Artículos de revistas: "Flat and curved panels"

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Szelag, Agata, Tadeusz Kamisiński, Mirosława Lewińska, Jarosław Rubacha y Adam Pilch. "The Characteristic of Sound Reflections from Curved Reflective Panels". Archives of Acoustics 39, n.º 4 (1 de marzo de 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. y A. V. ASHA. "PARAMETRIC RESONANCE CHARACTERISTICS OF ANGLE-PLY TWISTED CURVED PANELS". International Journal of Structural Stability and Dynamics 08, n.º 01 (marzo de 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. y S. Parthan. "Axial Wave Propagation in Infinitely Long Periodic Curved Panels". Journal of Vibration and Acoustics 125, n.º 1 (1 de enero de 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 y Zhichun Yang. "Nonlinear Flutter Response of Heated Curved Composite Panels with Embedded Macrofiber Composite Actuators". Advances in Materials Science and Engineering 2018 (26 de diciembre de 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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5

Zhang, Y. y F. L. Matthews. "Large Deflection Behavior of Simply Supported Laminated Panels Under In-Plane Loading". Journal of Applied Mechanics 52, n.º 3 (1 de septiembre de 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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6

Bates, Trent P., Ian C. Bacon, Scott D. Sommerfeldt y 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, n.º 4 (octubre de 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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7

Yurddaskal, Melis y Buket Okutan Baba. "Experimental and numerical analysis of vibration frequency in sandwich composites with different radii of curvature". Journal of Sandwich Structures & Materials 21, n.º 8 (29 de agosto de 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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8

Bartha, Michael C., Paul Allie y 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, n.º 1 (diciembre de 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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9

Pirzada, Luqman Ahmed, Xiaoli Wu ., Qaiser Ali y Asif Khateeb . "Investigation of Performance of Solar Flat and Curved Plate Collectors through Numerical Simulations". January 2021 40, n.º 1 (1 de enero de 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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10

De Luca, Alessandro, Donato Perfetto, Antonio Polverino, Antonio Aversano y Francesco Caputo. "Finite Element Modeling Approaches, Experimentally Assessed, for the Simulation of Guided Wave Propagation in Composites". Sustainability 14, n.º 11 (6 de junio de 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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11

Vescovini, Riccardo y Chiara Bisagni. "Buckling Analysis and Optimization of Stiffened Composite Flat and Curved Panels". AIAA Journal 50, n.º 4 (abril de 2012): 904–15. http://dx.doi.org/10.2514/1.j051356.

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12

L. Librescu, M. P. Nemeth, J. H. St. "NONLINEAR RESPONSE OF FLAT AND CURVED PANELS SUBJECTED TO THERMOMECHANICAL LOADS". Journal of Thermal Stresses 23, n.º 6 (agosto de 2000): 549–82. http://dx.doi.org/10.1080/01495730050143134.

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13

Jiang, Ziyi, Wei Li, Xiumei Liu, Fan Jiang y Beibei Li. "Research on different venting performance between flat and curved bursting panels". Journal of Loss Prevention in the Process Industries 65 (mayo de 2020): 104134. http://dx.doi.org/10.1016/j.jlp.2020.104134.

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14

Featherston, C. A. y C. Ruiz. "Buckling of curved panels under combined shear and compression". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 212, n.º 3 (1 de marzo de 1998): 183–96. http://dx.doi.org/10.1243/0954406981521141.

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The analytical work which has been carried out to determine the buckling load and post-buckling behaviour of curved panels under various types of loading and different boundary conditions is not as comprehensive as that for flat plates. Only elementary loading and boundary conditions have been analysed. In addition to this, many of the theories developed have not been tested experimentally. This paper outlines a series of tests carried out to determine the accuracy of the theoretical buckling loads. The experimental results are then used to examine whether or not finite element analysis can be used as an alternative to determine collapse loads and post-buckling behaviour, especially in cases where no theoretical solutions exist.

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15

Chang, M. Y. y L. Librescu. "Postbuckling of shear-deformable flat and curved panels under combined loading conditions". International Journal of Mechanical Sciences 37, n.º 2 (febrero de 1995): 121–43. http://dx.doi.org/10.1016/0020-7403(94)e0000-9.

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16

Hohe, Jörg, Liviu Librescu y Sang Yong Oh. "Dynamic buckling of flat and curved sandwich panels with transversely compressible core". Composite Structures 74, n.º 1 (julio de 2006): 10–24. http://dx.doi.org/10.1016/j.compstruct.2005.03.003.

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17

Narita, Daisuke y Yoshihiro Narita. "Analysis and Design of Curved Laminated Composite Panels under External Pressure". Key Engineering Materials 353-358 (septiembre de 2007): 1271–74. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.1271.

