Showing papers on "Sandwich-structured composite published in 1976"

Honeycomb-laminate composite structure

Abstract: A honeycomb-laminate composite structure comprising A. a cellular core of a polyquinoxaline foam in a honeycomb structure, and B. a layer of a non-combustible fibrous material impregnated with a polyimide resin laminated on the cellular core, A process for producing the honeycomb-laminate composite structure and articles containing the honeycomb-laminate composite structure.

Transmission of sound through sandwich panels: A reconsideration

Abstract: A reconsideration of a previous study of the transmission loss of sandwich panels is presented. An erroneous calculation of the transmission loss is corrected, and new results are presented. Also, some interesting implications for the design of walls of high transmission loss are pointed out.Subject Classification: [43]55.75.

Heat insulating wall structure for a fluid-tight tank and the method of making same

Abstract: A fluid-tight heat insulated tank wall structure comprising a rigid outer wall, an inner membrane-like impervious primary barrier wall and an intermediate heat insulating material carrying said inner wall and consisting of: an inner end layer of balsa wood or polyvinyl chloride, one composite laminated layer of sandwich panels composed of two spaced plywood plated and filling material interposed therebetween; and an outer end layer of cellular material.

Method for producing heat-resistant composite materials reinforced with continuous silicon carbide fibers

Abstract: A heat-resistant composite material reinforced with continuous silicon carbide fibers is produced by forming a powdery ceramics matrix and the fibers into a composite, and pressing and heating the composite into a sintered composite. The composite material is excellent in the mechanical strength at a high temperature, heat resistance, oxidation resistance and corrosion resistance.

Curved laminate panels

Abstract: Curved sandwich panels having a plastic foam core are prepared by providing a flexibilized foam core, laminating inner and outer skins to the core. The outer skin is laminated to the core at locations other than where the panel will be curved, bending the panel to the desired shape and laminating the outer layer to the core.

Composite materials and processes for their production

Abstract: This invention discloses a composite material consisting of layers of a plastic sheet, a polyurethane ionomer latex foam and a textile material.

Composite sandwich lattice structure

Abstract: This invention relates to a lattice type structural panel utilizing the unidirectional character of filamentary epoxy impregnated composites to produce stiff lightweight structural panels for use in constructing large area panels for space satellites and the like.

On the wrinkling of honeycomb sandwich columns with laminated cross-ply faces

Abstract: In the theoretical and experimental work on the buckling of sandwich panels with laminated faces reported in Refs. 1 and 2, panels which had certain coupling terms present in the constitutive equations for the faces were solved in an approximate manner. The previous theoretical solution for angle-ply lay-ups assumed that there were sufficient layers present to treat the faces as orthotropic, with the Bij coupling terms in the constitutive equations put equal to zero. Further simplifying assumptions were made when comparing theoretical and experimental results in Ref. 2 where tests were carried out on three different types of carbon fibre faces; orthotropic, balanced angle-ply and unbalanced cross-ply. It was only in the first case that an exact theoretical analysis was carried out, and the second case was again treated as an orthotropic panel neglecting coupling between direct and shear deformations and bending and twisting curvatures. The unbalanced cross-ply lay-up, which consisted of two fibre reinforced plastic orthotropic layers, one at 0° to the plate axis and one at 90°, gave rise to large B11 and B22 coupling terms which were taken into account approximately using “reduced stiffness” terms with the orthotropic equations. However, the disparity between theory and experiment was greatest in this case, particularly as far as wrinkling was concerned, where the experimental failure load was 78% higher than the theoretical wrinkling load. This type of cross-ply layup is important since it is used when making carbon fibre sandwich floor panels; it being chosen from the point of view of manufacturing convenience rather than from considerations of strength and stiffness. Furthermore, the bending stresses in the faces, which result from the normal loads, predominate in one direction so that one face is subjected to essentially a uniaxial compressive stress which might cause the faces to wrinkle. In order to study this problem in greater depth, it was decided to carry out further theoretical and experimental work on the simpler problem of the wrinkling of sandwich columns with carbon fibre cross-ply faces.

Method of fixing a sandwich panel to a support

Abstract: Sandwich panels, especially load-bearing panels such as aircraft floors, are fixed to support members by means of ferrules having an aperture sufficient to allow the passage of the shank, but not the head, of a bolt, by a method in which The ferrule is inserted into a hole extending the thickness of the panel so that the body of the ferrule lies within the sandwich panel and the flange contacts a skin of the panel, The flange is bonded to the skin which it contacts, usually by means of a thermosetting or thermoplastic adhesive, The panel is placed against the support member in the desired location with the face of the panel carrying the flange of the ferrule in contact with the support member, and The bolt is passed through the ferrule and screwed to the support member This method allows shorter bolts to be used than was previously possible, resulting in a saving in weight

Analysis of Sandwich Panels with Formed Faces

Abstract: The analysis of foam-filled sandwich panels with light gage, cold-formed metal faces is studied both experimentally and theoretically. Moments and shears affecting the core and those arising from the bending of the rigid faces are combined in the theory. Formulated as an ordinary second order differential equation, and using boundary conditions, expressions are developed for deflection and for flexural stresses in the faces and shear stresses in the core. Experimentally, four different sandwich panels were subjected to uniform loading on simple spans. Strain gages and deflection dials were used. Experimental and theoretical deflections and stresses are in reasonable agreement. Both approaches show a reversal of stresses along the profiles of the formed faces due to bending of such faces about their own centroidal axis, which indicates a plane section of such sandwich panel does not remain plane under bending. The theory is applicable to panels with either one or two formed face(s) and faces of different or the same materials. In case there is only one formed face, the other face is flat.

