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Mechanical behavior of syntactic Fe-36Ni foams under monotonic and cyclic loading conditions

Mechanisches Verhalten von syntaktischen Fe-36Ni-Schäumen bei monotonen und zyklischen Belastungsbedingungen
: Poltersdorf, P.

Deutsche Gesellschaft für Materialkunde e.V. -DGM-, Oberursel:
Cellular Materials. Proceedings. CD-ROM : 7-9 November, 2012, Dresden; CELLMAT 2012
Dresden, 2012
ISBN: 978-3-00-039965-7
5 S.
International Conference on Cellular Materials (CELLMAT) <2, 2012, Dresden>
Fraunhofer IFAM ()

The porosity in syntactic foams is created by hollow particles of different materials, sizes and shapes. Similar to conventional foams, syntactic foams show distinguished damping and energy-absorption properties. The latter is due to the existence of a stress-plateau after the quasi-elastic regime in the stress-compression behavior. In comparison to other foams, syntactic foams may show very high compression strengths and plateau stresses which allow their application as crash energy absorption elements in very limited volumes. Necessities for such can be found near fasteners, hinges or other joints not only in automotive structures but also in other crash relevant structures like high-speed rotary pumps. Syntactic metal foams consist of a minimum of three phases (compact matrix, pores, wall material of the hollow particles) which leads to a very complex material behavior as demonstrated in quasi-static deformation tests of Fe and Fe-Ni-foams. In order to strengthen the market penetration of this material, syntactic foams have been evaluated with respect to the mechanical behavior with special focus on its fatigue behavior. The present paper gives an overview on the properties of syntactic foam with a Fe-36Ni matrix and different weight fractions of S60HS glass hollow particles (0%, 5% and 10%), and presents first results of the cyclic loading behavior of these materials. The quasi-static experiments under compressive load verified the excellent energy absorption properties with strength and plateau stress decrease with increasing fraction of hollow particles. The first results of load controlled compression fatigue tests (tests were terminated when reaching 106 cycles or when exceeding a displacement of 3 mm) showed a surprisingly high strength of foams with medium sphere content. Syntactic foams with a high fraction of hollow spheres revealed in comparison a stepwise shear collapse during cycling at stress level close to the plateau strength.