Showing papers on "Sandwich panel published in 1993"

Sandwich panel for angular forming

Abstract: A foldable composite panel (1) comprising an inner layer (2) formed from a first material having a relatively high plasticity at least in compression, bonded to at least one adjacent outer layer (3) formed from a second material having a relatively low plasticity. The composite panel (1) can be permanently folded without failure at ambient temperature through an angle substantially greater than that through which the outer layer (3) alone could be folded without failure under comparable conditions.

High temperature 2000 degrees-F burn-through resistant composite sandwich panel

Abstract: A composite sandwich panel structure having first and second honeycomb core layers and fire barrier membranes separating the honeycomb core layers as well as forming facing skins provides protection from burn-through after 15 minutes of subjection to a 2000° F. front side flame impingement at 10.5 btu/m 2 heat flux density, with a 110° F. average off-surface temperature 12" off of the backside of the panel. The facing skins on the outside of the honeycomb core layers are preferably formed by a layer of vermiculite film together with a layer phenolic prepreg. The center septum layer separating the first and second honeycomb core layers can be an inorganic fiber membrane, with a layer of phenolic prepreg on both sides thereof, and/or a layer of vermiculite film or other suitable materials providing a fire barrier. The honeycomb core layers are preferably made of a nylon paper honeycomb having a coating that itself forms a fire barrier, such as a coating of 80-96% sodium silicate, 1-4% vermiculite HTS and 2-15% H 2 O based phenolic resin.

Analysis of c-core sandwich plate decking

Abstract: Sandwich plate decking, consisting of two facing plates separated by a core of stiffeners, is known to possess high strength and high stiffness to weight ratios. This form of construction is appropriate for structures where the self weight is one of the governing design criteria. This is particularly applicable in the design of offshore accommodation modules to facilitate onshore or offshore installation. The self weight could be reduced while the strength is maintained. In this paper, the elastic constants for a C-core sandwich panel are summarized. In particular, the explicit expression representing the shear stiffness in the weaker direction is derived. Numerical examples are presented and the results obtained from thick plate bending analysis utilising these constants, are found to be in excellent agreement with the full 3-D finite element analysis. In comparison to the finite element analysis, the computation effort for the thick plate bending model is significantly smaller.

Process to mfr. sandwich panel with honeycomb core and convex surfaces - has sheet of thermoplastics on one side of core which is heated and drawn into cells by pneumatic pressure or suction

Abstract: A honeycomb core with parallel surfaces has a thin sheet (2) of thermoplastics material applied to one side. The sheet is heated and pneumatic pressure or suction is applied which form small cups in the sheet and are drawn into the cells (1.1) of the core (1). The workpiece is held on a worktable (5) and the upper surface is machined to the required contour. A sheet of thermoplastics material is then placed over the convex surface and the workpiece is placed on a worktable with a concave recess which matches the convex surface. The process is then repeated to produce a honeycomb core with two convex surfaces.

Honeycomb sandwich panel and manufacture thereof

Abstract: PURPOSE: To increase rigidity in a unilateral direction and attain a lightweight structure. CONSTITUTION: A honeycomb sandwich panel 1 has a honeycomb core 3 of aluminum, and surface plates 5a and 5b made of pasted fiber reinforced resin sheets such as a prepreg material having fiber arrayed in a span direction are arranged on both sides of the core 3, so that the fiber reinforced sheets are positioned at the side of the core 3. Then, the panel 1 is heated under pressure and integrated, using a hot press method, an autoclave or a vacuum bag method with vacuum. Also, fiber reinforced resin layers 4 are formed between the core 3 and the surface plates 5 and 5b in such state as arraying fiber in a unilateral direction. COPYRIGHT: (C)1995,JPO