Method of making curved laminated panels

Abstract: Curved laminated sandwich panels having a plastic foam core and surface skins are prepared by applying pressure sensitive adhesive to at least one of adjacent faces to be joined, interposing a slip sheet between adjacent surfaces of the sheets to be laminated, positioning the sheets to be laminated within a matched die mold, removing the slip sheets and passing the matched die mold through pressure rolls to deform the sheets and conform them to the shape of the mold.

Development of autoclave moldable addition-type polyimides

Abstract: : Chemistry and processing modifications of the poly(Diels Alder) polyimide (PDA) resin were performed to obtain structural composites suitable for 589K (600 deg F) service. This work demonstrated that the PDA resin formulation developed under Contract NAS 3-17770 is suitable for service at 589K (600 deg F) for up to 125 hours when used in combination with Hercules HTS graphite fiber. Sandwich panels were autoclave molded using PDA/HTS skins and polyimide/glass honeycomb core. Excellent adhesion between honeycomb core and the facing skins was demonstrated. Fabrication ease was demonstrated by autoclave molding three-quarter scale YF-12 wing panels. jg

Evaluation of Load-Bearing Honeycomb Core Sandwich Panels

Abstract: : The report describes an investigation of the performance of three-ply and five-ply paper honeycomb core sandwich panels. The core of the three-ply material consisted of metallic skins bonded to a cellular paper ply; the five- ply construction had 1/8-in.(3.2 mm) hardboard or asbestos board bonded to the metal skin which was bonded to the honeycomb paper. The panels were tested for fire safety, superficial damage, thermal conductivity, and durability. It was found that addition of backup plies did not significantly affect performance in thermal conductivity, durability, or large import loads; however, a significant increase in performance was achieved in localized superficial damage and five endurance times. The improved fire performance of the five-ply panels was still decidedly inferior to that of conventional wood stud construction. Further study should be made to determine if simple changes in the basic design of the panel are available which could bring the fire performance up to the level of conventional construction.

Stability of Flat, Clamped, Rectangular Sandwich Panels Subjected to Combined Inplane Loadings.

Abstract: : The general stability of flat, rectangular sandwich panels loaded by combined biaxial compression, biaxial edgewise bending and edgewise shear is investigated The analysis is applicable to sandwich structures having isotropic face sheets and orthotropic cores The analysis procedure is based upon a linear potential energy formulation and the Ritz method of discretization For the case of clamped boundaries, it is shown that the equation of the potential energy must be minimized by the use of matrices The analysis leads to an infinite series solution for which the eigenvalues of the equation of matrices are monotonically decreasing This analysis is presented in detail with the equations for the potential energy presented in three Appendices The equation presented in Appendix C is the expression used to minimize the potential energy of a flat, clamped sandwich panel (Author)

Preliminary weight and costs of sandwich panels to distribute concentrated loads

Abstract: Minimum mass honeycomb sandwich panels were sized for transmitting a concentrated load to a uniform reaction through various distances. The form skin gages were fully stressed with a finite element computer code. The panel general stability was evaluated with a buckling computer code labeled STAGS-B. Two skin materials were considered; aluminum and graphite-epoxy. The core was constant thickness aluminum honeycomb. Various panel sizes and load levels were considered. The computer generated data were generalized to allow preliminary least mass panel designs for a wide range of panel sizes and load intensities. An assessment of panel fabrication cost was also conducted. Various comparisons between panel mass, panel size, panel loading, and panel cost are presented in both tabular and graphical form.

Analytical structural efficiency studies of borsic/aluminum compression panels

Abstract: Analytically determined mass-strength curves, strain-strength curves, and dimensions are presented for structurally efficient hat-stiffened panels, corrugation-stiffened panels, hat-stiffened honeycomb-core sandwich panels, open-section corrugation panels, and honeycomb-core sandwich panels. The panels were assumed to be fabricated from either titanium, borsic/aluminum, or a combination of these materials. Borsic/aluminum panels and titanium panels reinforced with borsic/aluminum were lighter and stiffer than comparably designed titanium panels. Reinforced titanium panels had the same extensional stiffness as comparably designed Borsic/aluminum panels. For a given load, the structural efficiency of the hat-stiffened honeycomb-core sandwich panel was higher than the structural efficiency of the other stiffened panels.