Showing papers on "Sandwich panel published in 1999"

The Behavior of Sandwich Structures of Isotropic and Composite Materials

Abstract: SANDWICH STRUCTURES: ORIGINS, ADVANTAGES, AND USES Description of Various Sandwich Constructions Advantages of Sandwich Construction over Construction Monocoque Thin Walled Construction Origins of Sandwich Construction Uses of Sandwich Construction Present Approach to Analysis Problems References ANISTROPIC ELASTICITY AND COMPOSITE LAMINATE THEORY Introduction Derivation of the Anisotropic Elastic Stiffness and Compliance Matrices The Physical Meaning of the Components of the Orthotropic Elasticity Tensor Methods to Obtain Composite Elastic Properties from Fiber and Matrix Properties Thermal and Hygrothermal Considerations Time-Temperature Effects on Composite Materials High Strain Rate Effects on Material Properties Laminae of Composite Materials Laminate Analysis [A], [B], and [D] Stiffness Matrices for a Mid-Plane Symmetric Sandwich Structure Piezoelectric Effects Problems References DERIVATION OF THE GOVERNING EQUATIONS FOR SANDWICH PLATES (PANELS) Introduction Plate Equilibrium Equations The Bending of Composite Material Laminated and/or Sandwich Plates: Classical Theory Classical Plate Theory Boundary Conditions Analysis of Composite Materials Laminated and/or Sandwich Panels Including Transverse Shear Deformation Effects Boundary Conditions for a Plate Using the Refined Plate Theory Laminated or Sandwich Plate on an Elastic Foundation Laminated or Sandwich Plates Subjected to Dynamic Loads Problems References BEAMS, COLUMNS, AND RODS OF COMPOSITE MATERIALS Development of Classical Beam Theory Some Simplified Sandwich-Beam Solutions Eigenvalue Problems of Sandwich Beams: Natural Vibrations and Elastic Stability Other Considerations Problems References ENERGY METHODS FOR SANDWICH STRUCTURES Introduction Theorem of Minimum Potential Energy Analysis of a Beam in Bending Using the Theorem of Minimum Potential Energy Reissner's Variational Theorem and Its Applications Static Deformation of Moderately Thick Beams Flexural Vibrations of Moderately Thick Beams Flexural Natural Frequencies of a Simply Supported Beam Including Transverse Shear Deformation and Rotatory Inertia Effects Minimum Potential Energy for Rectangular Plates A Rectangular Composite Material Plate Subjected to Lateral and Hygrothermal Loads In-Plane Shear Strength Determination of Composite Materials in Laminated and Sandwich Panels Problems References SOLUTIONS FOR RECTANGULAR SANDWICH PLATES Introduction Navier Solutions for Rectangular Sandwich Plates Levy Solutions for Plates of Composite Materials Perturbation Solutions for the Bending of a Composite Material Sandwich Plate, with Mid-Plane Symmetry and No Bending-Twisting Coupling Isotropic Sandwich Panels Subjected to a Uniform Lateral Load Minimum Weight Optimization for a Sandwich Panel Subjected to a Distributed Lateral Load Analysis of an Isotropic Sandwich Plate on an Elastic Foundation Subjected to a Uniform Lateral Load Static Analysis of Sandwich Plates of Composite Materials Including Transverse Shear Deformation Effects Exact Solution Other Considerations Problems References DYNAMIC EFFECTS ON SANDWICH PANELS Introduction Natural Flexural Vibrations of Sandwich Plates: Classical Theory Natural Flexural Vibrations of Sandwich Plates Including Transverse Shear Deformation Effects Forced-Vibration Response of a Sandwich Plate Subjected to a Dynamic Lateral Load Dynamic Response of Sandwich Plates to Localized Loads Large Amplitude Nonlinear Oscillations of Sandwich Plates Simply Supported on All Edges Linear and Nonlinear Oscillations of Specially Orthotropic Sandwich Panels with Various Boundary Conditions Vibration Damping Problems References THERMAL AND MOISTURE EFFECTS ON SANDWICH STRUCTURES General Considerations Derivation of the Governing Equations for a Thermoplastic Isotropic Plate Boundary Conditions General Treatment of Plate