ed. Flat and curved space-times. Oxford: Clarendon, 1988.

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M, Williams R., ed. Flat and curved space-times. Oxford: Clarendon, 2000.

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5

United States. National Aeronautics and Space Administration, ed. Vortex sheet modeling with higher order curved panels. Ames, Iowa: Engineering Research Institute, Iowa State University, 1985.

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6

Silakoski, S. P. Matrix force analysis of flat panels. Manchester: UMIST, 1994.

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United States. National Aeronautics and Space Administration., ed. Postbuckling behavior of fiber reinforced plates and curved panels. Washington, DC: National Aeronautics and Space Administration, 1987.

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ill, Daff Russ, ed. What has a flat snout and a curved claw? Sea Girt, NJ: Dingles & Co, 2008.

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Kanner, Robert. What has a flat snout and a curved claw? Sea Girt, NJ: Dingles & Co, 2008.

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F, Knight Norman, Ambur Damodar R, and United States. National Aeronautics and Space Administration., eds. Buckling analysis of anisotropic curved panels and shells with variable curvature. [Washington, D.C: National Aeronautics and Space Administration, 1998.

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Book chapters on the topic "Flat and curved panels"

1

Abbas, Laith K., Rui Xiaoting, and Piergiovanni Marzocca. "Aerothermoelastic Behavior of Flat and Curved Panels." In Encyclopedia of Thermal Stresses, 34–53. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-007-2739-7_869.

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van Wijngaarden, Martijn. "Flat and Curved Panel Manufacturing." In Smart Intelligent Aircraft Structures (SARISTU), 645–66. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-22413-8_30.

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Perfetto, Donato, Alessandro De Luca, Giuseppe Lamanna, and Francesco Caputo. "Analysis of Guided Waves Dispersive Behavior for Damage Detection in Flat and Curved Composite Panels." In Advances on Mechanics, Design Engineering and Manufacturing IV, 503–11. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-15928-2_44.

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Sinke, J., and N. Jalving. "Curved panels." In Fibre Metal Laminates, 355–68. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0995-9_23.

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Elishakoff, Isaac. "Dramatic Effect of Cross-Correlations in Random Vibration of Point-Driven Flat Plate and Spherically Curved Panel." In Dramatic Effect of Cross-Correlations in Random Vibrations of Discrete Systems, Beams, Plates, and Shells, 201–20. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-40394-2_10.

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Stanciulescu, Ilinca, Yang Zhou, and Mihaela Nistor. "Stability Analysis of Curved Panels." In Nonlinear Dynamics, Volume 1, 259–66. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-29739-2_24.

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Moylan, Patrick. "Velocity Reciprocity in Flat and Curved Space-Time." In Springer Proceedings in Mathematics & Statistics, 403–10. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-4751-3_36.

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Kumar, Puneet, David S. Stargel, and Arun Shukla. "Response of Curved Carbon Composite Panels to Shock Loading." In Dynamic Behavior of Materials, Volume 1, 365–72. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-4238-7_47.

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Sukhanova, Olha, Oleksiy Larin, Konstantin Naumenko, and Holm Altenbach. "Dynamics of Curved Laminated Glass Composite Panels Under Impact Loading." In Advanced Structured Materials, 91–101. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-75890-5_6.

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Fallacara, Giuseppe, Maurizio Barberio, and Micaela Colella. "Topological Interlocking Blocks for Architecture: From Flat to Curved Morphologies." In Architectured Materials in Nature and Engineering, 423–45. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-11942-3_14.

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Conference papers on the topic "Flat and curved panels"

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Bisagni, Chiara, and Riccardo Vescovini. "Buckling Optimization of Stiffened Composite Flat and Curved Panels." In 52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2011. http://dx.doi.org/10.2514/6.2011-2124.

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Ambur, Damodar, Prasad Chunchu, Cheryl Rose, Paolo Feraboli, and Wade Jackson. "Scaling the Non-linear Impact Response of Flat and Curved Composite Panels." In 46th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2005. http://dx.doi.org/10.2514/6.2005-2224.

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Rabinovich, Oded, and Yeoshua Frostig. "High-Order Analysis of Unidirectional Sandwich Panels With Flat and Generally Piecewise Curved Faces and a “Soft” Core." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2037.

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Abstract The bending behavior of a unidirectional sandwich panel with flat and generally piecewise curved faces and a flexible core in the vertical direction is investigated. The studied panels consist of an upper flat face sheet, a core of a variable thickness, and a lower face sheet that can take any geometrical layout described by a piecewise analytical function. The core is assumed to be a two-dimensional elastic medium with vertical and shear rigidities only, and the faces are considered to have membrane and bending rigidities and are made of metallic or composite materials. The field equations and the boundary conditions are rigorously derived using the variational principle of virtual work. The continuity conditions between the various regions of the generally piecewise curved face are presented. Higher order effects in the form of nonlinear deformation distributions through the thickness due to flexibility of the core are incorporated in the proposed analysis. Numerical results in terms of deformations, stresses, and stress resultants are presented for some typical cases of piecewise flat-curved panels. The results demonstrate the capabilities and generality of the proposed model, especially in the ability to predict the high-order localized effects and the high stress concentrations that characterize these panels.
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LIBRESCU, L., N. CHANDIRAMANI, M. NEMETH, and J. STARNES, JR. "POSTBUCKLING OF LAMINATED FLAT AND CURVED PANELS UNDER COMBINED THERMAL AND MECHANICAL LOADINGS." In 34th Structures, Structural Dynamics and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1993. http://dx.doi.org/10.2514/6.1993-1563.