Fire resistant sandwich panel

Abstract: A sandwich wall system panel (10,12) comprising an insulating core (18), a first metal skin (14) adhered to one face of the core, a second metal skin (16) adhered to the opposite face of the core, two separate elongate steel joining members (34,36), connected to the first or second skin and extending in parallel spaced relation to define a central joining tongue (33), first and second connectors (48,50) connecting the joining members of a pair, one at one end of the pair and the other at the other end of the pair, to prevent movement of the joining members towards and away from one another, the connectors being formed of expanded sheet steel, a steel grid or perforated steel sheet, said central joining tongue (33) being flanked by a pair of channels (35,37) and extending from the longitudinal edge of the panel, a pair of spaced parallel legs (24,26) formed by marginal portions of the first and second skins and projecting beyond the main insulating core at the opposite longitudinal edge of the panel, said legs being spaced to form a groove (32) to receive the tongue of an adjacent, similar panel, the legs being accommodated within the channels of the adjacent panel.

Insulating light transmitting flat structure panel providing the illusion of a three-dimensional array of step-like block structures, and method of constructing the same

Abstract: A novel "three-dimensional" appearing light-transmitting and insulating sandwich panel of planar outer facing sheets in which the illusion of a three-dimensional array of step-like block structures is produced by periodic light transmission contrasting blocks containing, internally of the panel, contrasting light-transmitting insulation filler battes in alternate blocks, and method of constructing the same.

The effects of long-duration space exposure on the mechanical properties of some carbon-reinforced resin matrix composites

Abstract: Long Duration Exposure Facility (LDEF) Experiment A0175 involved the non-instrumented exposure of seven carbon-fiber reinforced resin-matrix advanced composite panels contained in two trays - A7 and A1. These two trays were located, respectively, on the leading and trailing faces of LDEF, obliquely oriented to the RAM (Row 9) and WAKE (Row 3) directions. The identity and location of the seven panels, which consisted of six flat laminates of the following material systems are shown: carbon/epoxy (T300/934), carbon/bismaleimide (T300/F178), and carbon/polyimide (C6000/LARC-160 and C6000/PMR-15), plus one bonded honeycomb sandwich panel (T300/934 face sheets and Nomex core) patterned after the Space Shuttle payload bay door construction. These material systems were selected to represent a range of then-available matrix resins which, by virtue of their differing polymer chemistry, could conceivably exhibit differing susceptibility to the low-earth orbit (LEO) environment. The principal exposure conditions of the LDEF environment at these tray locations are shown. Noteworthy to some of the observations discussed is the four-orders-of magnitude difference in the atomic oxygen (AO) fluence, which made a shallow incidence angle (approximately 22 deg) to Tray A7, while Tray A1 on the trailing face was essentially shielded from AO exposure. This evaluation focused on determining the individual and relative suitability of a variety of resin-matrix composite systems for long-term space structural applications. This was accomplished primarily by measuring and comparing a range of engineering mechanical properties on over 300 test coupons sectioned from the flight panels and from identical control panels, and tested at ambient and elevated temperatures. This testing was supported by limited physical characterization, involving visual examination of flight panel surface features, measurements of weight loss and warpage, and examination for changes in internal integrity (micro cracking, delamination) by ultrasonic c-scan and polished cross-sections.

Fiber reinforced structures for turbine engine fragment containment

Abstract: This experimental research program tested two fibcr reinforced designs as lightweight containmcnt structures for turbine rotor disk failures. Thc first is a hybrid core sandwich panel capable of being used both as part of the airframe or nacclle structure and as a containment panel $necessary. Thc second is a collar or ring capable of being placed near the engine hot section. The hybrid sandwich panel is composed of a dry, unimpregnatcd fabric laminate core penetrated through its thickness by many rigid rods which connect the panel’s faccsheets. Shear, flexure and through-thickness compression tests showed that the panel’s strength and stiffness were comparable to typical honeycomb cored pancls. Spin chamber tri-hub rotor burst tests were performcd with a T-53 second stage power turbine failing in the tri-hub mode at 20,000 rpm. Three triangular structurcs formcd with flat panels and one lenticular structure formed with two curved panels were tested. These joined panel containment structures made with Kevlar 29 fabric and graphitelepoxy rods demonstrated the effectivcncss of the hybrid core to stop high velocity fragments. Ring structures were testcd to compare the performancc of Kevlar 29 with PBO (polybenzbisoxazole) fihcr. Thc room temperature containment performance of thc two fibers was found to be equivalcnt based on tri-huh rotor burst tests of cne PBO ring and one Kcvlar 29 ring with the same geometry and fibcr architecture. PBO has the advantage of temperature stability to 200°C and perhaps higher. The containment performance of Kevlar 29 rings with hoop/axial(0,90) reinforcement was compared to one with ?4Y reinforcement and results showed that a lowcr weight ring could bc designcd with the off-axis reinforcement but ring dcformation would be higher. ”