Nonhomogeneous Boundary Conditions Thermoelastic Effects on Beams Self-Equilibrium of Thermal Stress Rectangular Composite Material Plate Subjected to Lateral and Hygrothermal Loads References ELASTIC INSTABILITY (BUCKLING) OF SANDWICH PANELS General Considerations The Buckling of an Orthotropic Sandwich Plate Subjected to In-Plane Loads Classical Theory Elastic Stability of a Composite Sandwich Panel Including Transverse Shear Deformation and Hygrothermal Effects The Buckling of an Isotropic Plate on an Elastic Foundation Subjected to Biaxial In-Plane Compressive Loads The Buckling of Honeycomb Core Sandwich Panels Subjected to In-Plane Compressive Loads The Buckling of Solid- or Foam-Core Sandwich Panels Subjected to In-Plane Compressive Loads Buckling of a Truss-Core Sandwich Panel Subjected to Uniaxial Compression Elastic Stability of a Web-Core Sandwich Panel Subjected to a Uniaxial Compressive In-Plane Load Buckling of Honeycomb-Core Sandwich Panels Subjected to In-Plane Shear Loads Buckling of Solid-Core or Foam-Sandwich Panel Subjected to In-Plane Shear Loads Buckling of a Truss-Core Sandwich Panel Subjected to In-Plane Shear Loads Buckling of a Web-Core Sandwich Panel Subjected to an In-Plane Shear Load Other Considerations Problems References STRUCTURAL OPTIMIZATION TO OBTAIN MINIMUM-WEIGHT SANDWICH PANELS Introduction Minimum Weight Optimization of Honeycomb-Core Sandwich Panels Subjected to a Unidirectional Compressive Load Minimum Weight Optimization of Foam-Core Sandwich Panels Subjected to a Unidirectional Compressive Load Minimum Weight Optimization of Truss-Core Sandwich Panels Subjected to a Unidirectional Compressive Load Minimum Weight Optimization of Web-Core Sandwich Panels Subjected to a Unidirectional Compressive Load Minimum Weight Optimization of Honeycomb-Core Sandwich Panels Subjected to In-Plane Shear Loads Minimum Weight Optimization of Solid- and Foam-Core Sandwich Panels Subjected to In-Plane Shear Loads Minimum Weight Optimization of Truss-Core Sandwich Panels Subjected to In-Plane Shear Loads Minimum Weight Optimization of Web-Core Sandwich Panels Subjected to In-Plane Shear Loads Optimal Stacking Sequences for Composite Material Laminate Faces for Various Sandwich Panels Subjected to Various Loads Problems References SANDWICH SHELLS Introduction Analysis of Sandwich Cylindrical Shells under Axially Symmetric Loads A General Solution for Orthotropic-Sandwich Cylindrical Shells under Axially Symmetric Loads Shells with Mid-Plane Asymmetry Other Considerations Problems References BUCKLING OF SANDWICH CYLINDRICAL SHELLS Buckling of a Solid- or Foam-Core Sandwich Cylindrical Shell with Isotropic Faces Subjected to an Axially Symmetric Compressive End Load Buckling of a Solid- or Foam-Core Sandwich Cylindrical Shell with Orthotropic Composite Faces Subjected to an Axially Symmetric Compressive Load Buckling of a Honeycomb-Core Sandwich Cylindrical Shell with Composite Faces Subjected to an Axially Symmetric Compressive End Load Overall Buckling of Sandwich Cylindrical Shells Subjected to an Overall Bending Moment Buckling of a Sandwich Cylindrical Shell Due to External Pressure Buckling of a Sandwich Cylindrical Shell Due to Torsion Dynamic Buckling Problems References MINIMUM WEIGHT OPTIMIZATION OF SANDWICH CYLINDRICAL SHELLS General Discussion Minimum Weight Optimization of a Solid Foam-Core Sandwich Cylindrical Shell with Isotropic Faces Subjected to an Axially Compressive Load Minimum Weight Optimization of a Solid- or Foam-Core Sandwich Cylindrical Shell with Orthotropic Composite Material Faces Subjected to an Axially Compressive Load Minimum Weight Optimization of a Honeycomb-Core Sandwich Cylindrical Shell with Composite Material Faces Subjected to an Axially Symmetric Compressive Load Problems References APPENDIX 1: Core Materials APPENDIX 2: Face Materials APPENDIX 3: American Society for Testing Materials (ASTM) Standards for Sandwich Structures and Materials INDEX

