Showing papers on "Sandwich panel published in 1969"

Dilatational‐Mode Sound Transmission in Sandwich Panels

Abstract: Dilational vibration modes have been shown to produce an undesirable “coincidence type” response in the sound‐transmission spectrum of lightweight‐core sandwich panels in the medium to high‐frequency range. In particular, it was found that the dilatational coincidence region often occurs at considerably lower frequencies than those coincidence effects produced by flexural vibration. The governing characteristic frequency equations were developed by employing the Rayleigh‐Ritz Energy Principle for a sandwich panel with variable dimensions and properties. The present solution also employs a general strain energy relation without restricting the skin materials to be identical. Eight characteristic natural frequencies representing dilatational, flexural, and longitudinal vibration were determined for the fundamental as well as higher order modes as a function of panel dimensions and material properties. Throughout this study particular attention was given to the influence of core properties on the dilatational natural frequencies. Experimental panels with various face and core materials were tested under random incidence sound‐transmission conditions and found to compare favorably with the theoretical predictions.

Sandwich panel type structural elements and method of making same

Abstract: A STRUCTURAL ELEMENT OF THE SANDWICH PANEL TYPE. THE CORE IS NOVELLY FORMED BY INTERWEAVING RESIN-IMPREGNATED GLASS CLOTH WEBS AND RIGID SPACER BLOCKS. THE CORE HAS MULTIPLE GLASS CLOTH WEBS, EACH WITH MULTIPLE BLOCK SUPPORTED CORRUGATIONS, WHICH CORRUGATIONS ARE ADJACENTLY OFFSET. THIS CORE PROVIDES ADVANTAGEOUS STRENGTH PROPERTIES TO THE ELEMENT, SPECIFICALLY HIGH STRENGTH-TO-WEIGHT RATIOS, AND, AS WELL, LARGE AREAS FOR BONDING ELEMENT FACE SHEETS TO THE CORE.

Double anchoring mechanical sandwich panel fastener insert

Abstract: A fastener insert which develops clamping anchorage to a panel skin by forming a bulbed secondary head in a shell by compression resulting from drawing a nut into the shell under interfering engagement between the two, and secondary anchorage in the panel core by a plurality of petals which are expanded into the core by action of an annular head on the nut as the nut is drawn into the shell.

Panel construction and method

Abstract: THE METHOD AS DISCLOSED HEREIN INCLUDES APPLYING A COMPRESSIVE FORCE TO THE FACES OF A SANDWICH PANEL IN EXCESS OF THE CRUSHING PROPORTIONAL LIMIT OF THE SANDWICH PANEL AND BELOW THE FORCE AT WHICH THE PANEL STRUCTURALLY FAILS AND SUBSTANTIALLY WEAKENS TO PERMANENTLY REDUCE THE THICKNESS AND INCREASE THE DENSITY OF THE CORE OF THE SANDWICH PANEL. THE COMPRESSIVE FORCE IS APPLIED ALONG A PRESELECTED ZONE SUCH AS A MARGINAL PORTION OF THE SANDWICH PANEL TO REDUCE THE THICKNESS THEREOF WHILE ALLOWING THE THICKNESS OF THE MAIN PORTION OF THE PANEL TO REMAIN SUBSTANTIALLY UNCHANGED. THE PORTION OF REDUCED THICKNESS IS INTEGRALLY JOINED TO THE REMAINDER OF THE PANEL BY A TAPERED TRANSITION PORTION. A SUITABLE ACCESSORY MEMBER SUCH AS AN EDGE MEMBER OR A JOINING MEMBER IS THEN SECURED TO THE MARGINAL PORTION TO INCREASE THE STRENGTH OF AND PROTECT THE MARGINAL PORTION. THE PANELS MAY BE USED FOR VARIOUS PURPOSES SUCH AS PALLETS.

Sound absorptive honeycomb sandwich panel with multilayer, porous, structural facing

Abstract: A sound absorptive honeycomb sandwich panel has a honeycomb core and a light sheet metal backing applied to one end thereof, and has also a porous facing comprising a plurality of layers of foraminous material of substantial structural strength with the layers arranged in random, closely superposed relation, applied to the other end thereof. The multilayer facing, the backing and the core are all integrally interconnected to form the sandwich panel.

