Showing papers on "Sandwich panel published in 1990"

Lightweight sandwich panel

Abstract: A very lightweight sandwich panel is constructed using as the core layer a very thin plastic sheet that has been preformed with projections having broad bonding areas on their free ends for chemically cementing to one outer layer of the panel and with areas between the projections for bonding to the other outer layer. The projections may be made of different cross-sectional shapes, heights, spacings, tilts, profiles, etc., to produce different characteristics in the panel. Differences may even be made in a given sheet to produce a panel having different characteristics in various portions, including shape and function. These characteristics can be predetermined, and the panels may therefore be computer designed. Special panel applications such as airplane wings and thermal boards are comtemplated.

Apparatus to attach a sandwich panel

Abstract: An apparatus for attaching a sandwich panel to another structure. A hollow pin passes through the panel near the edge to be joined to the structure. A bolt, passing through the edge of the panel, and barrel nut, inside the hollow of the pin, are used to draw the edge of the panel against a flange attached to the structure. The panel may be reinforced with doublers or an end cap.

Core arrangement in mineral wool sandwich panel

Abstract: A sandwich panel element comprises a core of fibrous material arranged between first and second parallel outer skins of generally planar sheet material. The core material consists of a plurality of elongate strips arranged in side-by-side and end-to-end abutting relationship. The strips are formed so that the fibers are in a direction generally transverse to the planes of the sheet material. The strips are individually shorter than the length or width of the panel element and the mutually abutting ends of the strips are staggered with respect to rows of adjacent strips. The ends also may be chamfered at an acute angle to the longitudinal direction of the strips to allow the ends to overlap.

The effective boundary conditions for a perforated elastic sandwich panel in a compressible fluid

Abstract: The transmission of sound through a sandwich panel, consisting of a honeycomb cellular structure bounded by two thin elastic plates, is considerably reduced at a certain frequency if one (or both) of the plates is perforated so as to link a significant number of the cells to the exterior fluid. This effect occurs at or near the Helmholtz resonance frequency for the cells, with the acoustic wavelength large compared with the cell dimensions. An analysis is given for the problem of plane waves incident upon a plane sandwich plate of infinite extent, using matched expansions, for the cases of acoustically hard or acoustically transparent cell walls. The compound panel is shown to be acoustically equivalent to that of a hypothetical surface with different normal velocities on either side and effective boundary conditions are derived, with generalizations to deal with more complicated structures, finite plates and more general incident fields.

Pre- and postbuckling finite element analysis of curved composite and sandwich panels

Abstract: A three-dimensional degenerated isoparametric multilayer finite element is described in conjunction with an automatic incremental/iterative method to find the complete nonlinear response of arbitrarily laminated composite and sandwich panels under destabilizing loads. The case of thick sandwich panels is investigated by comparing three different models: 1) a high-order, multilayer shell element, 2) a multilayer shell element with null transverse shear moduli in the skins layers, and 3) a superposition of multilayer isoparametric membranes for the skins, and a volume element for the core. All these models allow the accurate representation of the cross-section warping in thick shear deformable sandwich panels and, after some validation tests, the model (3) is found to be the most efficient. In the prebuckling range of the structural response, incremental bifurcation analyses are combined with an arc-length algorithm to control the step size; for the postbuckling path, the increment size is determined automatically by a new recurrence formula. The good behavior of this proposed procedure is illustrated on two structural postbuckling applications, namely, a highly curved cylindrical composite panel and a sandwich panel with flange edges both subjected to in-plane compression.

Scattering by a Semi-Infinite Sandwich Panel Perforated on One Side

Abstract: The scattering of sound waves by the edge of a sandwich panel which consists of two thin elastic plates containing a light interior cellular structure is analysed. The Wiener-Hopf method is used to examine the interaction effects of a semi-infinite panel clamped to a semi-infinite rigid screen. One major difficulty is that the presence of two different velocity potentials on either side of the plane y = 0, results in a matrix Wiener-Hopf equation. An approximate solution is given in the asymptotic limit of small values of a parameter $\tau $, which accounts for the perforations.

Sandwich panel core structure

Abstract: A sandwich panel element comprises a core 10 of fibrous material arranged between first and second parallel outer skins of generally planar sheet material 30, 32. The core material consists of a plurality of elongate strips 12a, 12b, 12c etc. arranged in side-by-side and end-to-end abutting relationship. The strips are formed so that the fibres are in a direction generally transverse to the planes of the sheet material 30, 32. The strips 12a, 12b, 12c etc. are individually shorter than the length or width of the panel element and the mutually abutting ends 25 of the strip are chamfered at an acute angle to the longitudinal direction of the strips to allow the ends to overlap.