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Curved panels can bear more lateral load than flat plates because they can transmit the external load along curved surface in addition to load-carrying capacity by the bending stiffness. For curved panels, however, there is a critical point of the lateral load that structure can endure before it buckles. On the other hand, composites are known to have more advantages in specific strength and stiffness than conventional metal materials. The present paper proposes a semi-analytical method to predict the initial buckling loads of slightly curved panels composed of thin orthotropic composite layers under general boundary conditions. Based on the Donnell type theory, the potential strain energy is evaluated as a sum of stretching energy, stretching-bending coupling energy and bending energy, and the external work done by uniform external pressure is included in the functional. The eigenvalue equation is derived by the Ritz method to yield such initial buckling load parameters as eigenvalues. Numerical examples include a list of buckling loads and the corresponding buckling patterns for typical panels with simply supported and clamped edges.

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18

Hause, Terry, Liviu Librescu y Charles J. Camarda. "Postbuckling of anisotropic flat and doubly-curved sandwich panels under complex loading conditions". International Journal of Solids and Structures 35, n.º 23 (agosto de 1998): 3007–27. http://dx.doi.org/10.1016/s0020-7683(97)00360-0.

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19

Pradhan, Suman, Mostafa Mohammadabadi, Edward Entsminger, Kevin Ragon, Laya Khademibami y Jason Street. "Development of a high-performance building material using wood-based corrugated panels manufactured via cold-forming technique". BioResources 18, n.º 3 (18 de mayo de 2023): 4666–75. http://dx.doi.org/10.15376/biores.18.3.4666-4675.

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A wood-based sandwich panel with a corrugated core was developed as a building material. A matched-die mold manufactured from commercial plywood was used to fabricate the corrugated panels through a cold-forming process. A cold-setting resin was applied on southern yellow pine (Pinus spp.) veneers with an average thickness of 4 mm, and four plies of them were formed into a corrugated geometry using a wooden mold. When the resin was cured, the corrugated panel of veneers retained the corrugated shape after load removal. Facesheets of the sandwich structures were fabricated using three plies of the same veneers. To evaluate the effect of this corrugated geometry on the structural performance, the same veneers — regarding number, thickness, and orientation — used for the sandwich panel were adopted to fabricate laminated flat panels. Both sandwich and laminated flat panels were submitted to a four-point bending test. The results confirmed the sandwich effect, i.e. a 1741% increase in the bending stiffness of sandwich panels compared to that of laminated flat panels. Sandwich panels developed in this study were compared to Structural Insulated Panels (SIPs), wood-framed structures known as stud walls, and sandwich panels produced using a hot-pressing technique. The cold-formed sandwich panels had higher structural performance than commercial building materials.

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20

Watts, Gaurav, M. K. Singha y S. Pradyumna. "A numerical study on the nonlinear behavior of corner supported flat and curved panels". Archive of Applied Mechanics 88, n.º 4 (17 de noviembre de 2017): 503–16. http://dx.doi.org/10.1007/s00419-017-1322-1.

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21

A R, Sreadha y Chitaranjan Pany. "Static, Free Vibration and Buckling Analysis of Composite Panels; A Review". Advanced Journal of Graduate Research 9, n.º 1 (27 de noviembre de 2020): 21–45. http://dx.doi.org/10.21467/ajgr.9.1.21-45.

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A composite material is generally a combination of materials differing in composition or form on a macro scale for the purposes of attaining specific characteristics and properties. The developments in the field of composite materials have granted significant weight reduction in structural design. When compared to metallic materials, composites offer many advantages, especially high strength, stiffness to weight ratio, excellent fatigue properties, and corrosion resistance. Plates, curved panels, the cylindrical shell-shaped forms of models are being broadly used in many structural packages of engineering structure. For design the structure, it is important to know the behaviour of these under static, free vibration, buckling condition. The present paper aims to review the literature on static, free vibration, and buckling analysis of composite flat panel, curved panel, and cylindrical shell. Further, the testing procedure of laminate, design guidelines of laminates and cost estimations with mechanical properties comparison of laminate with metal, CLT (classical lamination theory) basis including thermal and moisture expansion for stiffness evaluation are also summarised in this paper.

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22

Lee, Chankyu, Sangyun Shin y Raja Raymond Issa. "Rationalization of Free-Form Architecture Using Generative and Parametric Designs". Buildings 13, n.º 5 (10 de mayo de 2023): 1250. http://dx.doi.org/10.3390/buildings13051250.

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Free-form architecture is a prominent trend in contemporary architecture where streamlined geometric buildings are constructed. The main problem in free-form architecture is rationalization, which involves realizing free-form surfaces at a reasonable cost while meeting design requirements. Balancing the design intents and construction costs simultaneously is essential for successful rationalization. This study proposes parametric and generative program flows to balance both requirements efficiently. The suggested parametric program flow, which is based on a mathematical algorithm, classifies a free-form surface into multiple areas, which are favorable to flat, single-curved, and double-curved panels. The proposed generative program flow optimizes the double-curved panels’ area through the integration of Multi-Objective Optimization and Pareto optimality. Designers can select the best design option that fits their design objectives through trade-offs using the results of the program flows. Eventually, more efficient and mindful decisions can be made in the early design process by using the results of this study for successful free-form architecture.