The strength characteristics of aluminum honeycomb sandwich panels

Abstract: Aluminum sandwich construction has been recognized as a promising concept for structural design of lightweight transportation systems such as aircraft, high-speed trains and fast ships. The aim of the present study is to investigate the strength characteristics of aluminum sandwich panels with aluminum honeycomb core theoretically and experimentally. A series of strength tests are carried out on aluminum honeycomb-cored sandwich panel specimen in three point bending, axial compression and lateral crushing loads. Simplified theories are applied to analyze bending deformation, buckling/ultimate strength and crushing strength of honeycomb sandwich panels subject to the corresponding load component. The structural failure characteristics of aluminum sandwich panels are discussed. The test data developed are documented.

Mechanical behaviour of cellular core for structural sandwich panels

Abstract: This paper deals with the analysis of the mechanical properties of the core materials for sandwich panels. In this work, the core is firstly a honeycomb and secondly tubular structure. This kind of core materials are extensively used, notably in automotive construction (structural components, load floors...). For this study, three approaches are developed: a finite element analysis, an analytical study and experimental tests. Structural members made up of two stiffs, strong skins separated by a lightweight core (foam, honeycomb, tube...) are known as sandwich panels. The separation of the skins by the core increases the inertia of the sandwich panel, the flexure and shear stiffness. This increase is obtained with a little increase in weight, producing an efficient structure to resist bending and buckling loads. A new analytical method to analyse sandwich panels core will be presented. These approaches (theoretical and experimental) are used to determine elastic properties and ultimate stress. A parameter study is carried out to determine elastic properties as a function of geometrical and mechanical characteristics of basic material. Both theoretical and experimental results are discussed and a good correlation between them is obtained.

Rigid sandwich panel acoustic treatment

Abstract: An acoustic treatment for the air ducts of a gas turbine engine. The acoustic treatment generally includes a facesheet having a plurality of holes therein, a backplate spaced apart from the facesheet, and a plurality of interconnected cells between the facesheet and backplate. Each of the cells is defined by walls attached to the facesheet and the backplate, and at least some of the walls are formed of a porous material so that air is able to flow through the cells in a direction parallel to the facesheet and backplate.

Flush panel spacer and method and apparatus of installing the same

Abstract: A method of installing an insert in a sandwich panel for mounting a fastener includes making a hole in the panel and inserting a spacer having a height greater than the thickness of the panel. An entrance rim of the spacer extends above an upper surface of the panel and a setting tool exerts a force on the entrance rim to force it into the hole and to position an upper edge of the entrance rim flush with the panel surface. The spacer can include an annular groove on an interior wall of the entrance rim to facilitate the cold working deformation during an installation in the panel and a hole engaging surface to align and maintain the spacer within the hole. An outer exterior surface of the entrance rim can be indented and coated with a first sealing compound to ensure a watertight seal with the panel. A second sealant material can be provided within the entrance rim for sealing with a head of any fastener extending through the spacer. An improved floor panel with spacer is accordingly provided for aircraft.

Bending of Curved Sandwich Panels with a Transversely Flexible Core-Closed-Form High-Order Theory:

Abstract: The bending behavior of a curved sandwich panel with a transversely flexible core, ie, "soft" in the out of plane direction is derived It is formulated using a rigorous systematic closed-form approach based on variational principles The effects of the transversely flexible core are incorporated resulting in non-linear patterns, denoted also as high-order effects, for the inplane and the transverse deformations through the height of the core The governing equations along with the associated boundary and continuity conditions for a general type of sandwich panel, ie, unidentical skins, composite laminated or metallic and a "soft" core are derived General type of boundary conditions, including spring conditions, as well as different conditions at upper and lower skins at the same section, are implemented and the effects of "stiff' edge inserts, denoted as global boundary conditions, along with the induced localized effects are considered Localized effects at support regions with or without edge stif