Sandwich panel material, and a method of providing a local reinforcement in a sandwich structure

Abstract: The invention is directed to a sheet-like sandwich material provided with a local reinforcement, comprising a core material sandwiched between two reinforced top layers, which core material is a thermoplastic, foamed core material or a core material having a honeycomb structure, and which top layers consist of a thermoplastic synthetic plastics material reinforced with fibres, preferably in the form of a woven fabric, a knitted fabric, a fibrous web, or unidirectionally applied fibres, and at least one local reinforcement consisting of an amount of plastic material injected under pressure into the core material through one of the top layers, and which plastic material has hardened after injection and to a process for providing local reinforcement in a sheet-like sandwich material.

Sandwich panel cutting method and machine tool

Abstract: A method and apparatus for cutting a workpiece, such as a panel, in particular a sandwich panel, in which an elongate milling cutter 21 is mounted in axially spaced bearings 18, 19. A workpiece is supported on a support 11 and a relative cutting sweep movement between the supported workpiece and the elongate cutter is caused to take place in at least one direction transverse to the axis of the cutter, whereby the cut is made in that transverse direction.

Sandwich panel using core, only edge face of which resin adheres to

Abstract: PURPOSE:To reduce a resin quantity of an adhesive agent by maintaining strength, by a method wherein a honeycomb sandwich panel for which a honeycomb core is used is formed by sticking fillet-formable resin to end faces of both sides of the core. CONSTITUTION:A sandwich panel is formed by making use of a honeycomb core (d) by sticking fillet-formable resin to only end faces of both sides of the honeycomb core, suitably at a quantity of 20-120g/m per one side. A fillet 1 where a, length ratio between a width (a) and teight (b) of the base is 1 versus 0.2-5 is favorable one. Especially the fillet 1 whose sectional curve (c) becomes a temple-bell-like curve is far suitable from an economical point of view. Resin whose viscosity and flow capacity index are respectively 3-3000 poises and 2-60 at a fixed fillet making temperature is suitable for fillet forming resin.

Manufacture of metallic sandwich panel

Abstract: PURPOSE:To obtain a metallic sandwich panel having smooth surfaces by joining face sheet materials and a core material small in deformation resistance meanderingly and forming the face materials and core material heated at a prescribed temperature as the spaces between them are charged with fluid pressure. CONSTITUTION:The core material 1 small in deformation resistance is arranged between the face sheets 2a, 2b to join the joined parts 3 meanderingly. When the spaces between the above face sheet materials 2a, 2b heated at the prescribed temperature and the core material 1 are charged with fluid pressure P, the core material shows superplastic flow at a prescribed forming temperature and since the deformation resistance is drastically small to the face sheet material, the core material only is deformed to perform prescribed forming. The deformation of the face sheet materials is so small in the above forming that wrinkles are not generated on the surfaces of the metallic sandwich panel. In this way, the metallic sandwich panel having smooth surfaces can be obtained and also, out-of-plane flexural rigidity of the panel is improved and structural properties can be obtained in accordance with the design.

Double thin stone-laminated composite panel

Abstract: PURPOSE: To reduce the weight of a compound panel, and to improve the workability by attaching thin layer stones to both surfaces of a sandwich panel formed by laminating a honeycomb core having the predetermined cell size and the predetermined core foil thickness and skins and adhering them to each other. CONSTITUTION: Relation between the cell size [X mm] of a honeycomb core 4 formed of hexagonal cells 5 formed by using the phenol resin included craft paper and thickness [y mm] of a core foil of the honeycomb core 4 are expressed with a formula (x/y) 400. A skin 6 formed of a stainless steel thin plate is laminated on both surfaces of the honeycomb core 4 by the epoxy adhesive agent so as to form a sandwich panel 2. A thin stone layer of granite 1 is adhered to both surfaces of the sandwich panel 2 by the epoxy adhesive agent 3. With this structure, a light compound panel having excellent workability and effective design is obtained.

Core for sandwich panel, only to edge face of which resin is adhered

Abstract: PURPOSE:To decrease the quantity of resin as adhesive by a method wherein the quantity of the fillet formable resin lying within the specified range per one side of a core is adhered only to the edge face at both the front and rear sides of the core CONSTITUTION:Only to the edge face at both the front and rear sides of a sandwich core, 5-150g/m per one side of fillet formable resin is adhered The fillet formable resin is organic adhesive, which exhibits fillet forming power during the bonding between the core ad surface material and epoxy-based, unsaturated polyester-based, polyurethane-based, polyamide-based adhesives and the like are exampled for cold-setting adhesive and thermosetting adhesive and, further, ethylene-polyvinyl chloride copolymer-based, butadiene-based, polyamide-based, polysulfone-based adhesives and the like are exampled for thermoplastic adhesive They are used singly or in the form of the mixture prepared by blending one or more of them with one another As a result, in case that a sandwich panel is produced through the bonding between skin and the adhesive, favorable fillets can be formed at the bonded part between the core and the skin

