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Статті в журналах з теми "SKIN PANELS MADE"
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Abbasloo, Aslan, and Mohamad Reza Maheri. "On the mechanisms of modal damping in FRP/honeycomb sandwich panels." Science and Engineering of Composite Materials 25, no. 4 (July 26, 2018): 649–60. http://dx.doi.org/10.1515/secm-2015-0444.
Повний текст джерелаАнотація:
Abstract Sandwich panels made of fibre-reinforced plastic (FRP) skins and a honeycomb core can be effectively damped through the choice of the skin and especially of the core materials. Because the core is often highly damped, a lateral deflection that causes more shearing of the core than bending of the skin increases sandwich damping. Aside from the skin and the core material properties, the shearing/bending ratio depends on a number of other, often interacting, factors, including the sandwich planar as well as transverse dimensions, the particular modal pattern in which the panel vibrates and its relationship to the type of skin layup, as well as the panel end conditions. In the present work, using a simple, first-order shear deformation theory, damping results have been produced for simple modes of vibration of a sandwich panel comprising composite skins and a damped honeycomb core, demonstrating the mechanisms by which the above factors affect the FRP skin/honeycomb core sandwich damping.
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Mironov, Viktor, Mihails Lisicins, and Irina Boiko. "Sandwich Panels Made of Perforated Metal Materials." Solid State Phenomena 320 (June 30, 2021): 155–60. http://dx.doi.org/10.4028/www.scientific.net/ssp.320.155.
Повний текст джерелаАнотація:
Nowadays, the growing attention has focused on the sandwich-structured composites (panels), especially on those, which are environmentally friendly. The sandwich panel is a special type of the composites made of at least three layers: a core and a skin-layer bonded to each side. The aim of this paper is to investigate the possibility of using of perforated metallic materials for producing sandwich panels for the different application in the civil engineering. By using the perforated metallic materials in combination with different core materials or by using the perforated metallic material as the core material the wide range of products for the construction, damping or isolation purposes could be manufactured. In the paper the example of using of perforated metallic sheet materials for manufacturing the sandwich panels is proposed. Both, the simulation and experimental studies (mechanical testing) were carried out in order to assess the load-bearing capacity of sandwich panels and to prove the applicability of the proposed sandwich panels for construction structures. For the analysis of the achieved structures the finite element analysis (FEA) software was used. The simulation results are well-coincided with the results of the experimental studies. Thus, new types of the sandwich panels and the manufacturing technology thereof are shown its reliability and could be recommended for application in the different branches, in particular for producing lightweight ceiling panels with filler from heat insulating materials.
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Fajrin, Jauhar, Ni Nyoman Kencanawati, Miko Eniarti, and Arismanto Arismanto. "Core Configuration Effect On The Flexural Behaviour Of Sandwich Panel Made Of Aluminium Skin And Sengon Wood Core." Jurnal Rekayasa Sipil (JRS-Unand) 17, no. 3 (February 26, 2022): 186. http://dx.doi.org/10.25077/jrs.17.3.186-193.2021.
Повний текст джерелаАнотація:
Among the many choices of composite sandwich panel cores, Balsa wood is one of the main alternatives of cores made of wood. However, the availability and price of Balsa wood are quite expensive, so it needs alternatives from other types of wood such as Sengon wood. The purpose of this study was to evaluate the feasibility of Sengon wood as a core of composite sandwich panels. Three variations of the Sengon wood layout had been prepared as the core of the sandwich panels with a skin made of aluminum. All specimens, including the control specimens made of whole Sengon wood, were prepared with a size of 550 x 50 x 24 mm for length, width, and depth, respectively. Each variation and also the control specimens were made of 3 pieces. Tests were carried out based on the ASTM C 393-94 standard under the three-point bending test scheme. The results showed that the sandwich panel with plain Sengon wood core has the highest capacity to carry a flexural load, which is approximately 177.391 MPa, followed by a sandwich panel with long and end grain Sengon board that possess flexural strength of 153.913 MPa and 79.101 MPa, respectively. The flexural strength of these sandwich panels is superior to solid Sengon wood. The sandwich panels showed a typical ductile material indicated by a non-linear curve without a distinct yielded point before reach the maximum failure load. Three sandwich panels with various Sengon wood cores collapsed under three types of failure mechanisms; face wrinkling, shearing of the core, and delamination between the interface of skin and core. In conclusion, Sengon wood has a great potential to be used as the core material for a composite sandwich panel.
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Mohamad, Noridah, and Hilmi Mahdi Muhammad. "Testing of Precast Lightweight Foamed Concrete Sandwich Panel with Single and Double Symmetrical Shear Truss Connectors under Eccentric Loading." Advanced Materials Research 335-336 (September 2011): 1107–16. http://dx.doi.org/10.4028/www.scientific.net/amr.335-336.1107.