Mfg. sandwich plate - comprises wetting long sides of core only for glue bonding of cover plates to retain core strength

Abstract: For the manufacture of a sandwich panel, a core is formed from strips of fibre-containing material such as cardboard or paper, the breadthwise direction of which strips coincides with the thickness direction of the panel, and a covering sheet is subsequently bonded to each of the longitudinal sides of the core. In order to improve this bond, after the core is formed, at least one of its longitudinal sides is treated with a liquid for softening the edges of the strips at that side, following which the strips are exposed to a pressure force in the thickness direction of the panel, for upsetting each moistened edge, and an adhesive is applied to each edge thus upset, for the purpose of fixing a covering sheet thereon. The device used here comprises two moistening elements, together forming a nip through which the core can be conveyed, at such speed that sufficient moisture can be taken up for moistening the edges at the longitudinal sides of the core, while the central part of the core remains dry.

Sandwich panel of sheet metal

Abstract: This sandwich sheet metal comprises layers (16, 18, 20) of polymers inserted between two outer metal sheets (12, 14). Any two adjacent layers comprise polymers of different elasticity moduli. Layers of polymers of low elasticity modulus alternate with layers of polymers of high elasticity modulus. The layers (16, 18) adjacent to the outer metal sheets (12, 14) comprise a polymer of elasticity modulus lower than that of the polymer of the following layer (20).

Superplastic forming of sandwich panel

Abstract: A method for making a metallic sandwich panel, in which the cost of the forming dies is reduced relative to prior art methods, machining to adjust the sheet thickness of the face sheets after shaping is avoided, freedom in the design of the panel is made possible, and panels having smooth outer surfaces can be produced. According to the invention, a work piece (6) is formed by disposing a core sheet (1) between face sheets (2) and bonding the sheet (1) with the sheet (2) in a zig-zag pattern. Dummy sheets (4) are superposed on the outside of the face sheets (2), a fluid pressure is applied between the sheets (1 and 2) of the work piece (6) to shape the latter jointly with the dummy sheets (4), which sheets are effective to increase the deformation resistance and are removed after shaping. The dummy sheets serving to prevent creases or recesses in the facing sheets (2) during superplastic deformation.

Production of sandwich panel

Abstract: PURPOSE:To provide the process for production capable of producing the panel having a smooth outside surface at a low cost of metallic molds, etc., with a high degree of freedom in designing the panel without requiring the thick working of face sheets after molding. CONSTITUTION:A core sheet 1 is disposed between the face sheets 2 and the sheets 1, 2 are joined zigzag to each other to form a work 6. Dummy sheets 4 are superposed on the outer side of the face sheets 2 and the work 6 is molded by applying a fluid pressure between the sheets 1 and 2 of the work 6 at the time of molding such work 6. The dummy sheets 4, then, exhibit an effect of increasing deformation resistance and, therefore, the mold structure and device are simple and inexpensive and there is no need for thick working of the face sheets 2 after the molding. The degree of freedom in designing the panel is high and the panel and the smooth outside surface effective for beauty and performance is obtd.