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23

Badi, Nacer, Azemtsop Manfo Theodore, Saleh A. Alghamdi, Ayshah S. Alatawi, Adnan Almasoudi, Abderrahim Lakhouit, Aashis S. Roy y Alex Ignatiev. "Thermal effect on curved photovoltaic panels: Model validation and application in the Tabuk region". PLOS ONE 17, n.º 11 (2 de noviembre de 2022): e0275467. http://dx.doi.org/10.1371/journal.pone.0275467.

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This paper aimed to investigate the temperature effect on photovoltaic (PV) cell parameters. The PV cell parameters such as series and parallel resistances, diode ideality factor, and diode saturation current, are not considered in the reported stepwise modeling. The present work aims to improve available models used in the modeling and simulation of PV modules to support the researcher and power project developer. All the required temperature-dependent parameters are determined to model the simulated PV module with high accuracy using Simulink/MATLAB software. To validate the method, a 36-cell-50W solar panel with different radii of curvature is set up to assess solar power outputs under varying irradiance and temperature conditions. For the present application, the Tabuk region (Saudi Arabia) is chosen based on its location and climatic conditions. The method provided conformity to the measured power outputs for varying Global Horizontal Irradiance (GHI) and temperature conditions. The maximum power output of the PV module increases from 14.4 W to 25.8 W when the received solar power density varies from 307 W/m2 to 526 W/m2 depending on the level of curvature starting from a semi-cylindrical shape to a vaulted shape to a flat shape. The curved PV module shows slightly higher power variation with temperature as compared to the flat one. Above 25°C, the power output is about 20% less at a maximum temperature of 65°C. When the temperature drops below 25°C, the power outputs increase about 6% and 11.5% for corresponding temperatures of 15°C and 5°C, respectively.

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Librescu, L., W. Lin, M. P. Nemeth y J. H. Starnes. "THERMOMECHANICAL POSTBUCKLING OF GEOMETRICALLY IMPERFECT FLAT AND CURVED PANELS TAKING INTO ACCOUNT TANGENTIAL EDGE CONSTRAINTS". Journal of Thermal Stresses 18, n.º 4 (julio de 1995): 465–82. http://dx.doi.org/10.1080/01495739508946314.

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Esmaeili Shayan, Mostafa, Gholamhassan Najafi, Barat Ghobadian, Shiva Gorjian, Mohamed Mazlan, Mehdi Samami y Alireza Shabanzadeh. "Flexible Photovoltaic System on Non-Conventional Surfaces: A Techno-Economic Analysis". Sustainability 14, n.º 6 (18 de marzo de 2022): 3566. http://dx.doi.org/10.3390/su14063566.

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Renewable energy policies emphasize both the utilization of renewable energy sources and the improvement of energy efficiency. Over the past decade, built-in photovoltaic (BIPV) technologies have mostly focused on using photovoltaic ideas and have been shown to aid buildings that partially meet their load as sustainable solar energy generating technologies. It is challenging to install conventional photovoltaic systems on curved facades. In this research, elastic solar panels assisted by flexible photovoltaic systems (FPVs) were developed, fabricated, and analyzed on a 1 m2 scale. A flexible structure on a flat, hemispherical, and cylindrical substrate was studied in real terms. Using the LabVIEW application, warm and dry climate data has been recognized and transmitted online. The results showed that when installed on the silo and biogas interfaces, the fill factor was 88% and 84%, respectively. Annual energy production on the flat surface was 810 kWh, on the cylindrical surface was 960 kWh, and on the hemisphere surface was 1000 kWh, respectively. The economic results indicate that the net present value (NPV) at a flat surface is USD 697.52, with an internal rate of return (IRR) of 34.81% and a capital return term of 8.58 years. Cylindrical surfaces and hemispheres each see an increase of USD 955.18. The investment yield returned 39.29% and 40.47% for cylindrical and hemispheres structures. A 20% increase in fixed investment in the flat system increased IRR by 21.3%, while this increase was 25.59% in the cylindrical system and 24.58% in the hemisphere. Research innovation is filling the gap on the use of flexible solar panels on curved and unconventional surfaces.

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McIntyre, Finn, Mathieu Sellier, Shayne Gooch, Volker Nock y Nigel Sharplin. "APPLICATIONS OF ROTATIONAL MANIPULATORS IN THE MANUFACTURE AND CHARACTERIZATION OF HIGHLY CURVED THIN FILMS". Proceedings of the Design Society 3 (19 de junio de 2023): 623–32. http://dx.doi.org/10.1017/pds.2023.63.