Preparation of lightweight honeycomb sandwich panel

Abstract: PURPOSE:To prevent the generation of the dimple of a carbon fiber reinforced plastic(CFRP) skin after sandwich molding and to prevent a lowering of rigidity as a sandwich panel by applying tension to the CFRP skin before sandwich molding is performed under heating. CONSTITUTION:A CFRP skin 1a to which tension is applied by a tension jig 10a and an aluminum honeycomb core 2 coated with an adhesive 3 made of an uncured thermosetting resin are placed on the plate 16 of a molding stand 5 and a slippage preventing frame body 7 is arranged. A CFRP skin 1b to which tension is applied by a tension jig 10b is laminated to the core 2 and a plate 6 is placed thereon and the whole is covered with an airtight sheet 8 to be evacuated. When the whole is pressed and heated, the adhesives 3 between the honeycomb core 2 and the CFRP skins 1a, 1b are reacted and the CFRP skins 7a, 1b are bonded to the honeycomb core 2 in such a shape that cells 2a are expanded. Since tension is applied to the CFRP skins 1a, 1b, the contraction of the cells 2a of the honeycomb core 2 is suppressed and the dimples of the CFRP skins 1a, 1b are not generated.

Sandwich panel and connecting construction thereof

Abstract: PURPOSE: To improve watertightness by providing a tapering fitting projected part having a locking part on one end and a fitting recessed part having a part to be locked on the other end of a panel filled with heat insulating material inside it, and mounting packing material on the bottom of the recessed part CONSTITUTION: A tapering fitting projected part 4 having a locking part 6 is provided on one end of a panel main body A filled with heat insulating material 2 between both sides of a skin 1, and a fitting recessed part 5 having a part 7 to be locked is provided on the other end Packing material 8 is mounted on the bottom of the fitting recessed part 5 The fitting projected part 4 is inserted to the fitting recessed part 5 of an adjoining panel, and the extreme end is pressed against the packing material 8 and fixedly secured Hereby, mounting of the panel A is facilitated and invasion of rain water can be prevented COPYRIGHT: (C)1992,JPO&Japio

The acoustic transmission properties of anisotropic sandwich panels with perforations

Abstract: A rectangular sandwich panel, consisting of two thin plane shells on either side of a cellular structure, has perforations in one of the bounding shells so that some or all of the cells may act as Helmholtz resonators. The compound panel is set in an otherwise rigid plane baffle and is irradiated by a plane wave travelling from the unperforated side of the system. An estimate is presented, in integral form, for the acoustic power transmitted through the panel, averaged with respect to time and with respect to all possible directions of incidence, in the limit of large values of ka and kb , where k is the acoustic wavenumber and a , b denote the plate dimensions. For operating frequencies below a certain critical coincidence value, the basic estimate is supplemented by an additional contribution from the resonantly driven but acoustically inefficient modes, which become significant at modest values of ka and kb if the mechanical loss factor ϵ is sufficiently small. There is good agreement between the numerical evaluation of the estimates and the available experimental data.

Honeycomb surface plate

Abstract: PURPOSE:To obtain a lightweight honeycomb surface plate and facilitate shift by making the upper surface plates from oxide group ceramics, among the surface plates joined onto the upper and lower cell edge surfaces of a honeycomb core and covering the surface plate by a metallizing film made of hard ceramics. CONSTITUTION:A honeycomb surface plate has a honeycomb core 2 as core member and has a sandwich panel form in which surface plates 3 and 4 are joined onto the upper and lower surfaces. The upper side surface plate 3 is made of oxide group ceramics, and covered by a metallizing film 5 made of hard ceramics. Therefore, the honeycomb surface plate is made lightweight, and heat resistance, erosion resistance, abrasion resistance, rigidity, and strength can be improved, and surface precision can be improved.

Local reinforcement of sandwich panel member and sandwich structure

Abstract: PURPOSE: To provide a local reinforcement in a sheet-like sandwich material in a short time by comprising at least one local reinforcement consisting of a plastic material injected and hardened under pressure into a core material through one of the top layers, and injecting an amount of plastic material under pressure through one of the top layers into the core material. CONSTITUTION: A sheet-like material (sandwich structure) to be reinforced can be made by laminating each component to be used, i.e., foam core and top layers, with bonding layers between them, and with or without the use of softening agents, and subsequently bonding the layers together by applying heat and pressure. When an injection molding machine is used, a nozzle is moved to the place to be reinforced to inject a metered dose of molten thermoplastic synthetic resin. Owing to the force of the injection, the plastic material is injected through the top layer and finds its way into the core. Depending on the conditions and materials used, this will take place through displacement and/or fusion. When used in thermoplastic sandwich structure, this has great advantages, as the heat of the molten thermoplastic synthetic resin being injected causes the foam to melt during its injection into the core of the sandwich structure. There is obtained a good bonding of the local reinforcement in the core to the top layers.

