461 Mat.-wiss. u. Werkstofftech. 2012, 43, No. 5 DOI 10.1002/mawe.201200982 Finite element simulation of the macroscopic heat conductivity of syntactic perforated hollow sphere structures Finite-Elemente-Simulation der makroskopischen Wärmeleitfähigkeit von perforierten Hohlkugelstrukturen M. A. Sulong, A. Öchsner This work investigated the thermal properties of a new type of hollow sphere structures. For this new type, the sphere shell is perforated by several holes in order to open the inner sphere volume for a matrix material. The effective thermal conductivity of syntactic (i.e. spheres com- pletely embedded in a matrix) perforated hollow sphere structures in a primitive cubic (PC) arrangement of unit cell models were numerically evaluated for different hole diameters, matrix volume fractions and different base materials. The results are compared to typical con- figurations without perforation. In the scope of this paper, three-dimensional finite element analyses were used in order to investigate these unit cell models. Keywords: Thermal properties / cellular material / porous structure / finite element method / perforated hollow sphere structure / Im Rahmen dieser Arbeit wird die thermische Leitfähigkeit einer neuen Art von Hohlkugelstruk- turen untersucht. Für diese neue Art wird die Kugelschale mittels mehrerer Löcher perforiert, um das innere Kugelvolumen für ein Matrixmaterial zu öffnen. Die effektive thermische Leitfähigkeit von syntaktischen (d.h. Kugeln vollständig in eine Matrix eingebracht), perforierten Hohlkugel- strukturen in einer primitiv-kubischen Anordnung von Einheitszellen ist numerisch untersucht für verschiedene Lochdurchmesser, Volumenanteile des Matrixmaterials und Grundwerkstoffe. Die Ergebnisse werden mit typischen Konfigurationen ohne Perforation verglichen. Im Rahmem dieser Arbeit werden dreidimensionale Finite-Elemente-Analysen verwendet, um die Einheitszel- len zu untersuchen. Schlüsselwörter: Thermische Eigenschaften / zellulares Material / poröse Struktur / Finite-Elemente- Methode / perforierte Hohlkugelstruktur / 1 Introduction Hollow sphere structures (HSS) are lightweight materials within the group of cellular metals (such as metal foams or lotus-type porous materials) where the macroscopic properties can be tail- ored based on many factors such a base material properties, geo- metrical shapes and dimensions and joining technologies. Some general properties which are attributed to cellular metals are the low thermal conductivity, the ability to absorb high amounts of energy at a relatively low stress level, potential for noise control and vibration damping. A combination of these different physi- cal properties opens a wide field of potential multifunctional applications e.g. in automotive or aerospace industry. An early production stage of such perforated hollow sphere structures is shown in Fig. 1. Joining of single hollow spheres can be done by different methods such as sintering, soldering or adhesively bonding and Department of Solid Mechanics and Design, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia – UTM, 81310 UTM Skudai, Johor, Malaysia Corresponding author: A. Öchsner, Department of Solid Mechanics and Design, Faculty of Mechanical Engineering, Universiti Teknologi Malay- sia – UTM, 81310 UTM Skudai, Johor, Malaysia E-mail: andreas.oechsner@gmail.com i 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.wiley-vch.de/home/muw Fig. 1. Single perforated hollow spheres (i by Glatt GmbH, Dresden, Germany). Bild 1. Einzelne perforierte Hohlkugeln (i Glatt GmbH, Dresden, Deutschland).