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Sandwich-structured composite
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<h2 id="history">History</h2> <p>A summary of the important developments in sandwich structures is given below.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> </p> <ul><li>230 BC <a href="/facts/Archimedes/sIeMhSVF">Archimedes</a> describes the <a href="/facts/Lever/HYDtMuAq">laws of levers</a> and a way to calculate density.</li> <li>25 BC <a href="/facts/Vitruvius/IVnqcSzv">Vitruvius</a> reports about the efficient use of materials in Roman <a href="/facts/Truss_roof/uCqa7zzq">truss roof</a> structures.</li> <li>1493 <a href="/facts/Leonardo_da_Vinci/E83tcPl2">Leonardo da Vinci</a> discovers the <a href="/facts/Neutral_axis/H6rJrjjt">neutral axis</a> and load deflection relation in three-point bending.</li> <li>1570 <a href="/facts/Palladio/Ys2dTuYU">Palladio</a> presents truss-<a href="/facts/Beam_(structure)/V9BPDeS8">beam</a> constructions with diagonal beams to prevent <a href="/facts/Shear_deformation/aU5SgKxL">shear deformations</a>.</li> <li>1638 <a href="/facts/Galileo_Galilei/98VT2z3v">Galileo Galilei</a> describes the efficiency of tubes versus solid rods.</li> <li>1652 Wendelin Schildknecht reports about sandwich beam structures with curved wooden beam reinforcements.</li> <li>1726 <a href="/facts/Jacob_Leupold/eG7MoEup">Jacob Leupold</a> documents <a href="/facts/Tubular_bridges/hbr9m1U9">tubular bridges</a> with compression loaded roofs.</li> <li>1786 <a href="/facts/Victor_Louis/u926gF5L">Victor Louis</a> uses iron sandwich beams in the galleries of the <a href="/facts/Palais-Royal/x19SHlkJ">Palais-Royal</a> in Paris.</li> <li>1802 <a href="/facts/Jean-Baptiste_Rondelet/Sm0BmrcA">Jean-Baptiste Rondelet</a> analyses and documents the <a href="/facts/Sandwich_theory/zok0IDBf">sandwich</a> effect in a beam with spacers.</li> <li>1820 Alphonse Duleau discovers and publishes the <a href="/facts/Moment_of_inertia/TpLLAVl7">moment of inertia</a> for sandwich constructions.</li> <li>1830 <a href="/facts/Robert_Stephenson/bITLIgA1">Robert Stephenson</a> builds the <a href="/facts/Planet_(locomotive)/vt6s43fq">Planet locomotive</a> using a sandwich beam frame made of wood plated with iron</li> <li>1914 R. Höfler and S. Renyi patent the first use of honeycomb structures for structural applications.</li> <li>1915 <a href="/facts/Hugo_Junkers/QqVlgtYc">Hugo Junkers</a> patents the first honeycomb cores for aircraft application.</li> <li>1934 Edward G. Budd patents welded steel honeycomb sandwich panel from corrugated metal sheets.</li> <li>1937 <a href="/facts/Claude_Dornier/GFHXhark">Claude Dornier</a> patents a honeycomb sandwich panel with skins pressed in a plastic state into the core cell walls.</li> <li>1938 Norman de Bruyne patents the structural adhesive bonding of honeycomb sandwich structures.</li> <li>1940 The <a href="/facts/De_Havilland/8JjkbUxV">de Havilland</a> <a href="/facts/De_Havilland_Mosquito/G5BUMHX8">Mosquito</a> was built with sandwich composites; a <a href="/facts/Balsawood/dRIILpVw">balsawood</a> core with <a href="/facts/Plywood/eM5WFvER">plywood</a> skins.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a></li></ul> <h2 id="types-of-sandwich-structures">Types of sandwich structures</h2> <p>Metal composite material (MCM) is a type of sandwich formed from two thin skins of metal bonded to a plastic core in a continuous process under controlled pressure, heat, and tension.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p><p><a href="/facts/Recycled_paper/6DHpr9Aj">Recycled paper</a> is also now being used over a closed-cell recycled kraft honeycomb core, creating a lightweight, strong, and fully repulpable composite board. This material is being used for applications including point-of-purchase displays, bulkheads, recyclable office furniture, exhibition stands, wall dividers and terrace boards.