Boundary condition effects in buckling of soft core sandwich panels

Abstract: The effects of boundary conditions on the critical load level and the corresponding deflection mode shape of sandwich panels with a “soft” core due to in-plane loads are presented. The study is conducted using a closed-form high-order linearized buckling analysis that includes the influence of the transverse flexibility of the core as well as of the localized effects on the overall sandwich panel behavior, and allows the use of different boundary conditions for the upper and lower skin at the same section. The panel construction is general and consists of two skins (not necessary identical), metallic or composite-laminated symmetric, and a soft core made of foam or a low-strength honeycomb. The closed-form high-order analysis yields the general buckling behavior of the structure, which means that the solutions obtained allow for interaction between the skins and the core. The solutions are general and are \Inot\N based on separation of the buckling response on several types of uncoupled buckling modes, such as overall buckling, skins wrinkling, etc., as commonly used in the literature. The numerical scheme consists of finite differences to approximate the governing equations of the closed-form high-order formulation and to transform the set of linearized governing differential equations into an eigenvalue problem that is solved using the deflated iterative Arnoldi procedure. The influence of a general type of boundary conditions, including different conditions throughout the height of the same section and nonidentical conditions at the upper and lower skin, as well as of the core properties, on the buckling behavior of the sandwich panels is considered. The discrepancy between the Timoshenko-Reissner model and the present formulation is discussed. In particular, a partial fixity phenomenon due to the existence of the pinned boundary conditions, i.e., simply supported conditions, at the upper and lower skins at the edge is demonstrated. It is shown that the core properties affect the buckling loads and the corresponding modes of the panel in such a way that the structures with identical boundary conditions but with different cores may undergo different types of buckling such as overall and local as well as interactive loss of stability. The effect of an edge concentrated moment, induced by a couple and exerted on the skins only is also studied.

Structural behaviour of sandwich panel shear walls: An experimental analysis

Abstract: Within a comprehensive research project devoted to analyse the contributing effect of cladding panels on the structural behaviour of steel frames under horizontal loads, a suitable experimental procedure has been set up in order to characterise the main behavioural parameters of specific shear walls. In particular, with regard to light-weight sandwich panels, which are currently used in building as enclosure elements, monotonic and cyclic full-scale shear tests have been performed on both single connection specimens and pin-jointed steel frames branced by infill panels. Such an activity, whose main results are summarised in this paper, firstly provides the experimental evidence as basis for setting up numerical and analytical intepretative models. Besides, it supplies useful information on the possibility to use this panel typology as shear wall components. Finally, it points out how their shear performance can be improved through simple modifications of standard prototypes.

Nonlinear Behavior of Sandwich Panels with a Transversely Flexible Core

Abstract: Nonlinear behavior of sandwich panels with a transversely flexible core is presented. The study is based on a highorder nonlinear formulation that includes the influence of the transverse flexibility and shear resistance of the core on the panel behavior, thus allowing for interaction between the facings through the core thickness. The solutions obtained are general and are not based on decoupling of the local and global responses as commonly used in the literature. The governing equations along with the appropriate boundary and continuity conditions are presented, and the solution approach is outlined. The path-following algorithm devised is based on the natural parameter and the arc-length continuation techniques. The example problems discussed include a concentrated line load exerted at midspan of the panel, couples applied at the panel edges, and compression of an asymmetric sandwich panel. Mode interaction observed in the panel behavior is shown to be a result of the flexibility of the "soft" core. Variations in the boundary conditions of the sandwich panel as well as in the layout of the compressive longitudinal loads are also shown to shift its response from an imperfection-sensitive to an imperfection-nonsensitive one and vice versa.

Equivalent Stiffness Parameters of Truss-Core Sandwich Panel

Abstract: A sandwich unit in which the two facing plates are separated but rigidly connected by two inclined trusses (truss-core panel unit) is investigated. A number of these units can be welded along the facing plates to form a truss-core sandwich panel. The sandwich panel is transformed into an equivalent homogeneous orthotropic plate for which analytical solution or 2-D finite element solution may be obtained. This requires the development of bending, twisting and transverse shear stiffnesses of the orthotropic plate. Formulation of these stiffness parameters is presented. By incorporating these derived stiffness parameters into analytical solutions, the response of several truss-core panels are obtained. The predictions are in excellent agreement with numerical results from a 3-D finite element analysis.

