Analysis and Modeling of Semi-Open Thermoplastic Honeycomb Core Structures for Mechanical Simulation with Representative Volume Elements

Due to the need for alternative materials for the realization of lightweight structures, the analysis of sandwich structures that have a semi-open thermoplastic honeycomb core as an internal support structure is of great technical and scientific interest. Sandwich components with a honeycomb-structured core layer between two continuous fiber-reinforced face sheets exhibit maximum weight-specific stiffnesses and strengths. The folded thermoplastic honeycomb cores have some characteristic properties not found in conventional honeycomb cores due to their special production, which causes the semi-open structure. As a result of the folding process, the cell walls of the honeycombs are not joined together in the folding direction, as would be the case, for example, with glued or expanded honeycombs. This specificity has a great influence on the structural mechanical behavior of the honeycomb. To characterize the mechanical material properties, one possibility is to examine the honeycomb structure based on data obtained by the computed tomography method and, building on this, to analyze these properties in more detail by means of modeling a representative volume element that reflects the cell geometry of the honeycomb core as closely as possible. The aim of this approach is to determine effective material parameters that can be applied to mechanical simulation using the finite element method. The validation of these characteristic values was carried out based on results that can be obtained through standardized, mechanical, quasi-static experiments.