Showing papers on "Sandwich panel published in 1988"

Lightweight sandwich designed for making multilayer structures resistant to impact and thermal aggressions

Abstract: The invention concerns a sandwich designed for making multilayer structures resistant to impact and thermal aggressions of the type including a core 2 interposed between an external skin 1 and an internal skin 3. The external skin panel 1 consists of an assembly of at least three layers made integral by sealing or bonding: a first layer 4 made of composite material, a second layer 5 made of a synthetic cellular material with a low thermal conductivity coefficient, a third layer 6 obtained by lamination of a composite material. The second layer 5 consists of a honeycomb and the composite material of the first layer 4 and third layer 6 consists of glass fiber reinforced epoxy resin. A nonwoven polyester layer 7 is interposed between layers 4 and 5. The sandwich panel includes a metal sheet 8 adhering by cofusion to layer 5 via a thermal plastic film 9, said sheet being made of aluminum or aluminum alloy, steel or titanium which can be in the form of a film with a thickness below 1 mm. Application to making a wall for construction, in particular of buildings.

Process for making a honeycomb core for a sandwich panel

Abstract: The process for making a honeycomb core from a fibrous material preimpregnated with a curable plastic for a lightweight sandwich panel comprises the sequence of following process steps: a. Alternate layering of a prepreg layer 6 and a lattice 4, a prepreg layer 6, a lattice 4, a prepreg layer 6, a lattice 4 and so on until the predetermined thickness of the stack is reached, the lattices 4 being formed by parallel rods 5 at a predetermined spacing and the rods 5 of one lattice 4 being offset in a staggered arrangement with respect to the rods 5 of a neighbouring lattice 4; b. Pressing of the stack perpendicularly to the axes of the rods 5; c. Curing of the stack under pressure and heat, and d. Drawing out of the rods 5 from the stack. The process can be carried out both with horizontal layering and with vertical layering. In particular in the case of vertical layering it is of advantage that all the operations involved can be performed largely automatically by means of drivable devices.

Reinforced composite sandwich panel assembly

Abstract: A composite panel assembly for walk-in coolers and freezers and similar structures has a thickness of low strength insulation sandwiched between two facings. A reinforcing structural member is bonded to the insulation side of one of the facings and extends across at least about half of the thickness of the insulation but is spaced from the opposite facing. The reinforcing member does not provide a direct thermal path between facings; thus preventing condensation on the facing during high humidity and/or low temperature conditions.

Manufacture of plastic foam sandwich panel

Abstract: PURPOSE:To prevent generation of a void becoming the cause of a deterioration in adhesive strength between a plastic foam and a facial material, or a depression, on a swelling of the facial material at the time of filling and foaming, by interposing a reticulated sheet between a panel face and the plastic foam CONSTITUTION:At the time of manufacture of a sandwich panel by filling and forming a plastic foam between a pair of a top and bottom panels, reticulated sheets S are interposed among a top and bottom panel faces P, P of the sandwich panel and a plastic foam F The reticulated sheet grasps at bubbles to be generated on the interface with a panel facial material at the time of filling and foaming of the plastic foam, and coalescence and growth of the bubbles are inhibited Effective mesh size is about 5-30mm mesh It is preferable that a material forming the mesh is made into a state of twisted yarn so that the bubbles are stuck to the same through surface tension or gas to which foaming pressure has been applied can be entrapped in the same It is preferable since function reinforcing strength also is displayed to make use of combination yarn of glass fibers of the extent of 01-05mm

Sandwich panel for interior decoration and method of making such panel

Abstract: Sandwich panel for interior decoration having a tough surface. It can be used in particular for work tops 1 in fitted kitchens. An outer layer 2 is designed as a preformed component which contains aluminium trihydroxide bonded with cured synthetic resin. An underlayer 4 consists of a water-impervious plastic sheet material suitable for screwing firmly in place. In between there is an intermediate layer 3 based on a plastic foam material. The invention also relates to a method of making such a sandwich panel and to a method of making a panel composite from such sandwich panels.

Bonding structure between panel and joint fitting

Abstract: PURPOSE:To make the thickness of a bonding layer between a sandwich panel and a joint fitting uniform and consequently prevent the ununiformity in bonding by a method wherein a woven fabric and adhesive are interposed in a joint between the sandwich panel and the joint fitting. CONSTITUTION:In a bonding structure between a panel and a joint fitting, the end part of the panel 1 is covered with a woven fabric 4, which is impregnated with adhesive 3, and, after that, put in a joint fitting 2 for attaching in order to bond both of them to each other by adhesive 3. In this case, by laminating the woven fabric 4 which is bent in a U-shape onto the end part of the panel 1, the favorable insertion of the panel in the joint fitting 2 is realized because no shifting of the woven fabric occurs. By attaching the joint fitting 2 to the panel as mentioned above or by being guided by the woven fabric 4, no scraping-off of the adhesive 3 occurs and consequently the adhesive 3 is held in the spaces of the woven fabric 4. In addition, the thickness of the woven fabric 4 determines the thickness of the adhesive 3 and consequently the thickness of the adhesive 3 on the upper and lower surfaces of the panel are held uniform.

