EP-4739494-A2 - COMPOSITE SANDWICH PANELS, CORES FOR COMPOSITE SANDWICH PANELS, METHODS OF JOINING PANELS, AND METHODS OF ASSEMBLY

Abstract

A core for a composite sandwich panel, a composite sandwich panel, and a method forming a composite sandwich panel, the composite sandwich panel including a core pic properties and to increase a shear strength density scaling, the core defining a generally planar element having a front side and an opposing rear side, a frame that outlines a perimeter of the core, shims received within the frame and configured to accommodate mechanical fasteners, and a skin composed of a thin material having a high tensile strength, a width sufficient to provide reinforcement for joinery, and where the core includes bonding surfaces that extend generally parallel to the skin and provide increased area contact for enhanced adhesion to the skin.

Inventors

• SILVERBERG, Jesse
• EVANS, ARTHUR

Assignees

• Multiscale Systems, Inc.

Dates

Publication Date

20260513

Application Date

20240607

Claims (1)

1. CLAIMS: 1. A composite sandwich panel, comprising: a core composed of a plurality of intersecting polygonal facets configured to defining a generally planar' element having a front side and an opposing rear side; a frame that outlines a perimeter of the core; shims received within the frame and configured to accommodate mechanical fasteners; and sposed on the front side and the rear’ side of the core; wherein the frame has a width sufficient to provide reinforcement for joinery; and wherein the core includes bonding surfaces that extend generally parallel to the skin and provide increased area contact for enhanced adhesion to the skin. 2. The composite sandwich panel of claim 1, wherein the frame comprises a trough which receives and retains the shims. 3. The composite sandwich panel of claim 2, wherein the trough is delimited by an outer jr of the core, an inner boundary that protrudes from the front side of the core and extends generally collinear with the outer border, and a flat surface on the frame which extends between the outer border and the inner border on the front side of the core. i and continuously with a central region of the core that contains the polygonal facets, and wherein the trough has a generally U-shaped cross-section. 5. The composite sandwich panel of claim 2, wherein the shims comprise one or more 6. The composite sandwich panel of claim 3, wherein the bonding surfaces are disposed on the polygonal facets on the front side and rear side of the core, wherein the bonding surfaces on the front side of the core are coplanar with the inner and outer borders, and ice of the frame formed on the rear' side of the core. 7. The composite sandwich panel of claim 6, wherein the bonding surfaces on the front side of the core are coplanar with one another, and wherein the bonding surfaces on the t side of the core being arranged parallel to the bonding surfaces on the rear side. 8. The composite sandwich panel of claim 7, wherein the bonding surfaces at the front side of the core are connected to the bonding surfaces at the rear side of the core by angled 9. The composite sandwich panel of claim 8 wherein the angled polygonal portions extend from the bonding surfaces at an angle of about one-hundred and thirty-five degrees. d facets extends across the front side of the panel in parallel to one another, wherein a second group of the polygonal facets extends across the front side of the panel in parallel to one another and at an angle to the first group, where the first and second groups intersect at an intersection axis to form a repeating V-shape. 9. The composite sandwich panel of claim 8, wherein the angle of intersection is about one-hundred and thirty-five degrees. 10. The composite sandwich panel of claim 1, wherein the skin material is composed of a thin gauge, high strength steel. 11. The composite sandwich panel of claim 1, wherein the skin material is composed of a 12. The composite sandwich panel of claim 1, wherein the core is designed to have inplane auxetic properties to maximize fatigue life and impact resistance. a plurality of intersecting polygonal facets configured to promote isotropic properties and to increase a shear strength density scaling; and a plurality of bonding surfaces formed on the facets that define an increased contact area for enhanced adhesion to mating surfaces. 14. The core of claim 13, wherein the bonding surfaces comprise surfaces on a front side of the core that are coplanar with one another, surfaces on a rear- side of the core that are coplanar with one another, wherein the bonding surfaces on the front side of the core are arranged parallel with the bonding surfaces on the rear side. 15. The core of claim 14, wherein the bonding surfaces at the front side of the core are connected to the bonding surfaces at the rear side of the core by angled polygonal portions, wherein the angled polygonal portions extend from the bonding surfaces at an angle of about one-hundred and thirty-five degrees. 16. The core of claim 14, wherein a first group of the polygonal facets extends across the front side of the panel in parallel to one another, wherein a second group of the polygonal facets extends across the front side of the panel in parallel to one another and at an angle the first group, where the first and second groups intersect at an intersection axis to form a repeating V- shape, wherein the angle of intersection is about one-hundred and thirty-five degrees. 17. The core of claim 13, further comprising a frame extending around the plurality of r more shims configured to accommodate mechanical fasteners. 18. A method of manufacturing a composite sandwich panel, the method comprising: providing a core composed of a plurality of intersecting polygonal facets; ;rength density scaling of the core; forming bonding surfaces on the facets that provide increased area contact for enhanced adhesion; forming a frame that outlines a perimeter of the core; mechanical fasteners; and disposing a skin composed of a thin material having a high tensile strength on a front side and on a rear side of the core; and adhering the skin to the bonding surfaces. 19. The method of claim 18, further comprising forming a trough in the frame for receiving the shims by protruding an outer border from the front side of the core and extending the outer border around the perimeter of the core, protruding an inner boundary from the front side of the core and extending the inner border generally collinear with the the inner border on the front side of the core. 20. The method of claim 19, further comprising forming the bonding surfaces on the polygonal facets on the front side and the rear side of the core, arranging the ith the inner and outer borders, arranging the bonding surfaces on the rear side of the core coplanar to each other and coplanar with a flat surface of the frame on the rear side of the core, arranging the bonding surfaces on the front side of the core to be parallel with the bonding surfaces on the rear side, and connecting the bonding surfaces at the front side of ins. REFERENCE NUMERALS 10 composite sandwich panel 12 core 16 rear side of core 18 skin 20 interior surface of skin 22 exterior surface of skin 26 frame 28 polygonal facets 30 rear flat surface of frame 32 front flat surface of frame 36 outer border 38 outermost surface of border 40 bonding surface 42-48 shim 52 extension 100 composite sandwich panel 102 protective film 150 composite sandwich panel 154 portion having larger cross-section 200 composite sandwich panel 220 one-part post 222 portion of post 226 connecting portion 250 two-part post 252 first portion 254 second portion

