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Ock, Jong-Ho. "Testing as-Built Quality of Free-Form Panels: Lessons Learned from a Case Study and Mock-up Panel Tests." Applied Sciences 11, no. 4 (February 5, 2021): 1439. http://dx.doi.org/10.3390/app11041439.
Constructing free-form buildings is very complex due to the difficulty in fabricating the curved façade. To install the façade, the complex geometric shapes of the façade need to be divided into panels. The panels developed are classified into three categories in terms of their curvatures, i.e., planar, single-curved, double-curved panels. The quality of the curved façade is determined by the geometric difference between as-built and as-designed panel shapes. Among the three types of curved panels, the double-curved panel is very difficult to form, showing greater quality discrepancy than the other two panel types. Ensuring the as-built quality of the curved façade is for contractors. The main objective of this study is to enhance small/mid-size contractors’ capacity of managing the as-built quality of the double-curved panel. To meet the study objectives, a case study of a small free-form building and empirical mock-up tests of curved panels were performed and beneficial lessons for the contractors were identified through the tests. Among diverse materials, aluminum and glass-fiber-reinforced concrete (GFRC) were utilized for the mock-up tests. Three-dimensional laser scanning technology was employed to foster the as-built data of the case study project and the mocked-up double-curved panels. The data superimposition method was used to measure the deviation between the as-designed and the as-built data of the case study.
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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.
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.
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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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.
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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Shen, Hui-Shen, Yang Xiang, and Yin Fan. "Large amplitude vibration of doubly curved FG-GRC laminated panels in thermal environments." Nanotechnology Reviews 8, no. 1 (December 31, 2019): 467–83. http://dx.doi.org/10.1515/ntrev-2019-0042.
Abstract A study on the large amplitude vibration of doubly curved graphene-reinforced composite (GRC) laminated panels is presented in this paper. A doubly curved panel is made of piece-wise GRC layers with functionally graded (FG) arrangement along the thickness direction of the panel. A GRC layer consists of polymer matrix reinforced by aligned graphene sheets. The material properties of the GRC layers are temperature dependent and can be estimated by the extended Halpin-Tsai micromechanical model. The modelling of the large amplitude vibration of the panels is based on the Reddy’s higher order shear deformation theory and the effects of the von Kármán geometric nonlinearity, the panel-foundation interaction and the temperature variation are included in the derivation of the motion equations of the panels. The solutions for the large amplitude vibration of the doubly curved FG-GRC laminated panels are obtained by applying a two-step perturbation approach. A parametric study is carried out to determine the influences of foundation stiffness, temperature variation, FG distribution pattern, in-plane boundary condition and panel curvature ratio on the natural frequencies and the nonlinear to linear frequency ratios of the doubly curved FG-GRC laminated panels.
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Wang, Chun, Xuan Ming Zhang, and Xiao Wang. "Scanning and Modeling of Large Thin-Walled Curved Surface Part." Advanced Materials Research 299-300 (July 2011): 810–15. http://dx.doi.org/10.4028/www.scientific.net/amr.299-300.810.
The large sandwich structure composed of thin-walled aluminum alloy panels, and variable thickness of honeycomb or Polymethacrylimide (PMI) foam core is usually manufactured by pre-bonded forming process, that is pre-forming panels and sandwich core, and then curing adhesive them to be sandwich structure. Welding process of large thin-walled panel causes the panel surface to be irregular and have greater errors relative to the design surface. Simply CNC machining the sandwich core according to the design surface cannot guarantee an exact match sandwich core consistent with the panels. The actual topography of the panels must be scanned. It is proposed that the use of a new hand-held laser scanner, Handyscan to scan large thin-walled curved surface parts, of Geomagic software to handle the acquired point clouds and construct the surface model.
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Ballere, Ludovic, Philippe Viot, Laurent Guillaumat, and Jean-Luc Lataillade. "OS14-3-3 Residual tensile strength of impacted curved panels." Abstracts of ATEM : International Conference on Advanced Technology in Experimental Mechanics : Asian Conference on Experimental Mechanics 2007.6 (2007): _OS14–3–3——_OS14–3–3—. http://dx.doi.org/10.1299/jsmeatem.2007.6._os14-3-3-.
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.
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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Shen, Hui-Shen, and X.-Q. He. "Large amplitude free vibration of nanotube-reinforced composite doubly curved panels resting on elastic foundations in thermal environments." Journal of Vibration and Control 23, no. 16 (December 16, 2015): 2672–89. http://dx.doi.org/10.1177/1077546315619280.