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AbstractWhat do common devices such as smartphones, CD’s and solar panels all have in common? They are all examples of innovative technology that is still limited to flat, rigid geometries. This is primarily due to the limitations of the manufacturing processes used to create components within these devices, key among them the thin polymer films produced through spin coating.Spin coating is a technique used due to its ability to effectively create uniform films on the scale of micro or nanometres. However, it relies on a planar substrate to produce uniform layers, thus restricting the design of components manufactured using this process to simple, flat objects. As the requirement for curved device geometries expands, complex alternative fabrication methods are being implemented in industry.For spin coating to remain relevant, a viable process for controlling the fluid flow over curved surfaces must be developed. This research investigates the hypothesis that coating distributions can be controlled through optimized rotation of a curved substrate. Where a multi-axis rotational manipulator and novel characterization system have been developed to investigate the fabrication of curved devices using the improved spin coating technique.

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Iseki, H., R. Sowerby, D. Bhattacharyya y P. Gatt. "A Theoretical and Experimental Study of a Curved Strip Compressed by a Flat Plate". Journal of Applied Mechanics 56, n.º 1 (1 de marzo de 1989): 96–104. http://dx.doi.org/10.1115/1.3176072.

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The quasi-static loading of a curved strip compressed by a flat, rigid plate is considered, with particular reference to large deformations and the ensuing buckling behavior. Experiments were performed on curved strips of constant width but of different thickness. The strips were initially deformed to a fixed radius of curvature and stress relieved before pinning the ends. The span was held constant at about 305 mm. The deformation characteristics have been analyzed using an incremental finite element technique. Particular attention has been paid to modeling the situation when a node contacts the plate and the condition for separation of the strip from the plate. The predicted loads and deformation modes agreed well with experimental results from tests on steel and aluminum specimens. The experimental and theoretical procedures are pertinent to the study of dent resistance of sheet metal stampings, particularly automotive panels.

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28

Lin, Weiqing y Liviu Librescu. "THERMOMECHANICAL POSTBUCKLING OF GEOMETRICALLY IMPERFECT SHEAR–DEFORMABLE FLAT AND CURVED PANELS ON A NONLINEAR ELASTIC FOUNDATION". International Journal of Engineering Science 36, n.º 2 (enero de 1998): 189–206. http://dx.doi.org/10.1016/s0020-7225(97)00055-4.

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Librescu, Liviu y Weiqing Lin. "Postbuckling and vibration of shear deformable flat and curved panels on a non-linear elastic foundation". International Journal of Non-Linear Mechanics 32, n.º 2 (marzo de 1997): 211–25. http://dx.doi.org/10.1016/s0020-7462(96)00057-1.

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30

Friedman, R., J. Kennedy y D. Royster. "Analysis and Compression Testing of 2024 and 8009 Aluminum Alloy Zee-Stiffened Panels". Journal of Engineering Materials and Technology 116, n.º 2 (1 de abril de 1994): 238–43. http://dx.doi.org/10.1115/1.2904279.

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Zee-stiffened compression test panels, fabricated with dispersion-strengthened, high-temperature 8009 aluminum alloy sheet, were evaluated to determine the alloy’s feasibility for compression-critical applications. A compression panel design configuration was obtained using a strength analysis program that predicts the post-skin buckling strength of flat or curved-skinned, metallic-stiffened structure. Three short-column panels were tested to failure at room temperature: (a) a baseline riveted panel fabricated with 2024-T62 aluminum zee stringers and a 2024-T81 aluminum skin, (b) a riveted panel fabricated with 8009 aluminum zee stringers and skin, and (c) a resistance spot-welded panel fabricated with 8009 aluminum zee stringers and skin. The 8009 alloy exhibited pronounced, compressive strength anisotropy, necessitating panel orientation to take advantage of the higher compressive yield in the sheet transverse direction. Compression test results were in good agreement with the predicted compression allowables since they were within 5 percent of the test strength. The 8009 aluminum riveted panel exhibited superior skin buckling resistance and failed in the wrinkling mode, as predicted, at a load approximately 15 percent higher than that of the baseline 2024 panel. The spotwelded 8009 panel did not fail in the wrinkling mode since the spot welds failed in tension shortly after the skin locally buckled. The latter test indicates that the spot welded skin-stringer combinations should not be used above the buckling stress. Due to its excellent microstructural stability at elevated temperatures, high-temperature compression panels of 8009 alloy offer potential weight savings of 25 percent compared with conventional aluminum alloys.

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31

Rabinovitch, O. y Y. Frostig. "High-Order Analysis of Unidirectional Sandwich Panels with Flat and Generally Curved Faces and a “Soft” Core". Journal of Sandwich Structures & Materials 3, n.º 2 (abril de 2001): 89–116. http://dx.doi.org/10.1106/4wab-ndgk-lxb2-5avh.

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32

Librescu, Liviu y Weiqing Lin. "Vibration of thermomechanically loaded flat and curved panels taking into account geometric imperfections and tangential edge restraints". International Journal of Solids and Structures 34, n.º 17 (junio de 1997): 2161–81. http://dx.doi.org/10.1016/s0020-7683(96)00025-x.

