In-plane and out-of-plane compressive mechanical properties of Nomex honeycombs based on simulation +Suchao Xie1,2,3, *Zhejun Feng1,2,3, and Hui Zhou1,2 1 Key Laboratory of Traffic Safety on Track, Ministry of Education, Central South University, China; 2 School of Traffic & Transportation Engineering, Central South University, China; 3 Joint International Research Laboratory of Key Technology for Rail Traffic Safety, Central South University, China; *Presenting author: 343169905@qq.com +Corresponding author: xsc0407@csu.edu.cn Abstract: The aim of this study is to investigate in-plane and out-of-plane compressive mechanical properties of different types of Nomex honeycombs. For this purpose, the corresponding simulation analysis of mechanical performance was carried out. Honeycomb cell walls were divided into three layers along the thickness direction, namely aramid paper in the middle and phenolic resin coatings on both sides. To establish the three-layer structure in the Shell element, the method of user-defined integration, that is, the method of defining integration in the Integration_shell was used and the defined integration methods were called in Section_shell. In the user-defined integration, the coordinate S and weight factor WF of corresponding integration points were defined according to different layer thicknesses and the corresponding material parameters were designated for each integration point. To guarantee the ideal elastoplasticity of aramid paper, the failure parameters were set to be their maximum values to avoid material failure and ensure plasticity. In comparison, because phenolic resin is an isotropic material, it is not necessary to define the corresponding local coordinates. It is only necessary to set the same values for parameters in each direction and define the specific failure parameters, so as to realise brittle failure. The finite element model takes brittle failure of phenolic resin in tensile or compression processes into account while ensuring that characteristics of the aramid paper inside are incorporated such that the simulation result matches those obtained experimentally. The simulation analysis provide support for mechanical performance data used when researching and applying Nomex honeycombs, while is able to predict the mechanical performance of Nomex honeycombs. Keywords: Nomex honeycomb; in-plane property; out-of-plane property; simulation analysis