Showing papers on "Sandwich panel published in 1994"

A new structurally and thermally efficient precast sandwich panel system

Abstract: A new precast concrete sandwich panel system with a high thermal resistance and optimum structural performance has been developed. A hybrid truss provides the connector in this panel system - the diagonals are fiber-reinforced plastic bars and the chords are prestressed steel strands. Each connector consists of a fiber-reinforced plastic bar fabricated in a deformed spiral shape through which a pair of prestressing strands is threaded to provide anchorage in the concrete wythes. The developed shear connecting system is described together with its advantages. An experimental and analytical investigation of the connecting system was conducted. The experimental program included testing of small scale specimens by push-off loading, small scale panels by flexural loading. The analytical investigation included finite element modeling of the tested small scale specimens and comparisons with theory of elasticity solutions. Experimental and analytical results from finite element modeling and from theory of elasticity equations correlated well and showed that the developed panel system meets the objectives of the research and is expected to have a promising future.

Flexural behavior of composite precast concrete sandwich panels with continuous truss connectors

Abstract: Two series of composite precast concrete sandwich panel (PCSP) systems containing various connector reinforcement and construction details were tested in flexure. Panels of one series utilized details similar to certain commercially produced panels, while the second series panels contained modified details to better evaluate interface shear transfer behavior. Results of static testing indicated that a high degree of composite stiffness and composite flexural capacity can be attained with truss girder connectors oriented longitudinally in the panels. Test results also showed that construction details can have a significant impact on the distribution of shear in elements crossing the interface. Results of fatigue testing indicated relatively minor stiffness loss over 55,000 loading cycles.

Elastic Constants for Z‐Core Sandwich Panels

Abstract: The computational effort to analyze a sandwich panel can be greatly reduced if an equivalent 2D thick-plate bending model is used instead of a detailed 3D finite-element model. The success of the transformation from a sandwich panel to a 2D thick-plate bending model depends on the equivalent elastic constants used. In this note, these elastic constants for Z-core sandwich panels are summarized. The elastic constant for the shear stiffness in the weaker direction for Z-core sandwich panels is derived. To ascertain the validity of the elastic constants, the results obtained from the 2D thick-plate bending model with different boundary conditions are compared with a detailed 3D finite-element model. From the results, it is shown that excellent agreement is obtained between the two models.

Building panel, manufacturing method and panel assembly system

Abstract: The improved sandwich panel of the present invention includes inner and outer panel faces that have a foam core integrally bonded therebetween by the hardening and curing of a liquid foam during the manufacturing process. The faces of the preferred panel embodiments are composed of cement-fiber boards and/or cement-woodchip boards. The preferred sandwich panel has a male projecting lateral edge on one side and a female recess in the core on the opposite side edge. The preferred method of manufacturing the panels includes the installation of the male edge member prior to foaming and the utilization of edge recess forming members installed at the edges of the panel assembly prior to the insertion of liquid foam therebetween. The removal of the edge recess forming members following the curing of the foam easily creates the edge recesses. The method of construction of a structure utilizing the improved panel includes the installation of a bottom sill to a foundation or floor, the engagement of panel members to the bottom sill and to each other through the male-female side edge interconnection and the placement of a continuous top plate within the top edge recesses of the panels. Thereafter, by nailing, the assembled panels are engaged to the bottom sill, to each other through the male-female interconnection and the top sill.

Fiberglass sandwich panel

Abstract: A roofing system that provides a safe, long lasting, leak-free and maintenance-free insulated roof for flat roof applications. More particularly, a sandwich panel comprises an inner foam core, a fiberglass skin fully encapsulating and surrounding the core, and a gel coating surrounding the skin. The panel has two substantially parallel surfaces and a peripheral edge having a step edge. A plurality of panels having two different shapes and relative dimensions are alternately secured to purlins to form the roofing system so that half of the panels can be easily removed without affecting the rest of the roof.