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33

Kumar, S. Suresh, H. Ashwin Clement y R. Karthik. "Mixed mode fracture analysis of multiple cracks in flat and curved stiffened panels of aircraft fuselage structures". Archive of Applied Mechanics 87, n.º 11 (17 de agosto de 2017): 1815–28. http://dx.doi.org/10.1007/s00419-017-1289-y.

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34

Běhal, Jiří y Pavel Zděnek. "Dynamic behaviour of composite panels under acoustic loading". International Journal of Structural Integrity 11, n.º 5 (19 de noviembre de 2019): 710–22. http://dx.doi.org/10.1108/ijsi-10-2018-0066.

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Purpose There are structural elements on the aircraft that may be exposed to high-intensity sound levels. One of them is an air inlet duct of the jet engine. To prepare data for the air duct damage tolerance analysis, flat panels were tested under acoustic loading. The paper aims to discuss this issue. Design/methodology/approach The acoustic fatigue test equipment for grazing wave’s incidence was designed based on the FE analyses. Flat composite panels were designed and manufactured using the Hexply 8552/AGP193-PW prepreg with the simulation of production imperfections or operational damage. The dynamic behaviour of panels has been tested using three regimes of acoustic loading: white noise spectrum, engine noise spectrum and discrete harmonic frequencies. The panel deflection was monitored along its longitudinal axis, and the ultrasonic NDT instruments were used for the monitoring of relevant delamination increments. The FE model of the panel was created in Abaqus to study panel dynamic characteristics. Findings No delamination progress was observed by NDT testing even if dynamic characteristics, especially modal frequency, of the panel changed during the fatigue test. Rayleigh damping coefficients were evaluated for their use in FE models. Significant differences were found between the measured and computed panel deflection curves near the edge of the panel. Originality/value The research results underscored the signification of the FE model boundary conditions and the element type selections when the panel works like a membrane rather than a plate because of their low bending stiffness.

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35

Chang, De Gong, Song Mei Li, Dong Hao Liu, Zhen Zhong Fei y Xin Jun Gao. "Finite Element Analysis on Protective Airtight Doors of Mine Removable Rescue Capsule". Applied Mechanics and Materials 341-342 (julio de 2013): 511–14. http://dx.doi.org/10.4028/www.scientific.net/amm.341-342.511.

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In this paper, a cured door structure of mine rescue capsule is proposed, and compared with ordinary flat panel doors. Firstly two kind of three-dimensional solid models of mine removable protective airtight doors are established by the Pro/e software. And then take the advantage of the strength analysis of ANSYS finite element software to draw the stress and strain diagrams. The analysis results show that the strength and stiffness of the curved door is better than ordinary flat panel doors, which provide important theoretical basis and reference value on the design, research and dynamic analysis of the life-saving door.

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36

Mohammadi, Aidin, Alireza Pachenari y Behnam Sadeghi. "Numerical Study on the Behavior and Bearing Mechanism of Flat Slabs in Column Loss Events". Advances in Civil Engineering 2021 (6 de febrero de 2021): 1–12. http://dx.doi.org/10.1155/2021/8834638.

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This study investigates the behavior and the load-bearing mechanism of a typical flat slab with rectangular panels in several scenarios including the removal of a corner, penultimate, and internal columns. The scenarios are rather similar to those used in the conventional evaluation of the progressive collapse potential; however, application of the uniformly distributed loading over panels adjacent to the removed columns was not limited to twice the value of the initial load. Thus, load-deflection curves were drawn up to the point in which a great number of longitudinal slab bars ruptured. Introducing 5 stages on each curve, finite element outputs on concrete cracking pattern and rebar stress state were presented. A significant increase in the stresses along the diagonals of the slab panels accompanied by bar ruptures around columns adjacent to the removed column proved contribution of an important load-bearing mechanism in addition to the behavior called “quasiframe action.” Consecutive rupture of bars showed formation of a zipper-type collapse mode as well as a great tendency to transfer load share of missing column mainly along shorter direction of slab panels. Moreover, the findings indicated that the slab damaged zone could exceed the panels under uniform overloading.

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37

Kong, Jackson. "On the Validity of Flat-Plate Finite Strip Approximation of Circular Cylindrical Shells". Journal of Computational Engineering 2014 (11 de febrero de 2014): 1–13. http://dx.doi.org/10.1155/2014/543794.

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The validity of modeling curved shell panels using flat-plate finite strips has been demonstrated in the past by comparing finite strip numerical results with analytical solutions of a few benchmark problems; to date, no mathematical exact solutions of the method or its explicit forms of error terms have been rigorously derived to demonstrate analytically its validity. Using a unitary transformation approach (abbreviated as the U-transformation herein), an attempt is made in this paper to derive mathematical exact solutions of flat-plate finite strips in cylindrical shell vibration analysis. Unlike the conventional finite strip method which involves assembly of the global system of matrix equation and its numerical solution, the U-transformation method makes use of the inherent cyclic symmetry of cylindrical shells to decouple the global matrix equation into one involving only a few unknowns, thus rendering explicit form of solutions for the flat-shell finite strip to be derived. Such explicit solutions can be subsequently expanded into Taylor's series whose results reveal directly their convergence to the exact solutions and the corresponding rate of convergence.