A large amplitude vibration analysis is presented for nanocomposite doubly curved panels resting on elastic foundations in thermal environments. The doubly curved nanocomposite panels are studied with the consideration of different types of distributions of uniaxial aligned single-walled carbon nanotubes (SWCNTs). The material properties of the functionally graded carbon nanotube-reinforced composites (FG-CNTRCs) are assumed to be graded in the thickness direction according to linear distributions of the volume fraction of CNTs and are estimated through a micromechanical model. The motion equations are based on a higher order shear deformation theory and von Kármán strain-displacement relationships. The thermal effects are also included and the material properties of CNTRCs are assumed to be temperature-dependent. The motion equations are solved by a two-step perturbation approach to determine the nonlinear frequencies of the CNTRC doubly curved panel. The numerical illustrations cover small- and large-amplitude vibration characteristics of CNTRC doubly curved panels resting on Pasternak elastic foundations. The present solutions also highlight the effects of CNT volume fraction, temperature variation, foundation stiffness, panel curvature ratio as well as in-plane boundary conditions on the nonlinear free vibration behaviors of CNTRC doubly curved panels.
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.
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.
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.
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.
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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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.
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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Sinclair, Gregory Maurice. "The response of singly curved fibre reinforced sandwich and laminate composite panels subjected to localised blast loads." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13328.
Includes bibliographical references. This report presents results from a study on the response of singly curved fibre reinforced polymer (FRP) sandwich and laminate panels subjected to localised blast loads. The aim of the project was to investigate and compare the blast mitigation potential of each panel type and the influence of curvature on the response. Three radii of curvature were examined for both panel types, namely infinite (flat), 1000mm and 500mm. The FRP laminate panels were designed to consist of 1-5 layers of Eglass fibre reinforced epoxy sheets. The FRP sandwich panels consisted of a PVC foam core with 6 layers of FRP sheets on either side. Vacuum infusion, with the aid of three moulds, was used to manufacture the panels. The average thicknesses and areal densities of the FRP sandwich and laminate panels were 18.7mm and 4.9mm; and 862-8g/1m2 and 8458-g/m2 respectively. Three point quasi-static flexural tests were conducted on FRP sandwich and laminate specimens where the localised compression failure beneath the central loading bar was evident on both types of structures. The presence of the core reduced the damage observed on the back face of the FRP sandwich specimens. Blast tests were conducted on a horizontal ballistic pendulum at the Blast Impact and Survivability Research Unit (BISRU), University of Cape Town. Localised blasts were generated by detonating circular cylinder PE4 plastic explosives, placed at a constant standoff distance of 10mm. The charge mass ranged from 10g to 32.5g across all the panels. The failure modes of the blast loaded panels were identified by a post-test inspection. The failure mode initiation charts for the F RP sandwich panels revealed that failure modes were initially observed on the front face sheet and core material with slight appearance of delamination on the back face sheet. Increasing the charge mass resulted in the rupture of the front face sheet and penetration of the core. Additional failure of the back face sheet was also evident as the charge mass increased. The failure mode initiation charts of the FRP laminate panels exhibited less severe failure modes across a greater charge mass range that eventually lead to complete fibre rupture at higher charge masses. Delamination of the front face sheet of the flat FRP sandwich panels was initially observed in the centre of the panel and spread into the exterior region for increasing charge mass. The failure of the core material initially reduced the delaminated area of the back face sheet, however once the rupture of the front face sheet occurred, the delaminated area of the front face sheet reduced and the delaminated area of the back face sheet increased. This was similar for the curved FRP sandwich panels except that the delaminated area was predominately parallel to the axis of curvature prior to rupture and perpendicular to the axis of curvature subsequent to rupture. Delamination in the flat FRP laminate panels was initially observed in the centre of the panel and along the clamped boundary. Increasing charge mass resulted in the delaminated region spreading across the panel. As with the FRP sandwich panels, the delaminated area of the curved FRP laminate panels was initially observed parallel to the axis of curvature prior to rupture. Debonding of the FRP sandwich panels was initially observed at both of the front and back interfaces. For the front interface, the debonded lengths were observed in the centre and in exterior test area of the panel, but only in exterior test area for the back interface. With the rupture of the front face sheet, the debonded length of the front interface decreased and the back interface increased and spread across the entire test area. The blast rupture threshold of the two panel types were compared in terms of largest charge mass resisted. For each radii category, the FRP laminate panels outperformed the FRP sandwich panels, namely by 5g for the flat panels (25g vs 20g) and 9g for the 1000mm curved panels (27.5g vs 18.5g). However, for the 500mm curved panels the FRP laminate and sandwich panels ruptured at identical charge masses of 27.5g.
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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.
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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Ghoor, Ismail B. "The response of concave singly curved fibre reinforced moulded sandwich and laminated composite panels to blast loading." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/27811.
