Journal of Materials Processing Technology 214 (2014) 571–577 Contents lists available at ScienceDirect Journal of Materials Processing Technology jou rn al hom epage: www.elsevier.com/locate/jmatprotec Compressive properties and energy absorption of aluminum foams with modified cellular geometry P. Pinto ∗ , N. Peixinho, F. Silva, D. Soares CT2M – Centre for Mechanical and Materials Technologies, Minho University, Azurém, 4800-058 Guimarães, Portugal a r t i c l e i n f o Article history: Received 2 September 2013 Received in revised form 7 November 2013 Accepted 8 November 2013 Available online 17 November 2013 Keywords: Aluminum foam Prototype Compressive properties Energy absorption a b s t r a c t This study presents experimental results on the behavior of aluminum alloy metal foams with controlled pore morphology in compression. Two types of metal foams were analyzed, having uniform cell structure and with a dual-size cell arrangement seeking optimized mechanical properties. The structures were manufactured by lost-wax casting using 3D printed components for internal structure definition. Results for stiffness and energy absorption were obtained and compared on weight efficiency basis. The results are indicative of higher efficiency of the dual-size structures that may be considered for use in components subjected to impact or compression loading. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Metallic foams emerge as a new range of materials with great potential due to its excellent strength-density ratio which presents advantages for the development of components for the transporta- tion industry, such as the automobile sector. In these industries, high energy absorption capacity combined with low density are interesting properties for use in stiffness related parts and passive safety structures (Banhart, 2001; Gibson and Ashby, 1988). Reducing vehicle weight is a major factor in the transport industry since it allows reducing fuel consumption. However, the decrease in vehicle weight cannot reduce passenger safety meaning that the materials used in the manufacturing cannot compromise stiffness and strength. Thus, it is important to correctly determine the behavior and properties of new materials to be used in vehicles (Song et al., 2005). Due to its low density, high strength and excellent energy absorption in compression, the use of metal foams in impact- related parts has been increasingly considered in order to increase passive safety. Due to this excellent performance, there is a need for continuous improvement and to refine their manufacturing processes and production, in addition to the need to characterize mechanically (Banhart and Baumeister, 1998, 2000). ∗ Corresponding author at: Universidade do Minho, Centre for Mechanical and Materials Technologies (CT2M), Campus Azurém, P-4800-058 Guimarães, Portugal. Tel.: +351 253510732. E-mail address: paulopinto@dem.uminho.pt (P. Pinto). The mechanical behavior of metal foams depends on the struc- ture of cells, density and properties of the base material they are made. The efficiency obtained in the use of metallic foams in structural applications requires a detailed characterization of its deformation behavior for different loads and different geometries. The size and shape of the cells or pores determines their properties, namely their behavior depends on how the solid is distributed in the porous structure (Olurin et al., 2000). Advances in material and geometry characterization are required in order to develop mate- rial models suitable for reliable and efficient numerical simulation of the mechanical behavior of foams (Zaiser et al., 2013; Saadatfar et al., 2012). Although the relative density is the most dominant factor in determining the behavior and strength of a metal foam, other parameters such as distribution and configuration of the cells can also have great influence on the mechanical behavior. In a numer- ical simulation study Kou et al. (2008) proposed two types of open-cell foam structures using uniform and dual-size base cell configurations (Fig. 1). Uniform cell metal foams have a spherical shape and are closely compact. It is assumed that the cellular struc- ture has a face-centered cubic arrangement. Dual-size foams have fillers forming a secondary link that is disposed in voids existing in uniform foam (Fig. 1). The distance between two adjacent centers of large fillers is a, the radius of large fillers and secondary fillers are R and r, respectively (Kou et al., 2008). According to the authors, the behavior of foams with dual-size structures is improved regarding uniform structures. It was found in their numerical study that the yield strength of a foam cell structure with dual-size is considerably higher than in a foam with uniform cell structure, for an equivalent density. 0924-0136/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jmatprotec.2013.11.011