Buckling of a Thin Face Layer on Winkler Foundation with Debonds

Abstract: The buckling behavior of a face layer debonded locally from the core of a sandwich panel is analyzed by considering a Euler beam on Winkler foundation with debonds subjected to in-plane compression. Exact closed form solutions of the buckling load and mode shape are obtained, and corresponding numerical results are given to illustrate the solution. Results indicate that the wrinkling wavelength of the perfectly bonded face layer can be used as an appropriate characteristic length for normalizing the debond length of a relatively long face layer. The effects of length and location of debonds and the end constraints of the face layer on the load carrying capacity are discussed. Interactive effects due to two debonds and the overlapping of debond faces are also studied. A master curve based on a classical solution is developed by employing the new normalization of the debond length. A modification to the usual Winkler foundation constants is made for an isotropic core, and it agrees very well with published ...

Sandwich panel of veneer-overlaid low-density fiberboard

Abstract: Low-density sandwich panels of veneer-overlaid fiberboards of 12 mm thickness for structural use were manufactured at densities of 0.3–0.5g/cm3 using an isocyanate compound resin adhesive and steam injection pressing method. The effects of board density, veneer thickness, and resin content on the fundamental properties of sandwich panels were examined, with the following results: (1) The dry moduli of rupture and elasticity in the parallel direction of sandwich panels with thicker veneers were superior. The dry moduli of rupture and elasticity in the parallel direction of sandwich panels with 2.0 mm thick veneer at densities of 0.4–0.5 g/cm3 were 40–60 MPa, and 5–8 GPa, which were two and four times as much as those of homogeneous fiberboards, respectively. (2) The higher-density panels exhibited tensile failure at the bottom veneer surface during static dry bending in a parallel direction, whereas lower-density panels experienced horizontal shear failure in the core. (3) The dimensional stability of sandwich panels had good dimensional stability, with negligible springback after accelerated weathering conditions. (4) The thermal insulation properties of sandwich panels were found to be much superior to other commercial structural wood composite panels.

Method and apparatus for securing a thermoplastic insert within a sandwich panel

Abstract: A method is provided for securing a thermoplastic insert between first and second skin sheets of a sandwich panel using an installation tool to rotate the insert about a central axis. One of the installation tool and insert are provided with a male connection feature and the other is provided with a female connection feature such that the installation tool and insert are axially movable toward and away from each other to engage the male and female connection features without requiring relative rotation. The male and female connection features include mating surfaces offset from the central axis to transmit torque between the installation tool and insert. The insert is magnetically attracted to the installation tool by providing one of the installation tool and insert with a magnet and the other with a magnetic material to be attracted by the magnet. The installation tool and insert are then rotated while force is applied in order to drive the insert into the sandwich panel and to frictionally generate heat to friction weld the insert to the sandwich panel.

Elastic Deflection of Thin-Walled Sandwich Panel

Abstract: Derived expressions of equivalent elastic constants of a truss-core sandwich panel are presented in this paper. The truss-core sandwich panel is similar to conventional sandwich systems, but the panel eliminates most of the attendant problems associated with the fabrication process of conventional sandwich systems. The 3-D trusscore sandwich panel is transformed into an orthotropic thick plate continuum for which 2- D closed-form and 2-D finite element solutions are obtained. Comparison of closed-form solution and finite element results showed good agreement. Using closed-form solution, deflection coefficients are computed and presented in the form of data tables to aid rapid assessment of maximum elastic deflection of truss-core panels; linear interpolation allows the response to be determined, and from which effective preliminary design may proceed without hindrance.

Constructional sandwich panel for high strength wall and covering assemblies, and method for making said panel

Abstract: A sandwich panel for high strength wall and covering assemblies, comprising at least a plate element and at least a fretted element, glued to the plate element, the fretted element comprising a sheet metal plate having a size substantially like that of the plate element and a cross-section having a profile including a plurality of adjoining integral trapezium shape elements each defining a top and a bottom flat portion.