Повний текст джерелаАнотація:
This paper reports the structural behavior of precast lightweight foamed concrete sandwich panel, PLFP, subjected to eccentric loading. An experiment was conducted to investigate the structural performance of PLFP under this load. Two PLFP panels, PE-1 and PE-2 were cast with 2000 mm in heights, 750 mm in width and 100 mm in thickness. The thickness of the wall is actually a combination of three layers. Skin layers were cast from lightweight foamed concrete while the core layer is made of polystyrene. The skin layers were connected to each other by 9 mm steel shear truss connector which were embedded through the layers. Panel PE-1 was strengthened with single diagonal shear truss connectors made of 6 mm steel rebar while panel PE-2 was strengthened with symmetrical diagonal shear truss connectors of similar steel diameter. Both panels were tested under eccentric load till failure. The results showed that panel with symmetrical double truss connectors, PE-2, is able to sustain higher load compared to panel with single shear truss connector. The load-deflection profiles indicate that both panels achieved certain degree of composite action especially during the later stage of loading where the wythes tend to move in the same direction until they reached failure. The load-strain curves for both panels highlight the inconsistent distribution of surface strain along the height of panels. The overall trend of the strain curves show that they are under compression.
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Yuen, Steeve Chung Kim, Gerald Nurick, and Misha C. du Plessis. "Response of Sandwich Panels with Tubular Cores to Blast Load." Applied Mechanics and Materials 566 (June 2014): 581–85. http://dx.doi.org/10.4028/www.scientific.net/amm.566.581.
Повний текст джерелаАнотація:
This paper reports on the response of cladding sandwich panels with tubular cores to uniform blast load. The panels consist of thin-walled circular tubes (38 mm in diameter) made from aluminium 6063-T6 riveted laterally between the skin plates at varying spacing arrangements to provide four different types of panels. The skin exposed to the blast load is made from DOMEX 700 Steel while the back face skin is made from mild steel. Varying charge masses of explosive (ranging from 5 g to 40 g) with a prescribed load diameter of 40mm is detonated at a stand-off distance of 200 mm to provide a “uniform” blast load to the sandwich panels. Energy is dissipated mostly through the plastic deformation of the tubular cores. The results show an increase in average deflection with an increase in charge mass/impulse for the different types of panels. The cladding panels with the least interaction between the tubular cores are observed to have the highest energy absorption capabilities for a given charge mass.
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Pereira, Meyrick, Maziar Ramezani, Timotius Pasang, and Ben Withy. "Investigation of Polyurethane Bonding to Steel in Sandwich Panels." Materials Science Forum 890 (March 2017): 401–5. http://dx.doi.org/10.4028/www.scientific.net/msf.890.401.
Повний текст джерелаАнотація:
Sandwich panels made of thin and stiff skins, connected by a thick and soft core are widely used in load-bearing components mainly due to their high strength to weight ratio. To improve the reliability in using sandwich beams, it is necessary to understand their responses under external mechanical and environmental stimuli. This paper investigates the construction of steel-polyurethane-steel sandwich panels and their mechanical properties. Key properties of a sandwich structure are the adhesion between the skins and the sandwich material, and the load transfer from the outer skin to the inner skin. Lap shear specimens were selected to give an indication of the bond strength of the polyurethane to steel, whilst three point bend test specimens were selected to indicate the degree of load transfer between the skins and the bending resistance provided by the sandwich structure.
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Luengo, Emilio, Francisco Arriaga, Ignacio Bobadilla, and Eva Hermoso. "Mechanical Efficiency and Quality Control Preliminary Analysis of Incompletely Bonded Wood-Based Sandwich Panels." Forests 14, no. 6 (May 23, 2023): 1074. http://dx.doi.org/10.3390/f14061074.
Повний текст джерелаАнотація:
Wood-based sandwich panels are building products composed of two skins attached to a lightweight continuous core in which at least one skin is made of wood-based products, contributing to the use of renewable forest goods. Since the connection between the skins and the core is often provided by adhesive bonding, its characteristics affect the mechanical behavior of the sandwich and, therefore, must be thoroughly assessed. Full adhesion is often considered the standard situation, although some batches of the commercial product show incompletely glued surfaces, and scarce data is available with regard to their bonding performance. For this reason, analyses were performed using tensile tests with a load perpendicular to the skins and specific shear tests with a load parallel to the longitudinal direction of the panel. The test samples were obtained from wood-based sandwich panels with extruded polystyrene cores and different skin materials. The tensile tests proved to be suitable only for panels with adequate skin material cohesion, their functionality improving as a control method when the glued surface percentage assessment is used together with the tensile strength. The results of the shear tests provided non-linear models relating the effect of the glued surface to the mechanical properties, revealing that the mechanical efficiency of the incompletely bonded specimens is better than that which might be expected if the core only worked in proportion to the glued surface, due to the help of the adjoining non-glued core material.
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Hoxha, Dashnor, Brahim Ismail, Ancuța Rotaru, David Izabel, and Thibaut Renaux. "Assessment of the Usability of Some Bio-Based Insulation Materials in Double-Skin Steel Envelopes." Sustainability 14, no. 17 (August 30, 2022): 10797. http://dx.doi.org/10.3390/su141710797.