Composite materials are increasingly being used in a wide range of structural applications. These applications range from bicycle frames and building facades to hulls of marine ships. Their popularity is due to the high specific strength and stiffness properties, corrosion resistance, and the ability to tailor their properties to a required application. With the increasing use of composites, there is a need to better understand the material and damage behaviour of these structures. In recent years, the increased frequency of wars and terror attacks have prompted investigations into composite failure processes resulting from air-blast. Most of the research has been focused on flat panels, whereas there is relatively little on curved structures. This dissertation reports on the effect of air-blast loading on concave, singly curved fibre reinforced sandwich and composite panels. Sandwich panels and equivalent mass glass fibre laminates were manufactured and tested. Three types of curvature namely a flat panel (with infinite curvature), a curvature of 1000 mm radius and a curvature of 500 mm radius were produced, to determine the influence of curvature on panel response. The laminates were made from 16 layers of 400 g/m² plain weave glass fibre infused with Prime 20 LV epoxy resin. The sandwich panels consisted of a 15 mm thick Airex C70:75 core sandwiched between the 12 layers of 400 g/m² plain weave glass fibre and infused with Prime 20 LV epoxy resin. This arrangement produced a balanced sandwich panel with 6 layers of glass fibre on the front and back respectively. For all panels, vacuum infusion was used to manufacture in a single shot process. Mechanical properties of samples were tested for consistency in manufacturing. It was found that mechanical properties of the samples tested were consistent with low standard deviations on tensile and flexural strength. The panels were tested in the blast chamber flat the University of Cape Town. Blast specimens were clamped onto a pendulum to facilitate impulse measurement. Discs of plastic explosive, with charge masses ranging from 10 g to 25 g, were detonated. After blast testing, a post-mortem analysis of the damaged panels was conducted. Post-mortem analysis revealed that the failure progression was the same irrespective of curvature for both the sandwich panels and the laminates. Sandwich panels exhibited the following failure progression: delamination, matrix failure, core crushing, core shear, core fragmentation, core penetration and fibre fracture. The laminates displayed the following progression: delamination, matrix failure and fibre fracture. Curved panels exhibited failure initiation at lower charge masses than the flat panels. As the curvature increased, the failure modes initiated at lower charge masses. For example, as the charge mass was increased to 12.5 g the front face sheets of the flat and the 1000 mm radius sandwich panels exhibited fibre fracture, but the 500 mm radius sandwich panel exhibited fibre fracture and rupture through the thickness of the front face sheet. The 500 mm radius laminate exhibited front face failure earlier (15 g) than the 1000 mm radius (22.5 g) and flat panel (20 g). Curved laminates exhibited a favoured delamination pattern along the curved edges of the panel for both 1000 mm and 500 mm radii laminates. As the curvature increased, more delamination was evident on the curved edges. The curved panels displayed more severe damage than flat panels at identical charge masses. Curved sandwich panels experienced through thickness rupture at 20 g charge mass whereas the curved laminates did not exhibit rupture at 25 g charge mass. The flat laminates were the most blast resistant, showing no through-thickness penetration at 25 g (the highest charge mass tested) and initiated failure modes at higher charge masses when compared to the other configurations.
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Durago, Joseph Gamos. "Photovoltaic Emulator Adaptable to Irradiance, Temperature and Panel Specific I-V Curves." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/541.
This thesis analyzes the design and performance of a photovoltaic (PV) emulator. With increasing interest in renewable energies, large amounts of money and effort are being put into research and development for photovoltaic systems. The larger interest in PV systems has increased demand for appropriate equipment with which to test PV systems.
A photovoltaic emulator is a power supply with similar current and voltage characteristics as a PV panel. This work uses an existing power supply which is manipulated via Labview to emulate a photovoltaic panel. The emulator calculates a current-voltage (I-V) curve based on the user specified parameters of panel model, irradiance and temperature. When a load change occurs, the power supply changes its current and voltage to track the calculated I-V curve, so as to mimic a solar panel. Over 250 different solar panels at varying irradiances and temperatures are able to be accurately emulated. A PV emulator provides a controlled environment that is not affected by external factors such as temperature and weather. This allows repeatable conditions on which to test PV equipment, such as inverters, and provides a controlled environment to test an overall PV system.
Horban, Blaise A. The effects of through the thickness delaminations on curved composite panels. Wright-Patterson Air Force Base, Ohio: Air Force Institute of Technology, Dept. of the Air Force, Air University, 1985.
Ko, William L. Open-mode debonding analysis of curved sandwich panels subjected to heating and cryogenic cooling on opposite faces. Edwards, Calif: National Aeronautics and Space Administration, Dryden Flight Research Center, 1999.