Structural response of marine sandwich panels to uniform pressure loading.

Abstract: : Deflection and strain responses of six marine sandwich panels to uniform pressure loading are investigated. Panels are full scale typical of those found in a 40' high performance deep-vee monohull. Three combinations of matrix-reinforcement are used in the panel faces: bi-axial (0 deg - 90 deg) E- glass in a fire retardent vinyl ester resin (DERAKANE 510A), bi-axial and double bias (+ or - 45 deg) Kevlar in DERAKANE 510A, and bi-axial and double bias Kevlar with an elastomer modified vinyl ester resin (DERAKANE 8084). Polyvinyl chloride foam AIREX is the core material. A panel test mechanism applies uniform pressure to panels 90 in. wide by 120 in. long. The central test section is 30 by 60 in. and is isolated by one panel span to simulate in situ boundary conditions. Two pressure loading rates (static and cyclic) are employed allowing examination of viscoelastic effects. A material and mechanical characterization of the sandwich panel lower faces is conducted. Membrane behavior is not evident on a per cycle basis, yet its effect can be seen over successive cycles. The non-linearity and hysteresis diminish with repeated loading. After relatively few cycles, the deflection and strain responses become linear, the rate- normalized bending stiffness lessens, and the overall panel response approaches that recorded during static tests.

Production of sandwich panel

Abstract: PURPOSE:To produce a lightweight sandwich having few voids in the core and a good product appearance by pouring a rigid urethane foam composition containing a specified catalyst into between facings and foaming the composition. CONSTITUTION:A process for producing a sandwich panel by pouring a rigid urethane foam composition based on a polyisocyanate, a polyol, a blowing agent and a catalyst into between facings and foaming the composition, wherein a quat. salt (A) of 1,8-diazabicyclo(5,4,0)undecene-7 and bis(2-dimethylaminoethyl) ether (B) are used as the catalyst. It is desirable that the ratio of compound A to compound B is desirably 90:10-50:50 and that the amine polyol is used in an amount of at least 25wt.% based on the total polyol. According to the above, a lightweight sandwich panel having few voids in the core and a good product appearance can be produced.

Truss-core sandwich design via PANDA2

Abstract: The computer program PANDA2 for minimum weight design of composite, stiffened cylindrical or flat panels made of composite material is described. The capability of PANDA2 has been expanded to handle truss-core sandwich panels. The new capability is demonstrated in this paper with an example: minimum weight design of a truss-core sandwich panel under axial compression, in-plane shear, and normal pressure. At the design load the panel is in a locally postbuckled state.

Fireproof joint structure for wall

Abstract: PURPOSE:To form a wall body abundant in fireproofness by fixing a reverse T-shaped panel strip on a building frame, providing a sandwich panel on the side of the vertical section of the panel strip, and providing a fireproof joint material between the panel side end and the vertical section of the panel strip. CONSTITUTION:A sandwich panel 1 integrally formed with front and back materials made of a metal thin plate and a core material made of lock wool and provided with a fireproof packing material 14 on the side is brought into contact with a panel strip 12 and fixed to a building frame 11 with bolts 26. An elastic and adhesive fireproof joint material 13 is filled, and a fitting metal 15 is fixed to a surface material with rivets 27. A cover 20 is coupled to cover a joint section 24. A weather-resistant wall body in which no mite or mildew is generated can be formed.

Honeycomb core of sandwich panel

Abstract: PURPOSE:To obtain a sandwich panel which is superior in corrosion resistance with electromagnetic wave shielding properties and, easy to form, by constituting said panel of a base material obtained by laminating a non-metallic sheet material onto both surfaces of a plate-like metal material which has electromagnetic wave shielding properties at cell walls thereof, and connecting said cell walls by a conductive cover passing through said base material. CONSTITUTION:A craft paper 6 is laminated on both surfaces of a preformed band-shaped copper foil 5, thereby to obtain a base material 4. The base material 4 is processed in advance into a corrugated shape so that alternate protruding and recessed portions continuously form trapezoids. A predetermined number of this base material 4 are senquentially arranged in such a manner that connecting portions 7 thereof are positioned in abutment with each other, and bonded by an adhesive agent 8. A conductive cover 10 has a length approximately equal to the length W in a laminating direction of a honeycomb core 1, passing through approximately at the center of the connected connecting portions 7 of the base materials 4 forming cell walls 2 along the laminating direction W. Moreover, the cover 10 is held in contact with the copper foils 5 of the base materials 4.