Повний текст джерелаАнотація:
In this paper, a double-skin steel building-demonstrator, set up using panels of five bio-based insulators and a classical mineral insulating material, is studied. The panels used in the demonstrator are made from industrially manufactured and commercialized bio-materials. To assess the suitability of these panels for use in cold formed steel envelope buildings, their advantages and/or the drawbacks (if any) of the synchronized records of temperatures, relative humidity and thermal flux of each panel are obtained using a system of continuous measurements. Data from 6 months of records in the roof of the demonstrator are used to assess the infield properties of the panels and the seasonal evolution of these properties in relation to the presence of the vapor barrier. The thermal resistance of each panel is determined from these data using two methods: the ISO 9869-1:2014 based on the Heat Flow Meter (HFM) method and an inverse problem identification method. All bio-sourced panels manifest higher thermal resistance than the classical insulation system, whatever conditions of use with or without barrier vapor. The seasonal variations of thermal properties are attenuated when a vapor barrier is used. No risk for water condensation inside the bio-insulations is revealed so far.
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Grenestedt, Joachim L., and Mikael Danielsson. "Elastic-Plastic Wrinkling of Sandwich Panels With Layered Cores." Journal of Applied Mechanics 72, no. 2 (March 1, 2005): 276–81. http://dx.doi.org/10.1115/1.1828063.
Повний текст джерелаАнотація:
Elastic-plastic wrinkling of compression loaded sandwich panels made with layered cores was studied analytically and experimentally. A core with a stiff layer near the sandwich skins can improve various properties, including wrinkling and impact strengths, with only a minor weight penalty. The 2D plane stress and plane strain bifurcation problems were solved analytically, save for a determinantal equation which was solved numerically. Experiments were performed on aluminum skin/foam core sandwich panels with different combinations of stiff and soft core materials. Good correlation between experiments and theory was obtained.
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Elnasri, Ibrahim. "Impact perforation of sandwich panels with graded hollow sphere cores: Numerical and Analytical investigations." EPJ Web of Conferences 250 (2021): 02027. http://dx.doi.org/10.1051/epjconf/202125002027.
Повний текст джерелаАнотація:
In this study, we numerically and analytically investigate the impact perforation of sandwich panels made of 0.8 mm 2024-T3 aluminum alloy skin sheets and graded polymeric hollow sphere cores with four different gradient profiles. A suitable numerical model was conducted using the LS-DYNA code, calibrated with an inverse perforation test, instrumented with a Hopkinson bar, and validated using experimental data from the literature. Moreover, the effect of boundary conditions on the perforation resistance of the studied graded core sandwich panels was discussed. The simulation results showed that the piercing force– displacement response of the graded core sandwich panels is affected by the core density gradient profiles. Besides, the energy absorption capability can be effectively enhanced by modifying the arrangement of the core layers with un-clumping boundary conditions in the graded core sandwich panel, which is rather too hard to achieve with clumping boundary conditions. Finally, an analytical model, taken account only gradient in the quasi-static plateau stress, is developed to predict the top skin pic peak load of the graded sandwich panel.
Дисертації з теми "SKIN PANELS MADE"
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SINGH, ASHWANI KR. "SIMULATION OF CRASH TEST OF A SALOON CAR WITH SKIN PANELS MADE OF IF AND AHS STEEL." Thesis, 2020. http://dspace.dtu.ac.in:8080/jspui/handle/repository/18162.
Повний текст джерелаАнотація:
Car crash test analysis is widely performed to determine the level of safety provided
by the car to its passengers. This thesis focusses on the similar study. There are
several factors which contribute to the safety of passengers, specially front seat
travellers based on which the star ratings are provided to every car by the standard
testing organisations.
The study involves all the standards as set by NCAP and also uses the model of
Toyota Yaris with the conditions and specifications assigned to it by NCAP
officially. The FE model was observed on the software LS-Dyna. The study of the
car involves material change for the skin and frame of the car on software. The new
material whose specifications were used on the software were IF (Interstitial Free)
steel for the skin material and AHSS(Advanced High Strength Steel) for the frame
which require comparatively higher strength. The tensile testing results were
obtained which were helpful in defining the Load Curves for the respective materials.
The load curves were used in the software simulation for definition of material
deformation in its plastic state.
The simulation in full frontal orientation which is one of the standard tests involved
in Crash analysis was performed with changed material. The results and observations
have been limited to the materials’ properties during impacts. Although there are
numerous factors which involve the safety of a vehicle, the focus was primarily on
the skin and frame material change which can increase the crashworthiness and make
vehicle safer. The crash pulse and energy absorption was primarily focussed directly
v
determining the materials’ effectiveness in crash. Also, the deceleration curve and
velocity curve for the driver’s seat was drawn with respect to time in order to
determine effect of the change of material on the shock propagation through the car
body.
The net increase in the energy absorption was slightly less than 2 percent which is
small but significant taking into the account of others parameters which have been
excluded like the change in parameters for the Cowper-Symonds material model.
Also, the average decrease in acceleration and velocity of the driver’s seat was less
than 2 percent too. Along the thesis, the reason can be discerned behind this increase
and decrease which is primarily based on the limitations and assumptions.
Based on those results, the thesis concludes the study with the scope of work that can
be done in future with relaxation in the limitations.