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p><p>To fix different panels, among other solutions, a transition zone is normally used, which is a gradual reduction of the core height, until the two fiber skins are in touch. In this place, the fixation can be made by means of bolts, rivets, or adhesive. </p><p>With respect to the core type and the way the core supports the skins, sandwich structures can be divided into the following groups: homogeneously supported, locally supported, regionally supported, unidirectionally supported, bidirectionally supported.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> The latter group is represented by <a href="/facts/Honeycomb_structure/WbV1SjtX">honeycomb structure</a> which, due to an optimal performance-to-weight ratio, is typically used in most demanding applications including <a href="/facts/Aerospace/T6kTLUyV">aerospace</a>. </p> <h2 id="properties-of--sandwich-structures">Properties of sandwich structures</h2> <p>The strength of the composite material is dependent largely on two factors: </p> <ol><li>The outer skins: If the sandwich is supported on both sides, and then stressed by means of a downward force in the middle of the beam, then the bending moment will introduce shear forces in the material. The shear forces result in the bottom skin in tension and the top skin in compression. The core material spaces these two skins apart. The thicker the core material the stronger the composite. This principle works in much the same way as an <a href="/facts/I-beam/g5HSloVP">I-beam</a> does.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></li> <li>The interface between the core and the skin: Because the <a href="/facts/Shear_stress/aWWnzIhE">shear stresses</a> in the composite material change rapidly between the core and the skin, the adhesive layer also sees some degree of shear force. If the adhesive bond between the two layers is too weak, the most probable result will be delamination. The failure of the interface between the skin and core is critical and the most common damage mode. The propensity of this damage to propagate through the interface or dive either into the skin or core is governed by the shear component.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a></li></ol> <h2 id="application-of-sandwich-structures">Application of sandwich structures</h2> <p>Sandwich structures can be widely used in <a href="/facts/Sandwich_panel/wyPLN7Vg">sandwich panels</a>, with different types such as FRP sandwich panel, <a href="/facts/Aluminium_composite_panel/wyPLN7Vg">aluminium composite panel</a>, etc. FRP polyester reinforced composite honeycomb panel (sandwich panel) is made of polyester reinforced plastic, multi-axial high-strength glass fiber and PP honeycomb panel in special antiskid tread pattern mold through the process of constant temperature vacuum adsorption & agglutination and solidification. </p> <h2 id="theory">Theory</h2> <p class="note">Main article: <a href="/facts/Sandwich_theory/zok0IDBf">Sandwich theory</a></p> <p>Sandwich theory<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a><a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> describes the behaviour of a <a href="/facts/Beam_theory/3DyQV9do">beam</a>, <a href="/facts/Plate_theory/7bCRFl8F">plate</a>, or <a href="/facts/Plate_theory/7bCRFl8F">shell</a> which consists of three layers - two face sheets and one core. The most commonly used sandwich theory is <a href="/facts/Linear/fChtg3KC">linear</a> and is an extension of first order <a href="/facts/Beam_theory/3DyQV9do">beam theory</a>. Linear local buckling sandwich theory is of importance for the design and analysis of Sandwich plates or <a href="/facts/Sandwich_Panel/wyPLN7Vg">sandwich panels</a>, which are of use in building construction, vehicle construction, airplane construction and refrigeration engineering. </p> <h2 id="see-also">See also</h2> Wikimedia Commons has media related to Composite honeycombs. <ul><li><a href="/facts/Sandwich_panel/wyPLN7Vg">Sandwich panel</a></li> <li><a