On the Response of a Sandwich Panel with a Bilinear Core

Abstract: Sandwich panels can failin a variety of ways. In the present article one type of failure is investigated and modeled that has a number of important applications, e.g., marine hulls. Here core yielding is assumed to initiate and grow in the sandwich panel while the face sheets remain bonded, unbuckled, and in the elastic range. For elastic face sheets, the core shear stresses can be determined from equilibrium of the face sheets independent of core yield. Core shear strains can then be found from the stress-strain curve and an algorithm is constructed for determining shear deflection. Bending deflection is found from the elastic solution. This approach works well except when the bilinear stress-strain behavior approaches the perfectly plastic core. With the aid of a detailed finite-element solution, it is shown that the classical sandwich theory assumptions begin to break down and that the face sheets now carry an appreciable part of the shear load. This effect is shown in detail for four-point beam bendin...

Experimental Evaluation of Interactive Buckle Localization in Compression Sandwich Panels

Abstract: Experimental observations on an axially-loaded sandwich panel compare well with the recent developments in the theoretical modelling of interactive localized buckling. Comparisons of experimental collapse loads. buckle wavelengths and equilibrium paths With the theoretical model show good correlation.

Designing honeycomb panels for noise control

Abstract: Honeycomb sandwich panels which have similar mechanical properties can have significantly different acoustic properties. The mechanical properties are panel thickness, static bending stiffness and mass per unit area of the panel. The acoustic performance of the panel can be assessed by considering the panel as either a primary radiator of structure borne noise or as a transmission loss barrier. The differences in acoustic performance of the sandwich panels is determined by the bending wave speed characteristic of the panel. The key to designing honeycomb panels for noise control is to maintain a sub-sonic bending wave speed in the sandwich panel over as great a frequency range as possible. The noise control benefits of a properly designed nomex honeycomb sandwich panel are demonstrated relative to alternative non-optimum designs.

Z-shaped strut for door panel

Abstract: A reinforced garage door panel construction comprises a sandwich panel system having inner and outer skins with interconnecting insulating material, a continuous reinforcing strip extending along an inner face of the inner skin and secured to the inner face, a modified “Z” shaped structural member extending substantially the length of the panel and secured to the inner skin at the continuous reinforcing strip by fasteners which extend through the skin and into the continuous reinforcing strip, the modified “Z” shaped structural member having a web with an upstanding front flange and a depending rear flange, the depending rear flange having an inwardly extending lip extending essentially parallel to the web and the depending flange having spaced apart reinforcing beads extending the length of the depending flange.

Sound radiation from a line forced perforated elastic sandwich panel

Abstract: Composite barriers, consisting of thin plates separated by light matrix structures, are widely used for fuselage construction in the aircraft industry, and in partitions in the building trade. The acoustical properties of such materials can vary considerably by altering the interior geometry, and perforations can be added to one or both sides. With perforations the interior cavities can act as Helmholtz resonators, causing a substantial modification to the overall transmission and reflection properties of such barriers. Leppington [Proc. R. Soc. London, Ser. A 427, 385–399 (1990)] devised an effective boundary condition for a perforated sandwich plate structure, valid in the limit of low frequency (acoustical waves long compared with the typical dimensions of the hole/cavity construction), and obtained transmission and reflection coefficients for infinite planar structures. This article investigates the radiation properties of perforated sandwich plates by examining a simple infinite one-dimensional model (employing Leppington’s effective boundary condition) which is loaded by a line force or moment. The radiated far field, and unattenuated subsonic plate wave coefficients, are found explicitly, and are plotted over a range of frequencies for two physical configurations, namely an aluminum plate in water and in air. It is revealed that, unlike the usual thin plate equation, the model discussed herein has two bi-directional unattenuated plate waves, and for the structure in air the two waves are of similar magnitude over most frequencies. Surprisingly, these amplitudes are shown to become very large at a frequency below that of the structure’s Helmholtz resonance frequency. Further, the field radiating into air is also significantly modified by the cavity/perforations well away from the Helmholtz frequency.