Manufacture of sandwich panel

Abstract: PURPOSE:To ensure that the subject sandwich panel is highly light-permeable and manufactured at low cost by using a transparent surface sheet as either of an upper or a lower surface sheet which are attached to an upper and a lower opening in a main core body formed in a net pattern, and adhering this transparent surface sheet to the main core body in one piece using an adhesive of photocurable resin. CONSTITUTION:A honeycomb-shaped main core body 1 formed to a specified size is made of aluminum, paper, steel or resin as a material. Then an adhesive 3 of radiation- or photocurable resin is applied to an upper and a lower opening 1a. The adhered part 1a of one of the openings is placed on a surface sheet 2a, and further, a surface sheet 2b is placed on the adhered part 1a of the other opening. In this case, either of the surface sheets 2a, 2b is transparent. If an ultraviolet beam or a light is emitted to the surface sheet 2b which is transparent placed on the top, for example, the adhesive becomes cured and in turn, the adhered part 1a of the main core body 1 becomes conherent integrally with the surface sheet 2b.

Sandwiched aluminum panel

Abstract: PURPOSE:To improve the bending property and shock absorbability of a panel and also to raise productivity by composing a sandwich panel taking a network- like formed body as a core of integrally extruded materials. CONSTITUTION:An aluminum extruded material 18 having lateral plate parts 22 between belt-like longitudinal plate parts 20 of a prescribed width is made. Plural blanked open holes 24 are mutually zigzag formed on the lateral plate parts 22 having a shape that H-shapes are superimposed. When this is extended in the breadthwise direction while allowing expansion deformation in the longitudinal direction, parts where are not restrained with connecting parts 26 are bending or curving deformed, the open holes 24 are approximately hexagonally expanded and made into the network-like formed body 12 as a whole. By superposing brazing sheets 14, 16 of which the insides are cladded with a brazing filler metal on both sides of this network-like formed body 12 and brazing the end faces of each longitudinal wall part 20, the integral aluminum sandwich panel 10 is manufactured.

A simplified method for ultimate load prediction of all-steel sandwich panels

Abstract: This paper is concerned with the ultimate load prediction of a sandwich panel manufactured from a steel plate assembly. The panel essentially consists of two facing plates, spot welded onto a corrugated steel core. All the plates of a panel have identical thickness. Three groups of panels with varying plate thicknesses were examined. The typical panel considered in this study had plan dimensions of 2·1 m × 1·0 m with a core consisting of top-hat stiffeners of depth 60 mm, placed side by side. The panel was simply supported across its y-direction boundaries and subjected to uniform lateral loading over its entire surface. The plastic hinge theory is used to evaluate the ultimate collapse load of the panel. In this respect, two approaches are compared: one based on fullsection properties and the other based on the effective width concept. It is shown that the effective section gives more reliable collapse-load predictions than the full section. Theoretical collapse-load predictions agree very well with the experimental collapse load for a series of 13 panels. To accentuate the salient features of the technique, a numerical example is presented.

Thin stone-composite panel structure

Abstract: PURPOSE:To prevent the separation and falling-down of slab by a method in which a thin stone plate-bonded composite panel is combined with a holder to hold the two sides of the composite panel on a hold plate formed by laminating a metal sheet on the surface of a honeycomb core. CONSTITUTION:On a honeycomb sandwich panel formed by laminating a thin stainless steel plate on both sides of a honeycomb core as a hold plate 5, a thin stone plate 1 is bonded to the whole surface of the hole plate 5 by an epoxy resin adhesive to form a thin stone-composite panel. The composite panel is erected by turning its longitudinal direction vertically and the upside and downside of the panel are covered with holders 6 and 7 of a C-shaped cross section for aluminium sash, respectively. The panel is attached through the holders 6 and 7 to the base. The breakage and falling-down of the slab from the holders 6 and 7 can thus be prevented, and its deformation by loading can also be lessened.

Sandwich panel and method of manufacturing it

Abstract: Sheet metal sandwich consists of two outer metal sheets (12,14) between which is a polymer layer (16) loaded with spherical metal grains (18) that are lightly compressed between the sheets. The outer surface of the sheets are electroplated. The sandwich is made by coating one sheet (14) with liquid polymer (16) loaded with metal grains (18) larger than the liquid thickness and applying the second sheet under heat and press. to compress the grains. Pref. the polymer is polyurethane loaded at 5-25 wt.% with nickel grains of dia. D related to the final sheet (12,14) spacing E by 1.1E is less than D is less than 1.6E.