DiNardo, John E. The Phillips curve is back?: Using panel data to analyze the relationship between unemployment and inflation in an open economy. Cambridge, MA: National Bureau of Economic Research, 1999.
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.
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.
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.
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.
NASA Dryden Flight Research Center., ed. Open-mode debonding analysis of curved sandwich panels subjected to heating and cryogenic cooling on opposite faces. Edwards, Calif: National Aeronautics and Space Administration, Dryden Flight Research Center, 1999.
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.
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.
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.
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.
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.
Narita, Daisuke, and Yoshihiro Narita. "Analysis and Design of Curved Laminated Composite Panels under External Pressure." In Key Engineering Materials, 1271–74. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-456-1.1271.
Schmieder, Markus, and Peter Mehrtens. "Cladding Freeform Surfaces with Curved Metal Panels — a Complete Digital Production Chain." In Advances in Architectural Geometry 2012, 237–42. Vienna: Springer Vienna, 2013. http://dx.doi.org/10.1007/978-3-7091-1251-9_19.
Keshav, V., and S. N. Patel. "Dynamic Buckling of Laminated Composite Curved Panels Subjected to In-plane Compression." In Lecture Notes in Civil Engineering, 735–44. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0365-4_62.
Psarras, Spyridon, Raul Muñoz, Mazdak Ghajari, Paul Robinson, Domenico Furfari, Arne Hartwig, and Ben Newman. "Compression After Multiple Impacts: Modelling and Experimental Validation on Composite Curved Stiffened Panels." In Smart Intelligent Aircraft Structures (SARISTU), 681–89. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-22413-8_32.
Samavedam, G., D. Hoadley, and J. Davin. "Test Facility for Evaluation of Structural Integrity of Stiffened & Jointed Aircraft Curved Panels." In Springer Series in Computational Mechanics, 321–37. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-84364-8_22.
Nydick, Ira, Peretz Friedmann, and Xaolin Zhong. "Hypersonic panel flutter studies on curved panels." In 36th Structures, Structural Dynamics and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1995. http://dx.doi.org/10.2514/6.1995-1485.
Pottmann, Helmut, Alexander Schiftner, Pengbo Bo, Heinz Schmiedhofer, Wenping Wang, Niccolo Baldassini, and Johannes Wallner. "Freeform surfaces from single curved panels." In ACM SIGGRAPH 2008 papers. New York, New York, USA: ACM Press, 2008. http://dx.doi.org/10.1145/1399504.1360675.
Al-Jumaily, A. "An approximate vibration analysis of curved panels." In 41st Structures, Structural Dynamics, and Materials Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2000. http://dx.doi.org/10.2514/6.2000-1345.
Adler, R., and P. J. Desmares. "SAW Touch Systems on Spherically Curved Panels." In IEEE 1986 Ultrasonics Symposium. IEEE, 1986. http://dx.doi.org/10.1109/ultsym.1986.198754.
Yossef, Nashwa M., M. Hassanen, M. A. Dabaon, M. H. El-Boghdadi, and M. Alaghoury. "Bending Behaviour of Curved Thin-Walled Panels." In Structures Congress 2008. Reston, VA: American Society of Civil Engineers, 2008. http://dx.doi.org/10.1061/41016(314)230.
CHANDRASHEKHARA, K. "Thermal buckling of anisotropic laminated cylindrically curved panels." In 32nd Structures, Structural Dynamics, and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1991. http://dx.doi.org/10.2514/6.1991-915.
Ravi Kumar, L., P. K. Datta, and D. L. Prabhakara. "TENSILE BUCKLING AND VIBRATION BEHAVIOUR OF CURVED PANELS." In Proceedings of the Second International Conference. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812776228_0064.
Domb, Moshe, and Barry Leigh. "Refined Design Curves for Shear Buckling of Curved Panels Using Nonlinear Finite Element Analysis." In 43rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2002. http://dx.doi.org/10.2514/6.2002-1257.
Domb, Moshe, and Barry Leigh. "Refined design curves for compressive buckling of curved panels using nonlinear finite element analysis." In 19th AIAA Applied Aerodynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2001. http://dx.doi.org/10.2514/6.2001-1328.
Hu, Hsuan-Teh, and Hung-Wei Peng. "Optimization of Axially Compressed Laminated Curved Panels with Cutouts." In 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 20th AIAA/ASME/AHS Adaptive Structures Conference 14th AIAA. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2012. http://dx.doi.org/10.2514/6.2012-1390.
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.
DiNardo, John, and Mark Moore. The Phillips Curve is Back? Using Panel Data to Analyze the Relationship Between Unemployment and Inflation in an Open Economy. Cambridge, MA: National Bureau of Economic Research, August 1999. http://dx.doi.org/10.3386/w7328.
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.
