Study of the quasi-static indentation loading of 3D-printed honeycomb based sandwich structured composites
Nagalingam Arun Prasanth
Date of Issue2017-03-27
School of Mechanical and Aerospace Engineering
The objective of this research is to predict the Quasi-static indentation response and damage in three-dimensional (3D) printed honeycomb based structures, and to characterize the energy absorbed by the structures. In this work, the honeycomb sandwich has been designed in the following three ways. Firstly, honeycomb core along with its facesheet is 3D printed as a single element comprising of same material for both core and facesheet. Secondly, advanced honeycomb core along with facesheet is 3D printed, but with variation in facesheet materials which act as composite plies and lastly, honeycomb core and fibre facesheet are 3D printed separately and joined together using adhesive. Quasi-static indentation is carried out using three different indentors, namely standard hemispherical, conical and flat indentors. Acoustic emission (AE), a non-destructive testing (NDT) technique, is used to detect the exact cracking time and the number of hits in the specimens during indentations. After the experiments were conducted, finite element analysis (FEA) was also carried out using ABAQUS/EXPLICIT for one quarter of the specimen size. Symmetric boundary conditions were used in the FEA. The FEA analysis and experimental results were compared and discussed. Results have been discussed based on effect of the honeycomb design used, the influence of different indentor shapes during indentation, and effect of the type of material used. Results showed that when specimens were loaded under flat indenter, there was a higher indentation resistance and force values were high, this also led to higher energy absorption of the specimen. Specimens with single material and multimaterial combination in facesheet almost showed similar behavior, expect the fact that displacement was higher for multimaterial combination. As a result of experimentation, honeycomb structures with fibre facesheet proved to withstand higher force with a higher displacement and high energy absorption characteristics.