Experimental investigation of 3D-printed auxetic core sandwich structures under quasi-static and dynamic compression and bending loads

Abstract

Auxiliary metamaterials designed according to the Negative Poisson’s Ratio (NPR) property are exciting structures due to their high impact strength, impact energy absorption abilities, and different damage mechanisms. These good mechanical features are suitable for aviation, automotive, and protective construction applications. These structures, whose most significant disadvantages are production difficulties, have become easier to produce with the development of 3D production technology and have been the subject of many studies in recent years. In this presented study, two conventional core geometries and three different auxetic geometries, commonly used in sandwich structures, were designed and produced with 3D printer technology. The strength and energy absorption capabilities of prototype sandwich structures investigated experimentally under bending loads with static and dynamic compression. Except for the re-entrant (RE) type core, the auxetic core foam sandwich structures demonstrate higher rigidity and load-carrying capacity than classical sinusoidal corrugated (SC) core and honeycomb (HC) core sandwich structures under both quasi-static and impact-loaded compression and three-point bending experiments. Double arrowhead (DAH) and tetrachiral (TC) auxetic cores outperformed honeycomb core in terms of specific quasi-static and impact load-bearing performance under compression by 1.5 ± 0.25 times. In three-point bending experiments under both quasi-static and impact loading conditions, the load-carrying capacity of the double arrowhead and tetrachiral auxetic cores was found to be more than 1,86 ± 0.38 times that of the honeycomb core sandwich panels.

Experimental Investigation of Crush Energy Absorption and Strength Properties of Sandwich Plates With Aluminum Facesheet/ Expanded Polypropylene Foam Core

“…But making comparisons with this value alone will not be enough. There are other criteria that must be considered in automotive crash energy absorber elements (Türkoğlu, et al 2022). These criteria can be briefly summarized as follows;…”

“…However, especially in the automotive industry, when examining the mechanical properties of structures with crash energy absorption potential, material behavior under dynamic loading conditions as well as quasi-static loading conditions is of great importance. Many engineering materials can exhibit different behaviors depending on the speed of the applied force; and this is called 'strain-rate dependency' (Türkoğlu, et al 2022). In this study, both aluminum and EPP foam materials, which form the face plates and core structure of sandwich structures, are strain-rate dependency materials.…”

Reinforcement of 3D‐Printed Re‐Entrant Structures using Additional Supports under Three‐Point Bending, Experimental and Numerical Analyses

“…[68] Türkoglu et al compared the bending performance of two conventional and three different auxetic geometries produced with 3D printer technology. [69] In another research, the bending behavior of 3D-printed structures with adjustable hexagonal, truss, and re-entrant cores was investigated. [70] In a separate study, the bending behavior of sandwich beams with hexagonal, re-entrant, and chiral lattices was studied.…”

An easy-to-implement self-healing smart design for increasing impact strength and crashworthiness resistance of honeycomb sandwich structures

“…[1][2][3][4] Sandwich constructions with aluminum honeycomb cores, on the other hand, remain one of the most significant industrial options due to their static and dynamic mechanical properties, their optimal form, and easy availability due to well-established production methods. [5][6][7][8][9][10][11][12][13][14][15] Damage to structural materials caused by mechanical, thermal, and chemical processes significantly influences their performance, durability, and service life. Therefore, bio-inspired self-healing materials have been designed to repair the damage.…”