Частини книг з теми "SKIN PANELS MADE"
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Hussein, Rafaat. "Treatise on Sustainable Infrastructure Construction: Green Composites, Cross Laminated/Mass Timber, Wood Truss Connectors, Nondestructive Technologies, Health Assessment and Monitoring: Utility Poles and Geofoam." In Advances and Technologies in Building Construction and Structural Analysis. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95850.
Повний текст джерелаАнотація:
The understanding of the engineering performance of green laminated composites is necessary to the design of load bearing components in building and infrastructure construction, and packaging applications. These components are made of outer thin laminae called skins or faces and a thick inner layer called core. The use of bonding is unavoidable in the assembling of these composite products. Like all materials, the bonding materials have finite mechanical properties, e.g. stiffness, but when used in the literature, they are assumed perfectly rigid. That is an unrealistic assumption. Our analytical solutions change this assumption by using the real properties of bonding. In general, the analytical formulations are based on the equilibrium equations of forces, the compatibility of interlaminar stresses and deformation, and the geometrical conditions of the panels. Once solutions are obtained, the next step is to evaluate them. The numerical evaluations proved that perfect rigid bonding in laminated composites greatly underestimates the true performance. At low values of adhesive stiffness, the serviceability is multiple orders of magnitude of that at high values. The logical question is thus: what constitutes perfect bonding? The answer to this question lies in the core-to-adhesive stiffness. The lower the ration is the higher the error in using the rigid-bond theories. It is worth noting that green-composites in this chapter refer to components made of traditional materials such as wood, in addition to newly developed bio-based and bio-degradable and bio-based composites, made of renewable resources. In addition, bonding and adhesive are used interchangeably.
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Engovatova, Asya, Kharis Mustafin, Irina Alborova, Alexander Kanapin, Anastasia Samsonova, and Maria Mednicova. "New Data on the Fatyanovo Culture: Analysis of Ancient DNA in the Burials of the Volosovo-Danilovsky Burial Ground." In The footsteps of my friends leaving ... Ad memoriam Oleg Sharov, 115–28. Stratum plus I.P., High Anthropological School University, 2022. http://dx.doi.org/10.55086/sl22115128.
Повний текст джерелаАнотація:
The Fatyanovo archaeological culture, which spread over the territory from Ilmen and Pskov Lake to Kama and Vyatka and from the Vologda region to the Desna river, today is called the “forgotten child” of a large family of Corded Ware cultures. In recent years, the study of the origin of the Fatyanovo people, in many respects, depends on the results of the analysis of ancient DNA. The archaeological DNA of 11 male individuals of the Bronze Age belonging to the Fatyanovo culture from the Volosovo-Danilovo burial ground were comprehensively studied. The STR markers of the Y chromosome were determined by the method of fragment analysis. The obtained haplotypes were indicative of the unity of the haplogroup of the studied individuals, but also of the absence of a close relationship between them. According to the results of NGS performed using a custom panel, SNP markers determining the Y-chromosomal haplogroup R1a (Z93) were reliably (with high coverage) identified, phenotypic signs, such as eye color — brown, hair color — dark, skin color — intermediate. The analysis of the signs of authenticity of archaeological DNA was carried out, the degree of contamination was assessed. The methods of bioinformatic analysis based on the results of NGS of the autosomal part of DNA demonstrated the similarity of the results of sequencing of the studied archaeological DNA samples published earlier, obtained for samples belonging to the Fatyanovo culture by another team of researchers who had used a different method.
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Majid, D. L., Nor Hafizah Manan, and Yee Ling Chok. "Honeycomb Composite Structures of Aluminum: Aerospace Applications." In Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000279.
Повний текст джерелаАнотація:
A honeycomb composite structure is usually composed of a lightweight hexagonal core sandwiched between two thin face sheets that are adhesively joined. Both the core and the face sheets can be combinations of many types of materials depending on the application. In this article, an overview of the design and manufacturing process of aluminum honeycomb composite structures particularly for aerospace application is presented. Aluminum honeycomb composite structures are lightweight constructions with high specific strength and stiffness that are applied mainly in the aerospace industry. An aluminum honeycomb panel is typically made up of the secondary structural components and interiors of an aircraft such as the wing skin, trailing edge, control surface, flooring, partitions, aircraft galleys, and overhead bins, to name a few. Other applications are in the spacecraft, helicopter, missile, and satellite. Owing to its honeycomb design peculiar to the hexagonal beehives, it can reach more than 30 times higher in stiffness and 10 times higher in flexural strength compared to its solid counterpart of the same weight. The mechanical properties of the honeycomb composite structure hinge on the materials of the core and face sheets, the core geometries, and the thickness of the face sheets. Designed for superior flexural and shear loading, the selection of the optimal honeycomb design will depend on the application requirements. The principal design criterion of a sandwich structure in aerospace applications is weight saving, and there is a trade-off between performance and cost. In terms of manufacturing of the honeycomb composite sandwich structure, the two main processes are the expansion process commonly used for low-density cores and the corrugation process for higher density cores.
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Hal, Stephen S. "Human Cloning and Stem Cells." In A Field Guide for Science Writers. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195174991.003.0036.