href="/facts/Sandwich_plate_system/5kqQaa6u">Sandwich plate system</a></li> <li><a href="/facts/Composite_honeycomb/WbV1SjtX">Composite honeycomb</a></li> <li><a href="/facts/Honeycomb_Structures/WbV1SjtX">Honeycomb Structures</a></li> <li><a href="/facts/Sandwich_theory/zok0IDBf">Sandwich theory</a></li> <li><a href="/facts/Flitch_beam/qc5VtYfE">Flitch beam</a></li> <li><a href="/facts/Bending/gxA8Pks1">Bending</a></li> <li><a href="/facts/Beam_theory/3DyQV9do">Beam theory</a></li> <li><a href="/facts/Composite_material/UBysQldh">Composite material</a></li> <li><a href="/facts/Hill_yield_criteria/B1DN2MjW">Hill yield criteria</a></li> <li><a href="/facts/Timoshenko_beam_theory/0WXeu3UN">Timoshenko beam theory</a></li> <li><a href="/facts/Plate_theory/7bCRFl8F">Plate theory</a></li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="http://www.sandwichpanels.org/">SandwichPanels.org</a> – Composite sandwich structure information</li> <li><a href="https://web.archive.org/web/20081120190919/http://www.diabgroup.com/europe/literature/e_pdf_files/man_pdf/sandwich_hb.pdf">Diab Sandwich Handbook</a></li> <li><a href="https://www.hexcel.com/user_area/content_media/raw/Honeycomb_Sandwich_Design_Technology.pdf">Honeycomb Sandwich Design Technology</a></li> <li><a href="http://www.dendrolight.lv">Engineered timber sandwich core materials</a> – Composite sandwich structure information</li> <li><a href="https://www.researchgate.net/profile/Mohsen_Amraei/publication/262990667_Application_of_aluminium_honeycomb_sandwich_panel_as_an_energy_absorber_of_high-speed_train_nose/links/576eb8ba08ae62194746bab3.pdf">[1]</a>-Application of aluminium honeycomb sandwich panel as an energy absorber of high-speed train nose</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>EconHP Holding – History without Flash /index.php Archived 2011-07-18 at the Wayback Machine. Econhp.de. Retrieved on 2012-09-06. <a href="http://www.econhp.de/history-without-flash.html" target="_blank">http://www.econhp.de/history-without-flash.html</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Cutler, John Henry; Koppel, Ivan; Liber, Jeremy (10 February 2006). Understanding Aircraft Structures. Blackwell Publishing Limited. p. 14. ISBN 1-4051-2032-0. <a href="1-4051-2032-0" target="_blank">1-4051-2032-0</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Flanagan, Jim (2007). "The Realm of Building Possibilities Created by MCM and Insulated Metal Panels". Metal Construction News. 28 (10). <a href="http://d.wanfangdata.com.cn/NSTLQK_NSTL_QK14842580.aspx" target="_blank">http://d.wanfangdata.com.cn/NSTLQK_NSTL_QK14842580.aspx</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"WPC Terrassendielen" (in German). 1 January 2023. <a href="https://www.wpc-terrassendielen-traumboden24.de" target="_blank">https://www.wpc-terrassendielen-traumboden24.de</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"Sandwich panel classification (by type of core)". EconCore.com. Retrieved 2014-10-07. <a href="http://econcore.com/en/classification" target="_blank">http://econcore.com/en/classification</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Gere, James M (2004). Mechanics of Materials. Thomson Brooks/Cole. pp. 393–463. ISBN 0-534-41793-0. <a href="0-534-41793-0" target="_blank">0-534-41793-0</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Saseendran, Vishnu (2017). Fracture Characterization and Analysis of Debonded Sandwich Composites. Technical University of Denmark. ISBN 978-87-7475-524-1. <a href="978-87-7475-524-1" target="_blank">978-87-7475-524-1</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Plantema, F, J., 1966, Sandwich Construction: The Bending and Buckling of Sandwich Beams, Plates, and Shells, Jon Wiley and Sons, New York. <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Zenkert, D., 1995, An Introduction to Sandwich Construction, Engineering Materials Advisory Services Ltd, UK. <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> </ol>