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38

Hosseini, M., S. M. R. Khalili y K. Malekzadeh Fard. "An indentation law for doubly curved composite sandwich panels with rigid-plastic core subjected to flat-ended cylindrical indenters". Composite Structures 105 (noviembre de 2013): 82–89. http://dx.doi.org/10.1016/j.compstruct.2013.04.032.

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39

Muc, Aleksander, Małgorzata Chwał y Adam Stawiarski. "Experimental and numerical analysis of heat convection in cylindrical composite structures with internal defects". Advanced Composites Letters 28 (1 de enero de 2019): 096369351987969. http://dx.doi.org/10.1177/0963693519879699.

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The present article discusses the influence of delamination and external loads on the heat transfer in flat and curved laminated panels. Three cases are considered in details: (1) the unloaded structure (length is a constant), (2) the static loading, and (3) the fatigue loading. Here, the comparison between experimental and numerical (finite element method) results is presented. The numerical model allows us to adopt implementations of various boundary conditions as well as the size of delamination. The influence of the shallowness parameter and the thermal resistance is demonstrated. The experimental detection of temperature contours during the cooling process has been conducted at different points in the area surrounding the delamination.

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40

Marucci, Alvaro, Danilo Monarca, Andrea Colantoni, Enio Campiglia y Andrea Cappuccini. "Analysis of the internal shading in a photovoltaic greenhouse tunnel". Journal of Agricultural Engineering 48, n.º 3 (14 de septiembre de 2017): 154. http://dx.doi.org/10.4081/jae.2017.622.

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In recent years, the increasing interest in energy production from renewable energy sources has led to photovoltaic elements being placed on greenhouse coverings. The shading of crops by these elements can, however, cause problems regarding the normal course of agricultural activity. All studies thus far on the application of photovoltaic (PV) panels as a greenhouse covering material have focused on flat roof structures. Tunnel greenhouses, due to their curved shape, do not lend themselves easily to accommodating PV panels on even part of the cover. In this study, we analysed the shading variation inside a tunnel greenhouse that was produced by applying flexible and transparent PV panels in a checkerboard arrangement. The transparent flexible PV panels are manufactured using monocrystalline silicon cells, with an efficiency of 18%, incorporated into polymers with high resistance. The PV panel dimensions are 1.116×0.165 m. The simulation software Autodesk® Autocad2010® was used for this study. The variation and distribution of the shading percentage of PV panels were analysed in relation to the surface area affected by the photovoltaic roof, the total area of the greenhouse and the section of the greenhouse. In particular, we studied the variations in the percentage of shading and the size of the shaded area on the twenty-first day of each month of the year. The results show some regularity in the shading percentage, mainly due to the curvilinear shape of the section of the greenhouse. From mid-March to mid- September, the shading in the middle of the day is almost always inside the greenhouse. In the other months of the year, it is partly inside and partly outside the tunnel greenhouse. With the photovoltaic arrangement adopted, the percentage of shading during the year never exceeds 40%.

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41

Yang, Zhi Chun y Wei Xia. "Instability of Heated Panels in Supersonic Air Flow". Advanced Materials Research 33-37 (marzo de 2008): 1101–8. http://dx.doi.org/10.4028/www.scientific.net/amr.33-37.1101.

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An investigation on the stability of heated panels in supersonic airflow is performed. The nonlinear aeroelastic model for a two-dimensional panel is established using Galerkin method and the thermal effect on the panel stiffness is also considered. The quasi-steady piston theory is employed to calculate the aerodynamic load on the panel. The static and dynamic stabilities for flat panels are studied using Lyapunov indirect method and the stability boundary curve is obtained. The static deformation of a post-buckled panel is then calculated and the local stability of the post-buckling equilibrium is analyzed. The limit cycle oscillation of the post-buckled panel is simulated in time domain. The results show that a two-mode model is suitable for panel static stability analysis and static deformation calculation; but more than four modes are required for dynamic stability analysis. The effects of temperature elevation and dimensionless parameters related to panel length/thickness ratio, material density and Mach number on the stability of heated panel are studied. It is found that panel flutter may occur at relatively low aerodynamic pressure when several stable equilibria exist for the aeroelastic system of heated panel.

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42

Yankovskii, A. P. "The Refined Model of the Elastic-Plastic Dynamic Behavior of Reinforced Curved Panels Sensitive to Strain Rate". PNRPU Mechanics Bulletin, n.º 2 (15 de diciembre de 2021): 191–202. http://dx.doi.org/10.15593/perm.mech/2021.2.17.