Повний текст джерелаАнотація:
Of the countless interviews I have conducted with scientists over the years, only once has a question prompted something of a striptease. In December of 1999, I found myself in the elegant parlor of the Union Club in New York City, chatting with a biologist named Leonard Hayflick. Although hardly a household name to the general public, Hayflick is that rare scientist whose name is permanently attached to a biological phenomenon. It is known as the “Hayflick limit,” and it derives from experiments he did in the late 19505 and early 19605 showing that human cells grown in Petri dishes will predictably replicate for a certain number of cell divisions, but then hit a wall and stop dividing. This has obvious implications for cell biology, aging, and immortality (of the in vitro sort), and indeed the Hayflick limit has been the seed around which a spirited biological debate about the biology of aging has swirled, without definitive resolution, for about four decades now. Because of this history, Hayflick has closely followed the recent work on the biology of aging and regenerative medicine, which in turn has made him a front-row spectator in the more recent controversies involving human embryonic stem cell research and “therapeutic cloning.” At the time of my conversation with Hayflick, his longtime friend Michael West was attempting to obtain human embryonic stem cells through cloning—in a particularly controversial way, by putting human cells into egg cells from ... cows. Almost as an aside, I asked Hayflick what he thought about West's experiments. Hayflick replied by rolling up his pants leg. He bared enough skin to be able to point out a tiny dimple on his right knee. “The human cells he's using for the cow work came from here,” he said. I had to stand up and lean over to see it, but there was undeniably a tiny divot in Hayflick's skin. The implications were stunning: Leonard Hayflick, the father of cellular senescence and one of the elder statesmen of gerontology, was allowing himself, in a manner of speaking, to be cloned. In addition to making the obvious point that even the most innocuous question can elicit a startling answer, Hayflick's reply offered another lesson, too: that colorful characters can provide a narrative thread for bringing a controversy to life.
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Laslie, Brian D. "Introduction." In Architect of Air Power. University Press of Kentucky, 2017. http://dx.doi.org/10.5810/kentucky/9780813169989.003.0001.
Повний текст джерелаАнотація:
On 30 September 1974, General Laurence S. Kuter, US Air Force retired, sat on a small chair in his apartment in Naples, Florida. He wore an open-collar button-down short-sleeved shirt and pants with a pattern of crossed golf clubs. His skin was a deep bronzed color thanks to the days in retirement spent on the golf courses of the southwestern Florida coastal city. At nearly seventy years of age, he still looked every part an air force general. With the general in his apartment sat two air force historians who were there to conduct an oral history interview to preserve the historical value of the general’s life from his earliest days through World War I and his experiences in the newly formed US Air Force of the 1940s, 1950s, and 1960s. It was part of a program that Brigadier General Kuter himself authorized in the early days of American involvement in World War I when he directed that the Air Staff Historical Section gather history “while it is hot” and that “personnel be selected and an agency set up for a clear historian’s job without axe to grind or defense to prepare.” That directive, signed in July 1942, and the documents, interviews, mission reports, and other items collected during the war became the nucleus of the official archives of the US Air Force, now held at the Air Force Historical Research Agency. This was made possible because Kuter directed that that material be collected, preserved, and archived. Kuter himself might have been unaware at the time that so much of his own story would be captured by this program and that years later his personal remembrance of events would itself be archived away as an official report....
Тези доповідей конференцій з теми "SKIN PANELS MADE"
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Takeichi, Michifumi, Sumio Okuno, Masato Okazaki, Hitoshi Tsuruda, and Shunichi Kawano. "Static Strength Properties of an Aluminum Alloy Honeycomb Sandwich Panel and Strength Reliability Evaluation of an Actual Car Body Structure." In ASME 2002 Pressure Vessels and Piping Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/pvp2002-1214.
Повний текст джерелаАнотація:
The hollow extrusion-type material made from aluminum alloys has recently attracted attention, and it has been used for the car bodies of high-speed railway vehicles. Hollow extrusions are laminating board structures that consist of a two-sheet board and slanting material known as a double skin structure. The double skin structure is advantageous in attaining a lightweight car body structure and in increasing rigidity in case it bends outside and the pressure load at the time of the run in tunnel acts, since rigidity is high. In this study, static tests were carried out for component models and for an experimental full-sized car body, in which aluminum honeycomb panels are applied as outside plates to improve pressure resistance, while their requisite light weight and rigidity are maintained. Experiments were conducted to determine tensile strength, bending strength and the shearing strength of the honeycomb panel. The stresses of an actual car body were under 30 MPa, which is low compared with strength of the honeycomb panel. An actual car body, then, has sufficient strength reliability.
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GOYAL, VIJAY K., AUSTIN PENNINGTON, and JASON ACTION. "PROGRESSIVE DAMAGE FAILURE ANALYSIS OF POST-BUCKLED COMPOSITE SINGLE-STRINGER PANEL WITH TEFLON INSERTS." In Thirty-sixth Technical Conference. Destech Publications, Inc., 2021. http://dx.doi.org/10.12783/asc36/35773.
