Showing papers on "Sandwich panel published in 1984"

Sliding roof having a sliding inside roof lining

Abstract: A sliding roof for motor vehicles having a transparent rigid sliding cover by means of which an opening in the roof can be selectively closed or can be exposed at least partially. A frameless sliding inside cover lining is provided that can be displaced at least in the cover sliding direction independently from the sliding cover and is guided at its lateral edges. The sliding inside cover lining is formed of a sandwich panel having a core layer and a cover layer that is applied to said core layer at least on one side. In the area of its lateral edges, the sandwich panel is squeezed together reducing the core thickness and increasing its density to form sliding guide edges.

Nonlinear Response of Double Wall Sandwich Panels

Abstract: An analytical study is presented to predict the nonlinear response of a double wall sandwich panel system that is subjected to random-type loading. Viscoelastic and nonlinear spring-dashpot models are chosen to characterize the behavior of the core. The nonlinear panel response is obtained by utilizing modal analyses and Monte Carlo simulation techniques. Numerical results include the response spectral densities, root-mean-square responses, and probability density function histograms. It is found that by proper selection of the dynamic parameters and damping characteristics, the structural response can be significantly reduced.

Structural design and analysis of concrete sandwich panels and their practical applications

Abstract: The concept of a concrete sandwich panel originated in the United States in 1906 where a building was constructed with sandwich tilt-up wall panels. Since then sandwich panels have developed gradually and have continued to improve. -- There are two types of concrete sandwich wall panels: (1) Architectural wall panels (non-composite type), and (2) Load bearing wall panels (composite and non-composite type). -- In general, the non-composite type of load bearing panel is used more commonly because there are less limitations compared with the composite types. This thesis deals with the structural design and analysis of the non-composite type of load bearing wall panel. -- In the past, certain problems besetted architects, engineers, and contractors working with concrete sandwich panels. These problems are associated with: -- (1) Bonding between concrete and insulation -- (2) Joints in panel -- (3) Panel connections -- (4) Control of cracking. -- This study has been undertaken with the aim of solving some of these problems. Three experiments were conducted accordingly to determine the behavior of concrete sandwich panels. The first experiment was to investigate the effects of heating and cooling on sandwich panels and to compare the experimental results with theoretical calculations. The principal results of this experiment demonstrated the effects on concrete sandwich panels under varying thermal conditions. These results should serve as a guideline for the design of joints in sandwich panels. The second and third experiments were initiated to investigate and compare the bending stresses, deflections and shear strength in concrete sandwich panels either with or without shear connectors. The panels were subjected to a simulated uniformly distributed load under simply supported conditions. It can be concluded from the experimental results that a well designed anchor system joining the concrete sandwich panel faces through the core insulation is a fundamental requirement in the future production of sandwich wall panels in order to obtain full shear transfer between the faces. Without these shear connectors, a concrete structural sandwich panel will usually fail by shear of the bond between the core and faces or by shear failure of the core itself. -- The deflection on a sandwich panel is the sum of ordinary bending deflection and an additional deflection associated with shear deformation of the core. Experimental results showed that deflections were mainly associated with shear deformation of the core for panels without shear connectors. -- Deflections measured were less for panels containing shear connectors. For both panels, from theoretical calculations, it was found that the deflections were mainly associated with shear deformation, with less than 1% due to bending. -- A proper shear connector system transfers all lateral loads including wind forces from the exterior face to the interior structural face of the panel. Hence the sleeve anchor, torsion anchors and connector pins play a very important part in the performance of concrete sandwich panels. Prestressing techniques can also improve the design of such panels and have been widely used in recent developments of sandwich panels. -- For this study, a typical non-composite type of concrete sandwich panel was selected as a design example. For the design of such concrete sandwich panels, the following factors were carefully considered: -- (1) The thickness of both faces of the panel -- (2) The loading conditions -- (3) The fire resistance of the sandwich panel -- (4) The temperature gradient between the faces, and -- (5) The panel anchor system.

Honeycomb sandwich structure for future space transportation systems with integral cryogenic tankage

Abstract: This paper presents the status of the structural development of an integral cryogenic-tankage/hot-fuselage concept for future Space Transportation Systems (STS). The concept consists of a honeycomb sandwich structure which serves the combined functions of containment of cryogenic fuel, support of vehicle loads, and thermal protection from an entry heating environment. The inner face sheet is exposed to a cryogenic (LH2) temperature of -423°F during boost; and the outer face sheet, which is slotted to reduce thermal stress, is exposed to a maximum temperature of HOOT during a high-altitude, gliding entry. A fabrication process for a Ren£ 41 honeycomb sandwich panel with a core solidity less than 1% has been developed, which is consistent with desirable heat treatment processes for high strength. Preliminary structural allowables and thermal properties for use in structural system studies have been determined; two 1 x6 ft panels have been tested with combined thermal and mechanical loads; and the effects of slots used to reduce stresses in the outer face sheet on the lower surface of the vehicle have been evaluated in the cryogenic environment associated with containment of LH2 fuel. Based on the work presented in previous system studies and the hardware development described herein, the Rene' 41 honeycomb sandwich appears to be a viable structural concept for an integral cryogenictank/hot-fuselage structure; however, additional in-depth studies, hardware development, and testing are required to verify the concept fully.

Radiant heating tests of several liquid-metal heat-pipe sandwich panels

Abstract: Integral heat pipe sandwich panels, which synergistically combine the thermal efficiency of heat pipes and the structural efficiency of honeycomb sandwich construction, were conceived as a means of alleviating thermal stress problems in the Langley Scramjet Engine. Test panels which utilized two different wickable honeycomb cores, facesheets with screen mesh sintered to the internal surfaces, and a liquid metal working fluid (either sodium or potassium) were tested by radiant heating at various heat load levels. The heat pipe panels reduced maximum temperature differences by 31 percent with sodium working fluid and 45 percent with potassium working fluid. Results indicate that a heat pipe sandwich panel is a potential, simple solution to the engine thermal stress problem. Other interesting applications of the concept include: cold plates for electronic component and circuit card cooling, radiators for large space platforms, low distortion large area structures (e.g., space antennas) and laser mirrors.