Hybrid honeycomb sandwich panel

Abstract: A combination of a thin upper honeycomb core plus a lower honeycomb core of equal or lower density than the upper core united by only a thin light weight interlayer within two outer skins provides a low weight hybrid panel with increased durability when the upper surface is subjected to localized compressive loads

Large-strain 3D-analysis of fibre-reinforced composites using rebar elements: hyperelastic formulations for cords

Abstract: The well-known finite element representation of reinforcing bars by means of overlay (“rebar”) elements is recast in the context of finite strain analyses of cord-reinforced composite materials. The variational formulation including the linearized forms is presented on the basis of hyperelasticity. Three material laws including two variants of the Neo-Hooekean model and the quadratic logarithmic model are investigated. An explicit formulation for uniaxial stress states is given for the Neo-Hooekean model. A comparative evaluation with regards to computational efficiency and physical plausibility shows that the logarithmic model is optimally suited for this class of problems and for moderately large strains. The rebar-element concept in conjunction with an incompressible finite element formulation for the representation of a rubber matrix material is applied to comparative finite strain FE-analyses of a cord-reinforced rubber sandwich panel, with different hyperelastic models used for modelling of the ply material.

Thermoelastic Formulation of Stiffened, Unsymmetric Composite Panels for Finite Element Analysis of High Speed Aircraft

Abstract: An emerging technology need for capturing 3-D panel thermoelastic response with 2-D planar finite element models (FEMs) is aided with an equivalent plate stiffness and thermal coefficient formulation. The formulation is general and applies to all material types and stiffened and sandwich panel concepts. Included with the formulation is the ability to provide membrane-bending coupling of unsymmetric sections and calculation of all thermal expansion and bending responses from in-plane and through-the-thickness temperature gradients. Thermal residual strains for both the laminates and plies are included. The general formulation is defined and then applied to a hat- shaped, corrugated stiffened, metal matrix, fiber-reinforced composite panel. Additional formulations are presented where required to include all of the hat''s unique characteristics caused by the cell shear flow in the closed section such as the in-plane shear and bending-twisting response. Each formulation is validated independently with 3-D FEA.

A method of fabricating a composite material part, in particular a sandwich panel, from a plurality of assembled-together preforms

Abstract: Distinct preforms are made for different portions of a composite material part that is to be fabricated, and they are assembled together in a non-densified state or in a state that is not completely densified by bonding respective contacting surfaces of the preforms (13, 15, 36) together by means of fibrils (17, 19) projecting perpendicularly from the surface of one of the preforms (13, 15) and in which the surface of another preform (36) is engaged. The assembled-together preforms are then co-densified. The fibrils are formed on the surface of a fiber preform by the ends of fibers thereof that have been displaced by the preform being needled. The method is particularly suitable for fabricating a sandwich panel of composite material comprising two rigid skins between which there is disposed a core constituted by partitions that are perpendicular to the skins.

Near-surface enhancement of honeycomb sandwich structures to improve durability using a foaming adhesive

Abstract: A honeycomb sandwich panel is modified by the controlled incursion of a foaming adhesive (2) into the upper region of the honeycomb. This provides a panel having increased durability when the upper surface (17) is subjected to localized compressive loads.

Process for the production of a workpiece made of composite material, especially a sandwich panel, from several preforms assembled together

Abstract: Separate preforms are produced for different parts of an article, made of composite material to be manufactured, and are assembled in an undensified or incompletely densified state, by bonding between the corresponding contact surfaces of the preforms (13, 15, 36) by means of fibrils (17, 19) which project perpendicularly to the surface of a preform (13, 15) and into which the surface of another preform (36) fits. The assembled preforms are then densified together. The fibrils are formed at the surface of a fibrous preform by the fibre ends of the latter which are displaced by needling the preform. The process is suitable in particular for the manufacture of a sandwich panel made of composite material comprising two rigid skins between which is arranged a core made of partitions which are perpendicular to the skins.

Evaluation of Commercial Wood-Cement Composites for Sandwich-Panel Facing

Abstract: Within the general framework of developing a cement‐based sandwich panel for housing construction, wood‐cement composites were identified as a promising facing material. Five commercially available wood‐cement and natural‐fiber‐cement board products were studied in an experimental program. The modulus of elasticity, the limit of proportionality stress, the modulus of rupture, and the post‐cracking behavior were measured in three‐point bending. The compressive strength and failure mode were characterized from uniaxial compression tests on small cubic specimens. The microstructure of these composites was characterized using a scanning electron microscope. The effect of the fiber reinforcement on the mechanical properties was related to the observed behavior.

