In-plane and out-of-plane compressive mechanical properties of Nomex honeycombs and their prediction
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(2020) 42:460
TECHNICAL PAPER
In‑plane and out‑of‑plane compressive mechanical properties of Nomex honeycombs and their prediction Suchao Xie1,2,3 · Zhejun Feng1,2,3 · Hui Zhou1,2 · Da Wang1,2,3 · Wen Ma1,2,3 Received: 4 May 2020 / Accepted: 3 August 2020 © The Brazilian Society of Mechanical Sciences and Engineering 2020
Abstract Based on experiments used to evaluate the in-plane and out-of-plane mechanical properties of Nomex honeycomb, the influences of different cell geometries and honeycomb densities on the mechanical properties of honeycombs were investigated. The content of each component of honeycomb was analysed by disassembly. Furthermore, by introducing the wall thickness ratio and a correction function, a theoretical prediction model of out-of-plane mechanical properties was constructed. As for the prediction of in-plane mechanical properties, a three-layer structural finite element model of the cell walls was established through the use of a user-defined integration method. Keywords Nomex honeycomb · In-plane · Out-of-plane · Prediction method · Three-layer structure List of symbols d Cell size of Nomex honeycomb ts , td Thickness of single and double cell walls h Side length of the double cell wall l Side length of the single cell wall θ Cell wall angle of Nomex honeycomb 𝜎 , 𝜀 Compressive stress and strain of Nomex honeycomb 𝜎c , 𝜀c Collapse stress and strain of Nomex honeycomb 𝜎p Plateau stress of Nomex honeycomb 𝜎ci , 𝜎pi Initial theoretical value of collapse stress and plateau stress 𝜎cc , 𝜎pc Corrected theoretical value of collapse stress and plateau stress
Technical Editor: João Marciano Laredo dos Reis. * Suchao Xie [email protected] 1
Key Laboratory of Traffic Safety on Track, Ministry of Education, Central South University, Changsha 410075, China
2
Joint International Research Laboratory of Key Technology for Rail Traffic Safety, Central South University, Changsha 410075, China
3
School of Traffic and Transportation Engineering, Central South University, Changsha 410075, China
Ea , Em Energy absorption and specific energy absorption of Nomex honeycomb 𝜇 Residual rate of Nomex honeycomb 𝜌n , Sn Equivalent density and cell area of Nomex honeycomb 𝜌∗a , 𝜌∗p Equivalent density of Nomex paper (without resin coating) and resin honeycomb 𝜌a , 𝜌p Density of Nomex paper (without resin coating) and resin Sa∗ , Sp∗ Cell area of Nomex paper (without resin coating) and resin honeycomb Sa , Sp Cell wall area of Nomex paper (without resin coating) and resin honeycomb ta , tp Wall thickness of Nomex paper (without resin coating) and resin honeycomb p Wall thickness ratio Pcs , Pcd Collapse load of the single and double cell walls Es Young’s modulus of cell wall material K End constraint factor H Sample height m , n Half wave numbers in axial direction and transverse direction C(x), G(x) Correction function Q1 , Q2 , Q3 Mechanisms of plastic deformation Ms , Md Fully plastic bending moment of the single and double cell wall 2𝛿 Wavelength of the folding mode r
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