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The initial-boundary value problem of dynamic elastic-viscoplastic deformation of flexible curved panels (shallow shells) with plane -cross and spatial reinforcement structures is formulated. The inelastic behavior of the materials of the composition components is described by the constitutive equations of the theory of plastic flow with isotropic hardening, and their sensitivity to strain rate is taken into account. The geometric nonlinearity of the problem is taken into account in the Karman approximation. The used kinematic and dynamic two-dimensional relations and the corresponding boundary conditions make it possible to describe, with varying degrees of accuracy, the mechanical bending behavior of shallow composite shells. This takes into account the possible weak resistance of such reinforced panels to transverse shears. In the first approximation, the used two-dimensional equations, the initial and boundary conditions degenerate into the relations of the traditional non-classical Ambartsumyan theory. For the numerical integration of the formulated nonlinear dynamic problem, an algorithm of time steps is applied, based on the use of an explicit scheme of the cross type. The elastoplastic and elastic-viscoplastic behavior of the reinforced cylindrical shallow shells under transverse dynamic loads generated by an air blast wave is investigated. Metal-composite and fiberglass thin-walled constructions are considered. It is shown that the refusal to take into account the dependence of the plastic properties of the components of the composition on the rate of their deformation does not allow adequately describing the inelastic dynamic behavior of both metal-composite and fiberglass shallow shells. It is shown that in the calculations of even relatively thin reinforced cylindrical panels (with a relative thickness of 1/50), the use of the Ambartsumyan theory leads to completely unacceptable results in comparison with the refined bending theory. It has been demonstrated that even for relatively thin curved fiberglass panels, replacing the traditional flat -cross reinforcement structure with a spatial structure with obliquely laid fiber families can significantly reduce not only the intensity of deformations in the binder, but also the maximum deflection values in modulus. For metal-composite shallow shells with a weakly expressed anisotropy of the composition, the positive effect of the indicated replacement of reinforcement structures is practically not manifested.

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43

De Maio, Davide, Carmine D’Alessandro, Antonio Caldarelli, Daniela De Luca, Emiliano Di Gennaro, Roberto Russo y Marilena Musto. "A Selective Solar Absorber for Unconcentrated Solar Thermal Panels". Energies 14, n.º 4 (9 de febrero de 2021): 900. http://dx.doi.org/10.3390/en14040900.

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A new Selective Solar Absorber, designed to improve the Sun-to-thermal conversion efficiency at mid temperatures in high vacuum flat thermal collectors, is presented. Efficiency has been evaluated by using analytical formulas and a numerical thermal model. Both results have been experimentally validated using a commercial absorber in a custom experimental set-up. The optimization procedure aimed at obtaining Selective Solar Absorber is presented and discussed in the case of a metal dielectric multilayer based on Cr2O3 and Ti. The importance of adopting a real spectral emissivity curve to estimate high thermal efficiency at high temperatures in a selective solar absorber is outlined. Optimized absorber multilayers can be 10% more efficient than the commercial alternative at 250 °C operating temperatures, reaching 400 °C stagnation temperature without Sun concentration confirming that high vacuum flat thermal collectors can give important contribution to the energy transition from fossil fuels to renewable energy for efficient heat production.

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44

Bacon, Ian C., Gibson H. Campbell, John C. Ebeling, Scott D. Sommerfeldt y Jonathan D. Blotter. "Determination of radiated sound power from acoustic sources using the VBSP method and a transparent acoustic boundary". Journal of the Acoustical Society of America 151, n.º 4 (abril de 2022): A227. http://dx.doi.org/10.1121/10.0011144.

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Significant progress has been made to develop a vibration-based sound power (VBSP) method as an alternative means to determine the radiated acoustic energy from structures. This method has been validated for flat plates, cylindrical-shells, simple curved plates, and arbitrarily curved panels. However, many acoustic sources, such as a blender or motor, have sound power contributions that are enclosed within the structure and therefore cannot be scanned properly using a vibrometer. A rigid enclosure with a single mylar face for one side of the enclosure was fabricated to enclose the acoustic source, such as an “acoustic tent” around the structure of interest, so that the VBSP method could be applied to and obtain the radiated sound power. Due to the nature of the sources, this application of the VBSP method will have limitations that are not present in the aforementioned work. A calibration curve was developed to account for the effects that the tent had on the sources used for testing and used to correct the experimental VBSP sound power measurements from the acoustic tent. Results will be shown comparing the sound power obtained from the VBSP method with the sound power of the source in a reverberation chamber using ISO 3741. Funding for this work was provided by the National Science Foundation (NSF). [Funding for this work was provided by the National Science Foundation (NSF).]

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45

Esmaeili Shayan, Mostafa, Gholamhassan Najafi, Barat Ghobadian, Shiva Gorjian y Mohamed Mazlan. "Sustainable Design of a Near-Zero-Emissions Building Assisted by a Smart Hybrid Renewable Microgrid". International Journal of Renewable Energy Development 11, n.º 2 (15 de febrero de 2022): 471–80. http://dx.doi.org/10.14710/ijred.2022.43838.

