Showing papers on "Sandwich-structured composite published in 1973"

Experimental Buckling Loads of Sandwich Panels with Carbon Fibre Faceplates

Abstract: Experiments to determine the overall buckling and faceplate wrinkling loads of sandwich panels with carbon fibre reinforced plastic faces and honeycomb cores when loaded under uniaxial compression are described. The results are compared with theoretical predictions which assume that the faceplates are orthotropic. The effect on the experimental loads of certain coupling terms, which occur in the constitutive equations of those faceplates which are not orthotropic, is then considered.

Free-Edge Effects in the Characterization of Composite Materials

Abstract: In the use of flat specimens for the characterization of composite materials, stress free edges often are encountered. In the case of laminated tension specimens, such free edges induce interlaminar stresses which can disturb the desired state of stress. Large stress concentrations can be induced by free edges, such as in the rail shear test. Other examples include the sandwich beam test. A general review of free-edge problems as related to composite characterization is presented, including a discussion of narrow versus wide specimens. Particular attention is given to the sandwich beam test where a preliminary analysis of the free-edge problem reveals a state of stress which differs from a tensile coupon.

Honeycomb product and process for manufacture

Abstract: A process for the continuous production of low density honeycomb cores for use in lightweight sandwich panels and laminates. Thin webs of structural web material, for example, aluminum foil or kraft paper are first corrugated forming crest and trough areas, followed by the application of adhesive coatings, for example, to the outer surface of the crests and the outer surface of the troughs of layers of the corrugated webs. The layers are then stacked one upon another so as to alternate an adhesive coated corrugated web with an uncoated corrugated web. Heat and/or pressure is then applied to the stack to effect bonding of the stacked material. Expansion of the stack, as by pulling the outer webs of the bonded stack, produces a low density honeycomb core. If desired, prior to expansion, the compressed bonded stack of corrugated webs can be machined precisely into complicated shapes and still maintain the desired shape after expansion in the planes parallel to the layers.

Building sandwich panels

Abstract: Building sandwich panels are provided having one or more facing panels removably supported on a load-carrying frame, facilitating their assembly at a building site, and repair afterwards.

Corrugated cardboard reinforced synthetic foam building panels - reinforrroreccement formed immediately before appln. of the foaming matl.

Abstract: Synth. foam building sandwich panels with corrugated cardboard reinforcement and cardboard outer layers (the foaming material being applied simultaneously on both sides of the reinforcement) are continuously mfd. by shaping the reinforcement webs continuously, after conditioning treatment, immediately before application of the foaming material and passing them, free of stresses, between continuously supplied outer layers. Substantial reduction of manual labour requirement is achieved.

Apparatus for manufacturing sandwich panels

Abstract: A welding machine for fabricating metal sandwich panels having corrugated core, comprising a set of rules for offering up the core, TIG welding blowpipes positioned in a channel at the location where the core is covered with skin strip, HF-ignition welding generators, HF generators in immediate vicinity to the blowpipes, a weld sequencing block, said machine being disposed in order that the core strip is covered subsequent to being corrugated and is then welded beneath the TIG welding blowpipes, electrodes being positioned outside the core.

Lightweight sandwich panels prodn - allowing facing sheets to expand after heating and before final bonding

Abstract: Method fo making panels, esp. for aircraft, consists of applying and pre-condensing adhesive to the core layer of timber or the like, etching the inner faces of the outer layer(s) of e.g. Al sheet to improve bond, lightly applying these to the core (pref. for 3 mins) preheating them and opt. relacing any application pressure (pref. for 15-20 secs) to permit expansion, finally pressing the sheets, with heat briefly onto the core, esp. simultaneously forming the edges, lowering the temp. to 100 degrees C while the sandwich is still in the press.

Design Parameters for Torsion of Sandwich Strips Having Trapezoidal, Rectangular, and Triangular Cross Sections.

Abstract: : Solutions for the elastic torsion of sandwich strips having triangular, rectangular, or trapezoidal cross sections are presented analytically in terms of suitable design parameters. Data obtained from resulting expressions are presented in a series of design curves for normalized values of torsional stiffness and maximum facing and core shear stresses. The analysis is based on the Saint Venant theory of torsion. The sandwich facings are idealized as identical, thin, isotropic membranes, while the core's elastic behavior is characterized by a single transverse modulus of rigidity. (Author-PL)

Crack Measurements in Composite Materials

Abstract: Where crack propagation governs failure of composite materials, understanding of fracture phenomena requires precise determination of running crack behavior. A fast accurate method is proposed for making crack measurements using moire fringes. The method can be applied to stationary as well as running crack length measurement and to measurement of crack opening displacement. Moire fnnges are the interference pattern resulting from the superposition of two gratings. They can be interpreted as contours of constant displacement components [ 1, 2]. If one grating is fixed to a specimen and a second used as a