Повний текст джерелаАнотація:
The high strength-to-weight and stiffness-to-weight ratio materials, such as laminated composites, are advantageous for modern aircraft. Laminated composites with initial flaws are susceptible to delamination under buckling loads. PDA tools help enhance the industry’s understanding of the mechanisms for damage initiation and growth in composite structures while assisting in the design, analysis, and sustainment methods of these composite structures. The global-local modeling approach for the single-stringer post-buckled panel was evaluated through this effort, using Teflon inserts to simulate the defect of damage during manufacturing. This understanding is essential for designing the post-buckled structure, reducing weight while predicting damage initiation location, and addressing a potential design review for future aircraft repairs. In this work, the initial damage was captured with Teflon inserts as the starting configuration; and any reference to the damage initiation refers to any damage beyond the “initial unbonded region.” The effort aims to develop, evaluate, and enhance methods to predict damage initiation and progression and the failure of post-buckled hat-stiffened panels using multiple Abaqus FEA Virtual Crack Closure Technique (VCCT) definitions. Validation of the PDA using the VCCT material model was performed on a large single-stringer panel subjected to compressive loading. The compressive loading of the panel caused the skin to buckle before any damage began to occur locally. In addition, comparisons are made for critical aspects of the damage morphology, such as a growth pattern that included delamination from the skin-stiffener interface to the skin and ply interfaces. When compared against the experimental data produced through the NASA Advanced Composites Project (ACP), the present model captured damage migration from one surface to another, and model validations were ~5% of the experimental data.
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Kella, Caroline Karishma, and Pankaj Mallick. "Formability Analysis of Aluminum-Aluminum and AA5182/Polypropylene/AA5182 Laminates." In WCX SAE World Congress Experience. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2023. http://dx.doi.org/10.4271/2023-01-0731.
Повний текст джерелаАнотація:
<div class="section abstract"><div class="htmlview paragraph">Owing to their weight saving potential and improved flexural stiffness, metal-polymer-metal sandwich laminates are finding increasing applications in recent years. Increased use of such laminates for automotive body panels and structures requires not only a better understanding of their mechanical behavior, but also their formability characteristics. This study focuses on the formability of a metal–polymer-metal sandwich laminate that consists of AA5182 aluminum alloy as the outer skin layers and polypropylene (PP) as the inner core. The forming limit curves of Al/PP/Al sandwich laminates are determined using finite element simulations of Nakazima test specimens. The numerical model is validated by comparing the simulated results with published experimental results. Strain paths for different specimen widths are recorded. The variation of the forming limit curves with different thickness combinations of the outer skins and inner layer is determined to understand the effect of skin-to-core thickness ratio on the formability. Additionally, a comparison of the sandwich laminates with single aluminum sheets and aluminum-aluminum laminates of equivalent thickness is made to understand the advantage of the presence of the polymer core on the limit strains. Investigations are also made on layered aluminum laminates with varying friction between the two sheets to gain insight on the advantage of the presence of bonding between the layers in Al/Al laminates.</div></div>
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Asheghian, Laila, Greg Reich, Andrew Enke, and Jay Kudva. "Shear Morphing Skins: Simulation and Testing of Optimized Design." In ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2010. http://dx.doi.org/10.1115/smasis2010-3913.
Повний текст джерелаАнотація:
NextGen’s work on the DARPA sponsored Next Generation Morphing Aircraft Structures (N-MAS) program [1]–[6] designed and successfully tested novel morphing wing designs that were enabled by “shear-morphing” skins capable of withstanding up to 400 psf air-loads while simultaneously undergoing shear strains in excess of 100%. These ad-hoc skin designs consisted of high-strain silicone facesheets supported by an intricate aluminum under-structure made of thin, closely-spaced aluminum ribbons glued to the facesheets and bounded by pin-jointed frames. While these performed well in wind tunnel and flight tests, two areas for improvement were identified: (1) reduction in manufacturing complexity, and (2) reduction in actuation force requirements. In this research program, through use of high-fidelity modeling (ANSYS) and in-house testing, a new design was obtained that met both of the desired objectives using novel materials and single-piece support structure fabrication. The optimization modeling code was designed to be adaptable to a range of design inputs, and as such can be used on future programs as well, at various scales from UAV to MAV. The thorough understanding of the design space gained from non-linear FEM modeling guided design, manufacturing and testing in the later portion of the research. Using the optimized design from analysis, as well as variations in facesheet prestrain, the ANSYS code was validated through manufacture and testing of panels. This report details the results of testing and compares them to both predictions of the ANSYS code and N-MAS baseline designs values through various test setups. Results presented include shear morphing forces/energy, out-of-plane displacement under air loading, and 3D photometric analysis of shearing panels for identification of stresses/strains and wrinkling initialization in the skin. Testing provided substantiation of the ANSYS code, matching the general predicted trends despite wide variability in material properties.
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OLIVERI, VINCENZO, GIOVANNI ZUCCO, MOHAMMAD ROUHI, ENZO COSENTINO, RONAN O’HIGGINS, TREVOR M. YOUNG, and PAUL M. WEAVER. "DESIGN AND ANALYSIS OF AN INTEGRATED THREE- BAY THERMOPLASTIC COMPOSITE WINGBOX." In Thirty-sixth Technical Conference. Destech Publications, Inc., 2021. http://dx.doi.org/10.12783/asc36/35766.