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Renewable energy regulations place a premium on both the use of renewable energy sources and energy efficiency improvements. One of the growing milestones in building construction is the invention of green cottages. Building Integrated Photovoltaic (BIPV) technologies have been proved to aid buildings that partially meet their energy demand as sustainable solar energy generating technologies throughout the previous decade. Curved facades provide a challenge for typical photovoltaics. This study designed, produced, and assessed elastic solar panels supported by flexible photovoltaic systems (FPVS) on a 1 m2 layer. The LabVIEW program recognizes and transmits online data on warm and dry climates. The fill factor was 88% and 84%, respectively, when installed on the silo and biogas surfaces. The annual energy output was 810 kWh on a flat surface, 960 kWh on a cylindrical surface, and 1000 kWh on a hemisphere surface. Economic analysis indicates that the NPV at Flat surface is $ 697.52, with an IRR of 34.81% and an 8.5-year capital return period. Cylindrical surfaces and hemispheres both get a $ 955.18 increase. For cylindrical and hemispheric buildings, the investment yield was 39.29% and 40.47%, respectively. A 20% increase in fixed investment boosted the IRR by 21.3% in the flat system. While the cylindrical system had a 25.59% raise, the hemisphere saw a 24.58% gain

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46

Featherston, C. A. "The use of finite element analysis in the examination of instability in flat plates and curved panels under compression and shear". International Journal of Non-Linear Mechanics 35, n.º 3 (mayo de 2000): 515–29. http://dx.doi.org/10.1016/s0020-7462(99)00038-4.

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47

Franco-Urquiza, Edgar Adrián, Annika Dollinger, Mauricio Torres-Arellano, Saúl Piedra, Perla Itzel Alcántara Llanas, Victoria Rentería-Rodríguez y Cecilia Zarate Pérez. "Innovation in Aircraft Cabin Interior Panels Part I: Technical Assessment on Replacing the Honeycomb with Structural Foams and Evaluation of Optimal Curing of Prepreg Fiberglass". Polymers 13, n.º 19 (22 de septiembre de 2021): 3207. http://dx.doi.org/10.3390/polym13193207.

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Sandwich composites are widely used in the manufacture of aircraft cabin interior panels for commercial aircraft, mainly due to the light weight of the composites and their high strength-to-weight ratio. Panels are used for floors, ceilings, kitchen walls, cabinets, seats, and cabin dividers. The honeycomb core of the panels is a very light structure that provides high rigidity, which is considerably increased with fiberglass face sheets. The panels are manufactured using the compression molding process, where the honeycomb core is crushed up to the desired thickness. The crushed core breaks fiberglass face sheets and causes other damage, so the panel must be reworked. Some damage is associated with excessive build-up of resin in localized areas, incomplete curing of the pre-impregnated fiberglass during the manufacturing process, and excessive temperature or residence time during the compression molding. This work evaluates the feasibility of using rigid polyurethane foams as a substitute for the honeycomb core. The thermal and viscoelastic behavior of the cured prepreg fiberglass under different manufacturing conditions is studied. The first part of this work presents the influence of the manufacturing parameters and the feasibility of using rigid foams in manufacturing flat panels oriented to non-structural applications. The conclusion of the article describes the focus of future research.

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48

Hawkes, Elliot W., Hao Jiang y Mark R. Cutkosky. "Three-dimensional dynamic surface grasping with dry adhesion". International Journal of Robotics Research 35, n.º 8 (29 de junio de 2015): 943–58. http://dx.doi.org/10.1177/0278364915584645.

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Most robotic grasping research focuses on objects that are either not large in comparison to the gripper or have small graspable features; however, there are important applications that involve large flat or gently curved surfaces. Examples include robots that grasp the solar panels of space craft, handle large panels in manufacturing, or climb or perch on surfaces. We present a solution for grasping such surfaces consisting of groups of tiles coated with a controllable gecko-inspired adhesive. The tiles are loaded with two sets of tendons: one for distributing the forces evenly while grasping and the other for release. The gripper is passive and can attach and detach with little effort so that it does not disturb either the robot or the object to be grasped. The maximum gripping force in the normal direction can be over 1000 times greater than the required detaching force. The gripper is also fast, allowing a flying quadrotor to attach to a surface milliseconds after the tiles make contact. We present a model of the gripping mechanism and use the model to design the layout of the tiles to best support anticipated normal and tangential loads.

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49

Chand Dewangan, Hukum, Subrata Kumar Panda y Chetan Kumar Hirwani. "Numerical deflection and stress prediction of cutout borne damaged composite flat/curved panel structure". Structures 31 (junio de 2021): 660–70. http://dx.doi.org/10.1016/j.istruc.2021.02.016.

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50

Drake, K. R., S. C. Neo y A. P. Blackie. "Approximate analysis of a square flat top sandwich panel with a curved bottom skin". Composite Structures 74, n.º 3 (agosto de 2006): 354–60. http://dx.doi.org/10.1016/j.compstruct.2005.04.015.

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