Honeycomb sandwich panel

Abstract: PROBLEM TO BE SOLVED: To strongly adhere a skin panel to a honeycomb core and to reduce a porosity in the panel very much by setting a woven fabric METSUKE of a reinforcing fiber woven fabric to a specific value range. SOLUTION: A skin panel is convenient in a production process preferably made of a prepreg or its laminate. In the honeycomb sandwich panel, reinforcing fiber woven fabric has a woven fabric METSUKE of 320 to 500 g/m2. If it is less than 320 g/m2, an exudation of a resin is deteriorated, and fillet formability is deteriorated, and surface smoothness of the panel might be lowered. If it exceeds 500 g/m2, resin impregnability of the resin when the prepreg is manufactured might be lowered. The reinforcing fabric having such a range of the METSUKE is preferable due to contribution to enhance a reducing effect of the manufacturing cost and the efficiency in the manufacturing steps.

Insert fitting method to honeycomb sandwich panel

Abstract: PROBLEM TO BE SOLVED: To provide a manufacturing method of a honeycomb sandwich panel with inserts which can easily maintain high-precision arranging pitch between inserts and flatness between each insert, even when a large number of inserts are fitted. SOLUTION: In a method for fitting inserts to a honeycomb sandwich panel used for a structure such as an artificial satellite or the like, insert-fitting holes 11A are formed on a honeycomb core 11 before it is covered with skins 13 and 14. After the forming of the insert-fitting holes 11A, the skins 13 and 14 are adhered to both surfaces of the honeycomb core 11 by an adhesive 12. Insert-mounting holes are bored in the skin 13 on the side wherein inserts 20 are to be fitted. The inserts 20 inserted from the insert-mounting holes into the insert-fitting holes 11A are suspended and supported by a jig provided so as to be flush with the insert-mounting holes, and a filler S poured into the insert-fitting holes 11A are cured.

Open-die forging of structurally porous sandwich panels

Abstract: Structurally porous metal sandwich panels consisting of dense face sheets and porous cores of controlled relative density can be manufactured by trapping inert gas during hot isostatic pressing and modifying its distribution via subsequent thermomechanical forming. A plane-strain solution for analyzing the open-die forging of such a plastically compressible sandwich panel is developed. An effective yield potential for the face sheet/core sandwich is constructed from the Mises yield criterion for the rigid-plastic face sheet and Doraivelu et al’s density-dependent yield function for the compressible core. This effective constitutive response is used in a classical “slab” analysis of open-die forging. The analysis predicts the upsetting force and the distributions of pressure, core relative density, and average stresses within both the face sheet and the core. During upsetting, a zone of fully constrained material (i.e., with zero lateral strain) is predicted to occur at the center of the workpiece, and this densifies first. A densification front then advances laterally from the panel center toward the outer edges. The nonuniform densification complicates the use of forging for the production of components requiring a uniform density core.

Car for elevator

Abstract: PROBLEM TO BE SOLVED: To reduce the motive power by forming a sandwich panel or a hollow section panel as a structural member of a cage. SOLUTION: A cage 1 of an elevator is formed by five faces, that is, a floor plate 3, a ceiling plate 4, the side plates 5 and a back plate 6, and an openable and closable car door 7 is installed at a front side. The floor plate 3, the ceiling plate 4 and the side plates 5 are formed by a sandwich panel comprising a core material and a skin material made of a plastic sheet, or a hollow section panel using the plastic sheet as the skin material and the stringer, and a part corresponding to a car frame 2 is provided with a reinforcement spur made of these panels to improve the total rigidity and strength of the cage. Accordingly high rigidity and strength can be obtained even when a thickness of the panel is thin, and the weight can be considerably reduced by the effect of the low specific gravity of the material. Whereby the motive power can be reduced, and the car can be easily applied to a home elevator operated by a domestic power source.

Sandwich panel manufacturing method, and sandwich panel obtained thereby

Abstract: PROBLEM TO BE SOLVED: To provide a technology to favorably manufacture a thin and lightweight sandwich panel in a sound brazed condition without degradation in productivity or economy. SOLUTION: An aluminum corrugated core 16 showing a continuous corrugation directed in one direction is held between two aluminum face plates 12 and 14, and the corrugated core 16 and two face plates 12 and 14 are integratedly brazed by an Al-Si brazing filler metal alloy having the composition consisting of, by weight, 6-9% silicon(Si) and the balance Al with inevitable impurities and containing substantially no magnesium(Mg).