Повний текст джерелаАнотація:
The design of a multi-part aerospace structural component, such as a wingbox, is a challenging process because of the complexity arising from assembly and integration, and their associated limitations and considerations. In this study, a design process of a stiffeners-integrated variable stiffness three-bay wingbox is presented. The wingbox has been designed for a prescribed buckling and post-buckling performance (a prescribed real testing scenario) and made from thermoplastic composite material system (Carbon-PEEK) with the total length of three meters. The stiffeners and spars are integrated into the top and bottom panels of the wingbox resulting a single-piece blended structure with no fasteners or joints. The bottom skin also has an elliptical cut-out for access purposes. The composite tows are steered around this cutout for strain concentration reduction purposes. The fiber/tow steering in the top skin bays (compression side) has also been considered for improved compression-induced buckling load carrying capacity. The proposed design has been virtually verified via high fidelity finite element analysis.
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Basu, D., A. Hamed, and K. Das. "DES, Hybrid RANS/LES and PANS Models for Unsteady Separated Turbulent Flow Simulations." In ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77421.
Повний текст джерелаАнотація:
This paper presents computational results for two DES (Detached Eddy Simulation), one hybrid RANS (Reynolds Averaged Navier-Stokes)/ LES (Large Eddy Simulation) and some preliminary results from PANS (Partially Averaged Navier-Stokes) turbulence for simulation of unsteady separated turbulent flows. The models are implemented in a full 3-D Navier Stokes solver and are based on the two-equation k-ε model. The formulations of each model are presented and results are analyzed for subsonic flow over a Backward Facing Step (BFS). Simulations are carried out using a 3rd order Roe scheme. A comparative assessment is made between the predictions from the DES, hybrid and PANS models. The predicted results are compared with the available experimental data for skin-friction coefficient, and different turbulent quantities. The three-dimensionality of the flow field and the separated fine scale structures are presented through the Q iso-surfaces.
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Rotariu, Mariana, Mihai Ilea, and Calin Corciova. "A SIMPLE EDUCATIONAL TOOL FOR MATHEMATICAL MODEL OF SKIN ABSORPTION FOR BIOMEDICAL ENGINEERING STUDENTS." In eLSE 2020. University Publishing House, 2020. http://dx.doi.org/10.12753/2066-026x-20-204.
Повний текст джерелаАнотація:
Biomedical Engineering (BME) is different from other engineering or medical areas, in the sense that the results are obtained usually by experimental procedures and the simulation using mathematical approaches are familiar to them without a very deep knowledge of medical subjects specific to physicians. The tool proposes one and two compartment models for mathematical model of skin absorption selected from models in literature. The compartments models are described by system of differential equations that are solved by numerical methods. The user has the possibility to select the model and the parameters of the models (the Graphical User Interface - GUI) is automatically updated according the selected model along with a graphical image of compartments and the variables that are assigned to interaction among compartments. The parameter for simulation (the solving of system of differential equations) are adjusted optimally according to selected model but they can be also modified by the user in order to test the sensitivity of the models to different value of parameters. The dosage substrate and/or inhibitors can be calculated by user using this tool. The constant of permeability and diffusion, deduced by experimental data, can be included and saved for future use using a selection panel. The implementation is made as a Matlab application with a GUI designed as a friendly user interface. The graphic of evolution of variable are displayed in a window, and the user has the possibility to select the group of variables to be visualized. The tool is accompanied by a small user's manual with a set of practical tests in the form of laboratories in order to improve the e-learning process. A more concise form of the mathematical model can be used by students in Balneo-Physio-Kinetotherapy (BFKT) by simulated be the Sulphur absorption by skin in sludge therapy.
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Silvério, Gabriel André, Pedro Arthur Possan, Mateus Pinto Marchetti, Isabela Louise Weber, Vera Cristina Terra, Karen Luiza Ramos Socher, Nancy Watanabe, and Carlos Cesar Conrado Caggiano. "Multiple cranial couple syndrome secondary to neurosyphilis: case report." In XIV Congresso Paulista de Neurologia. Zeppelini Editorial e Comunicação, 2023. http://dx.doi.org/10.5327/1516-3180.141s1.548.