Description

COMPOSITE SANDWICH PANELS, CORES FOR COMPOSITE SANDWICH PANELS, METHODS OF JOINING PANELS, AND METHODS OF ASSEMBLY CROSS REFERENCE TO RELATED APPLICATION nation Serial Number 63/471,699 filed on June 07, 2023, the entire contents of which are herein incorporated by reference. TECHNICAL FIELD more particularly, composite sandwich panels formed from a plurality of materials, a core for such panels, methods of joining, and methods of assembly. BACKGROUND t but strong structure is required, for example, in transport vehicles, shipping containers, etc. Such composite sandwich panels typically utilize a structure comprised of a core of high density polyethylene (HDPE) foam (or other resins) with steel skins (or other high stiffness/strength skins, e.g., aluminum or fiber-reinforced polymers) affixed to the core. agth (i.e. stiffness to weight and strength to weight ratios, respectively), these panels still typically weigh between 70 and 90 pounds in standard configurations, thus adding weight to the resulting structure. This is disadvantageous, particularly in shipping and transportation applications where increases in weight are associated with a rise in fuel consumption, a decrease in freight efficiency, and an overall increase in costs. Alternative materials like lightweight polystyrene (PS) foam or polypropylene (PP) honeycomb can further decrease weight but suffer from several structural drawbacks. Particularly, PS foam has low shear strength and thus fails prematurely. PP honeycomb has issues are of the core requires custom mechanical fasteners to join panels together, thus complicating assembly and correspondingly increasing costs. Some composite sandwich panels utilize cellular core materials. However, these cellular materials, despite being lightweight and cost efficient at large scale, suffer from several dlular cores have utilized honeycomb geometries and open unit cell configurations formed of repeated intersecting polygonal planes, for example, as disclosed in International Patent Application Number PCT/US2021/038932 entitled, “Material with Proisotropic Stress Response Structure”, the content of which is incorporated herein by reference in its 2a that is available for bonding to the flat surface of the skin of a composite sandwich panel. Moreover, these cores are generically composed of flat/polygonal facets, and often require specialized edge fasteners to join the panels together, thus complicating assembly of a corresponding structure. lly sufficient, and which may be assembled and affixed to adjacent panels in a simple and cost efficient manner. BRIEF SUMMARY ibed herein that generally integrates performance enhancing improvements to the central region of the cellular core, in the form of non-developable wall geometry, increased surface area for bonding to skins, and a panel with a solid frame perimeter surrounding the core. In one instance, this design is achieved through a thermoforming process that creates a trough in the perimeter around the cellular core, and solid materials of the same plastic resin arc then placed into the trough. This configuration facilitates robust fastening using conventional, md custom mechanical fastening methods, and provides a reduced weight panel with high structural integrity. In other embodiments, the trough and/or the solid materials placed into the trough may be formed of substances different from each other and/or different from the substance(s) used to form the body of the panel. osed of a plurality of intersecting polygonal facets configured to promote isotropic properties and to increase a shear strength density scaling, the core defining a generally planar element having a front side and an opposing rear side, a frame that outlines a perimeter of the core, shims received within the frame and configured to accommodate mechanical fasteners, and in the front side and the real' side of the core, where the frame has a width sufficient to provide reinforcement for joinery, and where the core includes bonding surfaces that extend generally parallel to the skin and provide increased area contact for enhanced adhesion to the skin. Here, the shear strength density is the quantitative relationship between shear Further provided herein is a core for a composite sandwich panel, including a plurality of intersecting polygonal facets configured to promote isotropic properties and to increase a shear strength density scaling, and a plurality of bonding surfaces formed on the facets that Additionally provided in the present disclosure is a method of manufacturing a composite sandwich panel, the method including providing a core composed of a plurality of intersecting polygonal facets, arranging the facets to promote isotropic properties and to increase a shear strength density scaling of the core, forming bonding surfaces on the facets that provide increased area contact for enhanced adhesion, forming a frame that outlines a perimeter of the core, disposing shims wi