Showing papers on "Sandwich-structured composite published in 1970"

Insert for sandwich panels

Abstract: A threaded insert is affixed within a sandwich panel with a hardenable liquid adhesive which is forced into intimate contact with the body of the insert by helical ribs on the body which move the liquid adhesive during insertion of the insert into the panel and are engaged by the adhesive to anchor the insert upon hardening of the adhesive. The body is a composite construction including a metallic threaded member surrounded by a sleeve of molded plastic which carries the helical ribs.

Laser welded sandwich panels for shipbuilding and structural steel engineering

Abstract: New structural components, such as sandwich panels, can be efficiently manufactured by using the deep penetration effect typical to high power beam welding techniques. Sandwich structures offer high accuracy, higher structural performance, increased fire safety as well as benefits in assembly. For the first time those structures arc now available on the market. Potential applications cover both shipbuilding and various areas of structural steel engineering such as bridges, railway vehicles and buildings. To provide a base for successful! application, a considerable amount of structural testing along with the development of efficient manufacturing and assembly methods and the approval of the structure by classification societies has been necessary. This paper briefly describes the manufacturing process and operational properties of sandwich panels.

Bending of Clamped Orthotropic Sandwich Plates

Abstract: An approximate solution procedure is presented for rectangular orthotropic sandwich plates under general boundary conditions. A variational method is used to reduce the partial differential equations to a set of ordinary differential equations, which are then solved by numerical integration. The method is used to obtain solutions for a sandwich plate with clamped boundaries. The results from the method compare favorably with existing solutions. A series of graphs suitable for design purposes is presented depicting the variation of the maximum values of the bending moments, shear forces and deflections in square sandwich plates with orthotropic cores for different shear stiffnesses.

Plastic flow and failure of discontinuous-fibre composite materials

Abstract: The stress distribution in a plane discontinuous-fibre composite material having elastic fibres and an elastic-plastic matrix material is obtained for both non-interacting and interacting discontinuities and different degrees of work-hardening. The theoretical predictions, obtained by the finite-element method, are compared with the strain distribution in a model of steel and lead-alloy by the surface-coating photoelastic technique. Composite failure is simulated in the finite-element model and predictions compared with the observations of composite failure made by other workers.

Plastic boat construction

Abstract: Boats constructed of reinforced plastic which are self-buoyant. Fiberglass boats (e.g., runabouts) which will float in an upright position when filled with water have their hulls constructed in part-at-least as foamed-core sandwich panels or laminates. They are characterized by the absence of flotation chambers in the bilge area below the floor and by the presence of more foamed plastic in the laminates above the waterline than below the waterline.

Sandwich-panel building construction

Abstract: A BUILDING IS CONSTRUCTED OF ELONGATED SANDWICH PANELS WITHOUT FRAMEWORK, BY DISPOSING THE SANDWICH PANELS UPRIGHT FOR THE FRONT AND REAR WALLS OF THE BUILDING AND HORIZONTAL FOR THE SIDE WALLS OF THE BUILDING AND HORIZONTAL FOR THE ROOF. THE ROOF CAN BE A SERIES OF INVERTED V''S. THE PANELS ARE CONNECTED BY OVERLAPPING CONNECTORS SECURED ON THE OUTER SIDE OF THEIR OUTER SKINS, AND TO THIS END ARE PROVIDED WITH SPECIAL RIBS AND OVERHANGING EDGE PORTIONS TO WHICH THE CONNECTORS ARE SECURED.

Concrete box-girder bridges as sandwich plates

Abstract: A relatively simple, accurate method for the complete determination of internal moments, shears, and deflections in concrete box girder bridges with statically applied external vertical loads has been developed and is described. The method of analysis used is based on the concept of replacing the actual structure by an equivalent uniform plate which models the behavior of the actual structure. The objectives of the study, which are analyzed in detail, are (1) A discussion of the basis and applicability of the analysis of box girder bridges by sandwich plate theory; (2) presentation and solution of the governing equations for the boundary conditions and loadings considered; (3) the development of procedures for computing governing stiffness parameters; and (4) presentation of results derived for a sample structure and comparision of predicted beam bending moments with corresponding quantities measured in a full scale field test bridge.

Longtime Performance of Sandwich Panels in Forest Products Laboratory Experimental Unit

Abstract: : Performance of selected sandwich panels in a 12- by 38-foot exposure unit was periodically evaluated for various lengths of service up to 21 years. Such panels were constructed of paper honeycomb cores and a variety of facings including plywood, medium-density and high-density hardboard, particleboard, paperboard, cement asbestos, and aluminum. Observations of seasonal bowing of panels were also made over a 15-year period. After 21 years of exposure, the unit was dismantled and re-erected at a new location. During this move all wall, floor, and roof panels were tested for stiffness and selected panels were tested to failure. The plywood-faced panels exhibited a minimum of movement due to temperature and moisture changes, and retained a high proportion of original stiffness and strength properties. Other panel constructions were less stable under moisture and temperature changes. Only a few panels had a material loss in stiffness and most panels retained a strength well above the design load.

Optimum Fibre Orientation Layout Of Composite Sandwich Panels For Maximum Stiffness

Abstract: Composite sandwich panel stiffness as a function of fibre orientation layout of face sheet is examined keeping total mass constant. Two basic layouts are considered: the first using constant fibre orientation and the second having a different fibre angle for each panel quarter. Specimens are tested showing good agreement with the first natural frequencies calculated for their finite element models. Taking fibre angles as design variables both layouts are maximized for the first eigenvalue. Two subsequent partitions are modeled with important stiffness increases achieved.

Transient heat flow in three-dimensional sandwich panels

Abstract: An analytical solution has been developed for transient heat flow in a sandwich panel. Unlike most previous studies which treat only a one -dimensional panel, this study treats both twoand three-dimensional panels. The panel is rectangular in shape, with its core material thick in comparison with the top and bottom laminations . Because of the rather general assumptions under which the solution is developed, this solution may be applied to re-entry vehicles, spacecraft, cryogenic storage vessels, or ocean tankers. Out of the infinite series form of the solution, a criterion is developed. This criterion indicates the dimensionality of the problem; it shows when one-, two-, or three-dimensional aspects of the problem need to be considered. Thus, without actually working the problem, the engineer might use this criterion to judge the complexity of a problem.