Повний текст джерелаАнотація:
Male, 62-year-old, with Type 2 Diabetes Mellitus, seeks care due to altered balance and worsening palpebral ptosis. The patient had had peripheral facial palsy on the left for 40 days and was treated at another institution with oral prednisone and acyclovir for three days. Ten days ago, he had started with ipsilateral palpebral ptosis, associated with binocular diplopia and divergent strabismus also on the left in the primary gaze position. He also complained that during this period he had worsened visual acuity and frequent falls, which he related to imbalance. Upon inspection, he presented maculopapular erythema on the back, abdomen and upper limbs, with ptosis on the left. On examination, he still had a stomping and dysbasic gait, paralysis of the II, III, and IV nerves bilaterally, as well as of the VII, IX, and X on the left, with reduced visual acuity bilaterally (worse on the left), in addition to a positive Romberg test — with a fall to the left. Furthermore, there was hyporeflexia in the biceps and triceps bilaterally, associated with areflexia in the Achilles and patellas, with symmetrical distal apalesthesia in the four limbs, and cutaneousplantar in bilateral flexion. Magnetic resonance imaging of the head and neck showed uptake by the contrast medium seen at the bottom of the internal auditory canal in the distal meatal and labyrinthine segments of the left facial nerve, without signs of intracranial expansive lesion and without detectable cervical abnormalities. Laboratorially, the patient had a positive treponemal test with a Venereal Disease Research Laboratory (VDRL) value of 1:128 and the serum test for Borrelia burgdorferi showed positivity for immunoglobulin G (with negative immunoglobulin M) on admission, and such tests were repeated and negative prior to discharge, probably being altered due to cross reaction, despite the history of travel for about two years to an endemic area (Canada). Rheumatological tests, tumor and granulomatous disease markers, and serology were negative. When studying the cerebrospinal fluid, we found pleocytosis with lymphomonocytic predominance and hyperproteinorrhachia, with negative VDRL and panel for meningitis. Therefore, the hypothesis of neurosyphilis causing involvement of multiple cranial nerves was suggested and treatment with intravenous crystalline penicillin G was started for 14 days. After the first day of antibiotic therapy, the skin lesions became more prominent (Jarisch-Herxheimer reaction), with spontaneous disappearance in the subsequent days. Even during hospitalization, the patient evolved with gradual improvement of the ptosis on the left, absence of tongue deviation to the right and partial improvement in gait. Intravenous antibiotic therapy was completed, rehabilitation was indicated and outpatient return was planned.
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Alves, Renata Cristine, Gabriel André Silvério, Pedro Arthur Possan, Mateus Pinto Marchetti, Isabela Louise Weber, Vera Cristina Terra, Karen Luiza Ramos Socher, Nancy Watanabe, and Carlos Cesar Conrado Caggiano. "Urinary retention as an initial manifestation of adrenomyeloneuropathy." In XIV Congresso Paulista de Neurologia. Zeppelini Editorial e Comunicação, 2023. http://dx.doi.org/10.5327/1516-3180.141s1.539.
Повний текст джерелаАнотація:
Patient RMS, male, 38-year-old, previously dyslipidemic, was admitted to the emergency complaining of severe abdominal pain in the lower abdomen, diaphoresis, and acute retention, after drinking alcohol (ingestion of six glasses of beer). After being submitted to a urinary catheter — with a flow of 2000 ml of urine-, the patient showed instantaneous improvement in pain complaints and diaphoresis, remaining asymptomatic afterwards. He reported a previous feeling of mild difficulty -eventual- to urinate in recent years. He denied constipation or associated erectile dysfunction. Upon neurological examination, the patient was alert, preserved mental state, oriented in timespace-person, mobilizing the four limbs with globally preserved strength (grade V), without gait, static balance or sensory dysfunction. Eumetric and eudiadochokinetic. With no alterations in the assessment of the cranial nerves, but with signs of bilateral pyramidal release — cutaneous-plantar extension, presence of hyperreflexia and clonus. On inspection, eutrophic patient, atypical facies, bald and presented hyperpigmentation of the skin. He denied any type of previous sphincter alteration, as well as any other previous neurological symptoms. When actively questioned about his personal history and life habits, the patient also reported a history of having discovered an adrenal insufficiency in routine exams years ago, and that after extensive investigation and treatment with corticosteroids for months, without much improvement (sic), it was decided to interrupt the follow-up. Regarding alcohol consumption, he said to consume only socially. He denied frequent abuse or use of other drugs (licit or illicit). As for the family history, he said that years ago a brother was diagnosed with Guillain-Barré syndrome, and he has a nephew of the maternal family with a genetic neurological disease. He mentioned that his grandmother underwent genetic investigation, and it was discovered that she had the same disease. He denies any related prior personal investigation. Patient underwent laboratory and imaging investigation. Laboratory tests, including partial urine, serology, inflammatory and rheumatological tests, tumor markers, serum vitamin levels, thyroid function, kidney and liver functions, that were normal. Ultrasound of the kidneys and urinary tract was unchanged. Abdominal tomography showed only a small fecaloma in the rectal ampulla. Magnetic resonance imaging of the brain showed the presence of a slight increase in the periventricular white matter signal in the posterior portions of the brain parenchyma, affecting the bilateral occipital and parietal lobes on brain resonance. No significant degenerative or other changes in the spinal cord were seen on full-spine MRI. The cerebrospinal fluid analysis resulted in parameters within normal limits. Due to the suspicion of hereditary neurological pathology with a pattern of inheritance suggestive of X-linked disease, associated with adrenal insufficiency, a peroxisomal panel was used, which showed increased concentrations of C24:0 and C26:0 concentrations, and in C24/C22 and C26/C22 ratios (very long chain fatty acids), which confirmed the diagnosis of adrenomyeloneuropathy.