Minimum Weight of a Sandwich Panel

Abstract: The least‐weight problem of a sandwich panel with a truncated, hollow, hexagonal core, and subjected to a given bending moment along each edge is analyzed in this paper. In order to meet the practical manufacturing requirements and be within allowable stress limits, constraints are placed on the geometrical dimensions of the structural parts of the sandwich panel as well as on the physical strength, such as the allowable stresses. Upper and lower limiting values are assigned for each of the design variables. Through the use of the penalty function, the minimization problem subjected to a set of twenty inequality constraints is changed to a sequence of unconstrained ones. The modified Fletcher‐Powell method is used by a proper choice of the penalty parameter and the reduction factor. The methodology presented here can be extended to include multiple loading conditions, bending rigidity, and shear rigidity requirements, which present no additional difficulties except to increase the number of constraints.

High-performance sandwich panels made from braided tubes

Abstract: A light weight, high-performance sandwich panel was developed using thin walled braided tubes as the core material. The panels have certain specific advantages over conventional honeycomb sandwich panels including superior skin-core bonding, integral conduit systems and self-draining thereby avoiding moisture accumulation. A short manufacturing process leads to a cost effective product. The technology of the tube production is not material-specific, so any reinforcing fiber can used in conjunction with a large number of resin systems including thermoplastic resins. The braided tubes used as the core can be produced in a wide variety of cross-sectional shapes and sizes so the panels can be designed to meet various specific functions. 6 figures, 1 table.

Optimum Design Methods for Structural Sandwich Panels

Abstract: : Structural sandwich panels are composed of two thin, stiff skins separated by a light weight core. The faces are typically strong materials such as aluminum fiber reinforced composites, while honeycombs or foams are used in the core. The separation of the faces increase the moment of inertia of the panel with minimum increase in weight. Because of this, these panels are extremely efficient in bending and are used in applications where the weight of the member is critical: aircraft, marine, and land vehicles; portable structures; construction in remote areas; roofing shells; and some types of sports equipment (e.g., modern downhill skis). In all of these, the mechanical behavior of the sandwich panel depends on the strength and stiffness of the face and the core, on the geometry of the panel (the core and face thicknesses), and on the bond strength between the faces and the core. The goal of this research is to determine the core density as well as the core and face thicknesses that minimize the weight of a sandwich panel for given structural requirements. This will improve the minimum design of structural sandwich panels in a manner not previously possible.

Lightweight sandwich panel intended for the production of multilayer structure withstanding impacts and heat attacks

Abstract: A sandwich panel intended for the production of partitions, for example for building, of the type comprising a core 2 placed between two sole plates, outer 1 and inner 3. The outer sole plate 1 consists of a set of at least three layers integrally joined together by welding or adhesive bonding: a first layer 4 made of a composite material, a second layer 5 made of a cellular synthetic material with a low thermal conductivity coefficient, a third layer 6 obtained by lamination of a composite material. The second layer 5 consists of a honeycomb and the composite material of the first 4 and third 6 layers consists of resins reinforced with glass fibres. The resin incorporated into the first layer 4 is chosen from the group consisting of epoxy, polyester, phenolic or vinyl ester resins and the resin incorporated into the third layer 6 is an epoxy resin. The second layer 5 consists of polypropylene, a film 7 made of nonwoven polyester being arranged between the first 4 and second 5 layers and a layer 8 consisting of an aluminium foil is placed between the second 5 and third 6 layers. Application to the production of a wall for building construction.

Process for producing a sandwich panel

Abstract: In a process for producing a sandwich panel having a core of wood-based material between two layers of plastic, at least one of the layers of plastic being produced by means of a polymer casting compound containing an inorganic filler, to achieve the effect of an improved appearance of the panel it is proposed to apply a colouring layer on the layer of filled plastic, adjacent to the core.

The work of CIB W56

Abstract: Paavo Hassinen from the Laboratory of Structural Engineering at the Technical Research Centre of Finland (VTT) and Pentti Aysto from the collaborating company YIT‐Corporation, Makrotalo, study the short term static properties of a four layer sandwich panel and compare it with the usual three layer panel. The results are based on the calculations and loading tests carried out in the laboratory at VTT.