Method of producing metal-clad plastic panels

Abstract: A PROCESS FOR THE PRODUCTION OF SANDWICH CONSTRUCTIONS CONSISTING OF (A) AN INNER PLY OF POLYETHYLENE; (B) ADHESION-PROMOTING INTERLAYERS APPLIED TO BOTH SIDES OF THE INNER PLY AND (C) OUTER PLIES OF METAL APPLIED TO THE TWO INTERLAYERS IT IS A CHARACTERISTIC FEATURE OF THE INVENTION THAT SHEETING IS PREPARED CONTINUOUSLY FROM A SPECIAL POLYETHYLENE BY MEANS OF A SCREW EXTRUDER AT A SPECIFIC TEMPERATURE OF THE MATERIAL, THIS SHEETING IS COVERED ON BOTH SIDES WITH A FILM OF A SPECIAL TERPOLYMER BY MEANS OF A PAIR OF ROLLERS, THE RESULTANT LAMINATE IS THEN COVERED CONTINUOUSLY BY MEANS OF A PAIR OF ROLLERS AT A SPECIFIC TEMPERATURE OF THE MATERIAL WITH METAL SHEETING HAVING A SPECIFIC TEMPERATURE AND THE WHOLE IS COMBINED TO FORM A SANDWICH PANEL UNDER A SPECIFIC ROLLER PRESSURE THE PROCCESS GIVE SANDWICH CONSTRUCTIONS HAVING PARTICULARLY GOOD CHEMICAL AND PHYSICAL PROPERTIES IN A SIMPLE WAY

Production of flat structural sandwich constructions

Abstract: A process for the production of sandwich constructions consisting of (a) an inner ply of polyethylene; (b) adhesion-promoting interlayers applied to both sides of the inner ply and (c) outer plies of metal applied to the two interlayers. It is a characteristic feature of the invention that sheeting is prepared continuously from a special polyethylene by means of a screw extruder at a specific temperature of the material, this sheeting is covered on both sides with a film of a special polymer by means of a pair of rollers, the resultant laminate is then covered continuously by means of a pair of rollers at a specific temperature of the material with metal sheeting having a specific temperature and the whole is combined to form a sandwich panel under a specific roller pressure. The process gives sandwich constructions having particularly good chemical and physical properties in a simple way.

Method of forming a foamed sandwich panel

Abstract: A panel adapted to receive transverse compressive stress comprising, two spaced parallel sheets, a plurality of spacers between said sheets each constituted by a tubular skin surrounding expanded plastic foam having cells elongated in a direction parallel to said skin and perpendicular to said sheets, and plastic foam expanded in the remaining volume between said sheets.

Titanium diffusion-bonded honeycomb - Optimum structure for material, joining medium, and configuration.

Abstract: Diffusion-bonded titanium honeycomb has been developed as an outgrowth of all-welded honeycomb in steel and superalloy materials. Uniqueness of the basic concept lies in the minute flanges formed on the core ribbons, which are micro-spot-welded to the skins and in the nesting of ribbons at nodes. High reliability of sandwich panel is achieved by ribbonby-ribbon installation and automatic welding. Structural components are then fabricated from the panels by conventional shop practices: cutting, forming, crushing, and welding. The lack of a foreign bonding agent reduces weight, eliminates contamination, and eliminates temperature limitations other than the skin material itself. Structural integrity has been proven in the extreme heat and sonic environments of steel thrust reversers on commercial aircraft. Typical applications for welded steel, with 30% weight reduction potentials, compared to brazed steel, are engine components, doors, thrust reversers, nozzles, and heat shields. The initial step for titanium diffusion-bonded honeycomb is identical to that of steel, fabrication of panel on a special welding machine. Then the diffusion bonding is achieved by a simple vacuum-anneal heat treatment, during which diffusion occurs at the core-toface sheet interface and at the nodal point connections of the core ribbons. Titanium honeycomb shows strength/weight 50% better than brazed steel honeycomb with fatigue tension KT « 1.5.