Investigation of Quasi-Static Indentation Response of Inkjet Printed Sandwich Structures under Various Indenter Geometries.

Vishwesh Dikshit,Swee Sing,Wai Yeong,Jun Wei,Arun Nagalingam,Yee Yap

doi:10.3390/ma10030290

Vishwesh Dikshit, Swee Sing + Show 4 more

Open Access

https://doi.org/10.3390/ma10030290

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Abstract

The objective of this investigation was to determine the quasi-static indentation response and failure mode in three-dimensional (3D) printed trapezoidal core structures, and to characterize the energy absorbed by the structures. In this work, the trapezoidal sandwich structure was designed in the following two ways. Firstly, the trapezoidal core along with its facesheet was 3D printed as a single element comprising a single material for both core and facesheet (type A); Secondly, the trapezoidal core along with facesheet was 3D printed, but with variation in facesheet materials (type B). Quasi-static indentation was carried out using three different indenters, namely standard hemispherical, conical, and flat indenters. Acoustic emission (AE) technique was used to capture brittle cracking in the specimens during indentation. The major failure modes were found to be brittle failure and quasi-brittle fractures. The measured indentation energy was at a maximum when using a conical indenter at 9.40 J and 9.66 J and was at a minimum when using a hemispherical indenter at 6.87 J and 8.82 J for type A and type B series specimens respectively. The observed maximum indenter displacements at failure were the effect of material variations and composite configurations in the facesheet.

Highlights

Sandwich panels are widely used in the aerospace industries due to their light weight and excellent strength-to-weight ratios
Theindenter indenterwas was made madetotofully fullypenetrate penetrateinside insidethe thetest testspecimens specimensand andthen thenthe thedamage damagewas wasobserved observedononboth boththe thetop top and bottom side
All the compliance changes and damage were noted during testing

Summary

Introduction

Sandwich panels are widely used in the aerospace industries due to their light weight and excellent strength-to-weight ratios. These sandwich panels are prone to impact and indentation from loading of field vehicles, grits, hail, bird strike and are mainly found in aircraft bodys, aircraft wings, and nacelles. Conventional honeycomb and cellular core structures are manufactured from materials like paperboard, aluminum, polypropylene etc. These structures are engineered using gear presses, extrusion from blocks of extruded profiles and via expansion and corrugation processes. Sandwich cores are made up of composites like glass, Kevlar, carbon and

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