Manufacture of brazed sandwich panel and jig for manufacturing

Abstract: PURPOSE:To easily manufacture the brazed sandwich panel having the desired curved surface without decreasing strength. CONSTITUTION:The honeycomb panel is press-formed by using a couple of upper mold 2 and lower mold 4 constituted of forming parts 2a and 4a formed in a two-dimensional curved surface shape where a couple of facing surfaces conformable mutually are made to the forming surfaces, respectively and grid- shaped reinforcing parts 2b and 4b provided on the opposite sides to the forming surfaces of the respective forming parts 2a and 4a. The upper mold 2 and the lower mold 4 are made of the same material as the panel so as to attain the same coefficient of expansion as the honeycomb panel. Consequently, the honeycomb panel having the two-dimensional or three-dimensional curved surface can be easily manufactured without decreasing strength.

Sandwich panel with reinforced connecting holes and method for making it

Abstract: The intention is to provide a sandwich panel, comprising at least two metallic outer sheets 5, 7 and an intermediate layer 14, with a connecting hole running substantially transversely to the plane of the panel. This is performed by the hole having a thin-walled grommet in the form of a sleeve 8 which is sealed with respect to the intermediate layer and merges seamlessly with the outer layers 5, 7 of the sandwich panel 2. In a method for making connecting holes in a sandwich panel which comprises at least two metallic outer sheets and an intermediate layer, the connecting holes running substantially transversely to the plane of the panel, the connecting holes are produced by flow-boring into the sandwich panel from one side of the panel, a sleeve 8 being formed in the circumferential region of each connecting hole from the outer sheets 5, 7, which sleeve seals the connecting hole with respect to the intermediate layer 14 of the sandwich panel 2.

High-order bending of sandwich panels with a transversely flexible core

Abstract: A general, high-order theory for the bending behavior of a sandwich panel with a "soft" core, i.e. flexible in the vertical direction, based on variational principles is presented. The theory embodies a general rigorous and systematic approach to the analysis of plates having high-order effects owing to the non-linear patterns of the longitudinal, the transverse and the vertical deformations of the core through its height. As such it improves on the available classical and high-order theories. The formulation details the governing equations and the associated boundary conditions. Panel construction consists of upper and lower skin, metallic or composite laminated symmetric, with non-identical mechanical and geometrical properties and a "soft" core made of foam or aramid honeycomb. The formulation uses a classical plate theory for the skins and a three-dimensional elasticity theory for the core. The behavior is presented in terms of internal resultants and displacements in skins, peeling and shear stresses in skin-core interfaces, and stress and displacement fields in the core, even in the vicinity of concentrated loads. The analysis is applicable to any type of loading, distributed or concentrated, and it distinguishes between loads applied at the upper or at the lower skin. It deals with any type of boundary conditions including different conditions at the same section for the upper and the lower skins since these conditions are separately hlfilled for each skin-panel at a specified section. A simply-supported panel subjected to uniformly distributed and a concentrated load with identical skins is studied analytically and numerically.

Adhesive jig and manufacture thereof

Abstract: PURPOSE: To provide an adhesive jig in which first high accuracy and high reliability of accurately adhering a replacing part are provided in the case of partly replacing the defective part of a honeycomb sandwich panel in which both the outer surfaces are bent, second simple and easy manufacture and preparation can be provided with low cost and third the manufacture and the preparation can be performed in a short time, and a method for manufacturing the same. CONSTITUTION: A pair of upper and lower adhesive jigs 7, 8 have curves corresponding to the outer surfaces of a honeycomb sandwich panel 1 to be replaced, and a honeycomb core 13 having an inner surface 11 in inner contact with the outer surface, a buckling part 14 capable of buckling corresponding to the curve of the outer surface or the uneven part in pressure contact with the outer surface of the above surface 11, and a flat outer surface 12. The core 13 is turned to the outer surface of the panel 1 before replacing to be replaced and pressed to be manufactured for preparation.