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Lin, Weiqing, and Liviu Librescu. "Thermomechanical postbuckling of shear deformable flat and curved panels on a nonlinear elastic foundation." In 37th Structure, Structural Dynamics and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1996. http://dx.doi.org/10.2514/6.1996-1466.

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Bevan, Jeffrey S., and Chuh Mei. "Piezoceramic actuator placement for structural acoustic and vibration control of flat and curved panels." In SPIE's 8th Annual International Symposium on Smart Structures and Materials, edited by L. Porter Davis. SPIE, 2001. http://dx.doi.org/10.1117/12.436577.

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Choi, Young-Tai, Ashish S. Purekar, and Norman M. Wereley. "Torque Loss and Crack Monitoring Near Fasteners for Isotropic and Composite Helicopter Tail Boom Structural Models." In ASME 2008 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2008. http://dx.doi.org/10.1115/smasis2008-531.

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Structural Health Monitoring (SHM) techniques based on high frequency wave propagation (Acousto-Ultrasonics) are of interest due to their sensitivity to incipient damage in structures. Techniques that use small, low profile transducers allow for in-situ sensing and actuation and are particularly useful for integration on aerospace structures. Additionally, signal processing and interpretation of the data becomes important in the diagnosis process. Commonly, the development of an integrated hardware and software system based on Acousto-Ultrasonics is performed on simple structures such as flat metallic panels. In this study, the curved metallic and composite panels are examined as they provide complexity in both geometry and material used to represent helicopter tail boom structures. Damage at the edges of the curved panel is investigated as these locations typically experience damage related to fatigue. Piezoelectric transducers are mounted to the structures and used to excitation and sensing of the wave modes. The data was acquired and damage indices are used to quantify the effect of two types of damage: bolt torque loss, crack propagation between two bolts.
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Wittenberg, Thomas, and Tom van Baten. "Shear Buckling Curves for Flat Stiffened Panels with Application to Glare Material." In 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2003. http://dx.doi.org/10.2514/6.2003-1955.

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Zhang, Timothy G., Lionel R. Vargas-Gonzalez, James C. Gurganus, and Sikhanda S. Satapathy. "Effects of Curvature and Architecture on Ballistic Performance of UHMWPE Helmets." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11566.

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Abstract Ballistic impact experiments were conducted on three types of Ultra-high-molecular-weight polyethylene (UHMWPE) helmets. The three types of helmets had the same geometry, but different fiber orientations in the rear layers. The test data were used to evaluate the effects of architectures. Five impact locations were chosen to understand the effects of impact locations and curvatures. The experimental data from flat and cylindrically curved UHMWPE panels were also used to compare with the helmet test data.
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Thomsen, Ole T., and Jack R. Vinson. "Comparative Study of Two Different Conceptual Design Principles for Non-Circular Pressurized Sandwich Fuselage Sections Using a High-Order Sandwich Theory Formulation." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2033.

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Abstract Results obtained as part of a design study regarding a non-circular pressurized sandwich fuselage section are presented. The originating problem is associated with preliminary studies for the “Global Range Transport” envisaged by the “New World Vistas” program of the United States Air Force. The modeling and analysis is conducted using a high-order sandwich theory formulation in which the elastic response of each face laminate is accounted for, including bending-stretching coupling and transverse shear deformations, and where the transverse flexibility of the core is included. The sandwich fuselage envisaged may contain flat, tapered and curved sandwich elements, and a high-order sandwich theory formulation is developed to analyze each of these configurations. The paper includes a brief presentation of the adopted high-order sandwich theory with special emphasis on the application for the analysis of sandwich panels with variable core thickness, and for the analysis of curved sandwich panels. Numerical results obtained for two different mid-plane asymmetric fuselage sections are presented and compared; one with constant core thickness, and one with varying core thickness.
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Reports on the topic "Flat and curved panels"

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Zaldivar, R. J., and R. Casteneda. Cure Evaluation of Two Critical Composite Hybrid Flat Panels for use in a High-Dimensional Stability Satellite Application. Fort Belvoir, VA: Defense Technical Information Center, July 2003. http://dx.doi.org/10.21236/ada418488.

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Croop, Harold C. Fabrication of Curved Graphite/Epoxy Compression Test Panels and Generation of Material Properties. Fort Belvoir, VA: Defense Technical Information Center, October 1985. http://dx.doi.org/10.21236/ada368444.

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