Sandwich structure member, shielding performance, sandwich panel and sandwich structure having excellent sound insulation performance and electromagnetic

Abstract: PURPOSE:To improve noise insulation effect and to shield from electromagnetic wave by restraining coincidence effect, resonance of hard boards and transmission of solid noise by applying ferromagnetic alloy as a hard board of a sandwich structure member. CONSTITUTION:In a sandwich structure member which is comprised of a pair of hard plane boards 2, 3 whose surfaces are made parallel each other and a core material 1 by an elastic material, a viscoelastic material or a porous material inserted to an air layer 4 in an intermediate thereof, at least one of a pair of hard boards 2, 3 is formed of ferromagnetic alloy.

Packaging, deployment, and panel design concepts for a truss-stiffened 7-panel precision deployable reflector with feed boom

Abstract: A concept is presented for achieving a remotely deployable truss-stiffened reflector consisting of seven integrated sandwich panels that form the reflective surface, and an integrated feed boom. The concept has potential for meeting aperture size and surface precision requirements for some high-frequency microwave remote sensing applications. The packaged reflector/feed boom configuration is a self-contained unit that can be conveniently attached to a spacecraft bus. The package has a cylindrical envelope compatible with typical launch vehicle shrouds. Dynamic behavior of a deployed configuration having a 216-inch focal length and consisting of 80-inch-diameter, two-inch-thick panels is examined through finite-element analysis. Results show that the feed boom and spacecraft bus can have a large impact on the fundamental frequency of the deployed configuration. Two candidate rib-stiffened sandwich panel configurations for this application are described, and analytical results for panel mass and stiffness are presented. Results show that the addition of only a few rib stiffeners, if sufficiently deep, can efficiently improve sandwich panel stiffness.

Mechanical properties of honeycomb prepared from aromatic polyimide film

Abstract: Aromatic polyimides have many advantages such as low thermal expansion coefficient, good electrical insulation, and self-extinguishing properties. We tried to use polyimide film for honeycomb structure. Polymide honeycomb core and sandwich panel were prepared from polyimide film, i.e., UPILEX R, and adhesive by the expansion method. Mechanical properties, i.e., compressive, crushed, shear, and flexural strengths, were evaluated for this core and panel. Compressive and crushed properties increased largely with the density of the honeycomb, whereas shear and midspan flexural properties did not vary so much with the density, because these failures occured in the adhered interface. Strong adhesion is required for improving the latter properties. © 1993 John Wiley & Sons, Inc.

Sandwich panel of honeycomb structure - has additional layer inserted between honeycomb core and thermoplastics outer layer

Abstract: A sandwich panel consists of a honeycomb core (1) which is covered with a sheet (2) of thermoplastics material. This is assembled by a positive pneumatic pressure or by suction. An additional layer (4) of material is inserted between the honeycomb core (1) and the thermoplastics sheet (2). This additional layer is in the form of a grid and has a thickness which is considerably greater than the thickness of the thermoplastics sheet (2). USE/ADVANTAGE - Is more easily manufactured than existing types.

Shells of Sandwich Construction

Abstract: Sandwich construction, like the name implies, usually consists of two faces which are kept separated by a core. The facings usually carry the in-plane primary loads (tensile, compressive, and in-plane shear), while the core (analogous to the web of an I-beam) resists the transverse shear loads. The two faces usually are composed of the same material, and have the same thickness (tf), which places the neutral surface of bending at the mid-plane of the sandwich cross-section, as shown in Figure 24.1 (a).

Lightweight sandwich panel

Abstract: Disclosed is a lightweight sandwich panel with two skin layers (1, 2) and a core layer. The core layer is between the skin layers and firmly attached to them. It is proposed that the core layer should be formed from parallel hollow plant stems (3) fixed perpendicularly to the skin layers.