Production of honeycomb sandwich panel

Abstract: PURPOSE:To effectively prevent that a resin defect part is generated in a lower surface plate in a honeycomb sandwich panel having upper and lower surface plates using a resin whose lowest viscosity at the time of heating is a specific value or less. CONSTITUTION:In the production of a honeycomb sandwich panel 1 using a prepreg 2a for upper and lower surface plates using a resin whose lowest viscosity at the time of heating is 50 poise or less, a honeycomb member 4 is laminated on the prepreg 2a for the lower surface plate through a resin film 3a and the prepreg 5a for the upper surface plate is laminated on the core member 4 and, thereafter, the whole is heated to predetermined temp. for a definite time while degassed under vacuum. After vacuum degassing is released, temp. is further raised to perform molding under pressure and heating.

Box-shaped object using sandwich-panel

Abstract: PURPOSE:To propose a box-shaped object using sandwich-panels with a view to firstly simplifying the assembly work, freeing the procedure from troublesome steps, and reducing the working steps involved; secondly, achieving ease especially in the positioning; thirdly, reducing the work considerably with respect to waterproofing by application of an adhesive or sealant or the like and with respect to fixation by riveting; and, fourthly, in view of conspicuousness of these advantages especially in the case of a large-scale structure; and furthermore to propose a box-shaped object of the same type for which, fifthly, the work of waterproofing is not required in the assembling. CONSTITUTION:A set of corner materials 7 for each corner consists of a pair of molded members 4, 5 joined integrally together. Each of the molded members 4, 5 joined together is preliminarily fixed to a sandwich panel 3. The molded members 4, 5 have their joint 14 on the outer side, at which they are riveted together by a rivet B', and also on the inner side they form an interlocking joint 15 in a shape fitting the joint on the outer side. It is also possible to equip the molded members 4, 5 with an elastic seal by forming grooves in the surfaces of the joint 14.

Structure of terminal connection in honeycomb sandwich panel

Abstract: PURPOSE: To make a connecting job easily performable through a simple structure and cost reduction promotable as well as to aim at the promotion of lightweightiness. CONSTITUTION: A panel body 2 is made up of making two surface plates 4a and 4b adhere to both upper and lower surfaces of a honeycomb core 3. Two connection fittings 5a and 5b are embedded in each inner part of both these surface plates 4a and 4b of this panel body 2, and those of terminal parts themselves of the panel body 2 are connected to each other via these connection fittings 5a and 5b formed into the specified form each and plural pieces of clamping members 6 including a rivet or the like. COPYRIGHT: (C)1995,JPO

Manufacture of sandwich panel

Abstract: PURPOSE:To provide a manufacturing method for sandwich panel, by which high grade working for arranging the heights of core materials in high accuracy and an expensive countermeasure of laying a brazing filler metal at thicker than the height difference between the core materials are not necessary. CONSTITUTION:At the time of manufacturing the sandwich panel by joining while inserting the metal-made core materials 2 in between two sheets of the metal-made shell materials 1, an electric conductive and cushiony inserting material 3 is interposed in between the shell material 1 and the core materials 2. By pressurize-energizing these shell materials 1 and core materials 2, the electric current is conducted in all joining parts of both materials 1, 2, and sure joining is executed.

Composite sandwich panel having high- temperature 1100degrees combustibility and resistance to penetration

Abstract: PURPOSE: To obtain enough mechanical strength and low FST value by arranging the first fire barrier membrane between the first and the second honeycomb core layers and arranging the second and the third fire barrier membranes on the outside of the first and the second honeycomb core layers. CONSTITUTION: Two honeycomb core layers 2 and 3 are separated by the center septum layer 5 and the surface skins 4 and 6 are respectively provided in front and back of a sandwich panel 1. The center septum layer 5 and the surface skins 4 and 6 are respectively fire barrier membranes and in addition, membranes 7, 8, 9 and 10 are pref. prepregs such as low FST phenolic resin prepregs. The fire barrier membranes 4, 5 and 6 are made of many different materials contg. both an inorg. fiber membrane or an inorg. paper and a vermiculite film. The inorg. paper is used for one of the surface skin or the septum layer with a thickness of 0.254-0.889 mm. The film thickness of the vermiculite mica film barrier is 0.127-0.762 mm.

Light wire sandwich panel for support construction

Abstract: The utility model relates to a light mesh sandwich panel for supporting construction. The utility model is composed of two mesh slices and a light heat-preserving sandwich, the two mesh slices are arranged in parallel, and the light heat-preserving sandwich is positioned between the two mesh slices. According the scientific design, the two mesh slices are connected with each other by oblique wire; so the utility model can form a firm body; thereby, the intensity of the utility model, which is used for bearing the vertical force or the horizontal force can be enhanced. The utility model can be used as the frame of an ordinary protecting wall panel, and the utility model can also be used as the frame of a load-bearing wall panel. The utility model is suitable for the buildings of assembly type.

Method for repairing sandwich panel structure

Abstract: PURPOSE: To reduce apparent specific gravity of a sandwich panel structure, to control costs and weight to be increased by repair, and to secure strength by making the cell of a repair part a rigid body by a resin, a metallic repair agent, and a spacer. CONSTITUTION: In a repairing method in which a resin 8 or a metallic repair agent 8' is injected into a damaged part of a sandwich panel structure, when a face plate 2 is damaged, the face plate 2 of a damaged part is hollowed out, a hollow spacer 7 is inserted into a cell 5, and the resin B or the metallic repair agent 8' is injected into the cell 5 to the full and cured to make the cell a rigid body to secure the strength. COPYRIGHT: (C)1996,JPO

Production method of brazed sandwich panel

Abstract: PURPOSE:To provide a production method of brazed sandwich panel by brazing plural panels at one time without using lubricating plate CONSTITUTION:The panel structure is formed by arranging the face sheets 4, 6, which have a brazing filler metal layer on one side with its brazing filler metal side made inside, on the front and rear faces of the honey comb 2, plural structures are piled and the piled panel structures are placed between the pressure plates 14, 16 through the forming plates 12 and pressurized in heating, subsequently, plural of the honey comb panels 10 are brazed at one time At this time, on the surface opposite to the brazing filler metal layer side of the face sheet 4, 6, a parting agent is coated or an adhesion prevention layer is formed In this way, it prevents the panels from adhesion due to brazing

Honeycomb core sandwich panel

Abstract: The utility model relates to a honeycomb paper core sandwich plate, which is composed of a face layer and a core layer. The utility model is characterized in that the face layer which is an engineering plastic board is in a flat board shape; the core layer is paper core which has a polygon honeycomb structure which is reinforced and solidified, the hollow hole of the honeycomb paper core of the core layer is perpendicular to the face layer, and the periphery of the hollow hole of the honeycomb paper core is bound with the face layer. The utility model has the advantages of light weight, high strength, acoustic insulation, favorable thermal insulation effect, etc. The utility model is suitable for manufacturing various building boards and furniture facilities in residence and office.

Fire-resistant sandwich-panel

Abstract: PURPOSE: To enhance fire-resistance by using a high-melting-point metal skin with improved connection part structure, related to a sandwich panel where a heat-insulating core is held between two metal skins CONSTITUTION: A heat-insulating core 18, first metal skin 14, second metal skin 16, steel joint members 34 and 36 which are, connected to both skins, parallel each other, with a space, to form a central joint tongue 33, and first and second connectors 48 and 50 The connectors are formed of expanded sheet steel, the central joint tongue 33 is flanked by a pair of channels 35 and 37 and extends from the longitudinal edge of the panel, a pair of spaced parallel legs 24 and 26 are formed by marginal portions of the first and second skins and project beyond the main insulating core at the opposite longitudinal edge of the panel, the legs are spaced to form a groove 32 to receive the tongue of an adjacent, similar panel, and the legs accommodated within the channels of the adjacent panel

Heat insulating construction element, especially for roofs and walls.

Abstract: of EP0597182In the case of a heat-insulating structural element, in particular for roof and wall structures, a plurality of material layers (1 - 4) are connected to one another over their entire surface to form a sandwich panel. In this arrangement, a foamed-plastic layer (3) is provided between two outer covering layers (1, 4) which are of the same thickness and are based on wood. A surprisingly large degree of improvement in the sound-insulating capacity is achieved, in the case of such a structural element, in that an intermediate layer (2) based on gypsum, e.g. a gypsum plasterboard, is arranged between the foamed-plastic layer and one (3) of the two outer covering layers (1).