Endurance of Damping Properties of Foam-Filled Tubes.

Matteo Strano,Valerio Mussi,Alessandro Marra,Massimo Goletti,Philippe Bocher

doi:10.3390/ma8074061

Matteo Strano, Valerio Mussi + Show 3 more

Open Access

https://doi.org/10.3390/ma8074061

Copy DOI

Abstract

The favorable energy-absorption properties of metal foams have been frequently proposed for damping or anti-crash applications. The aim of this paper is to investigate the endurance of these properties for composite structures, made by a metal or a hybrid metal-polymeric foam used as the core filling of a tubular metal case. The results of experimental tests are shown, run with two types of structures: 1) square steel tubes filled with aluminum or with hybrid aluminum-polymer foams; 2) round titanium tubes filled with aluminum foams. The paper shows that the damping properties of a foam-filled tube change (improve) with the number of cycles, while all other dynamic properties are nearly constant. This result is very important for several potential applications where damping is crucial, e.g., for machine tools.

Highlights

The use of parts made of an outer metal case and a core filled with metal foam was frequently proposed in the technical and scientific literature for several applications
According to the results of numerical simulations, the shape of the first two vibrational modes is given in Figure 7 while the related values of natural frequency are about 3640 Hz and 8300 Hz for the tube filled with low-density foam and about 3470 Hz and 8020 Hz for the high-density sample
The tubes studied in this work have a flexural stiffness (EI)tube that is the sum of the one related to the external titanium tube (EI)Ti_skin and the one of the foam filling (EI)foam, considering a perfect coupling between the internal surfaces

Summary

Introduction

The use of parts made of an outer metal case (e.g., a steel tube) and a core filled with metal (e.g., aluminum) foam was frequently proposed in the technical and scientific literature for several applications. Morphology (APM) process developed at Fraunhofer IFAM in Bremen and described in [4,5] are a composite combination of spheroidal aluminum foam pellets, bonded by an epoxy expandable adhesive. They are conveniently used as fillers of large metal structures, because the final foaming operation can be performed at low temperature, reducing potential thermal distortion and softening of the outer case structure [6]. Protection devices benefit from the ability of foam-filled structures to absorb and dissipate mechanical energy in the large strain regime [8], if loaded in compression, bending and torsion (not in tension). In vibrational loading with low amplitude, the mechanical energy is dissipated because of a hysteresis cycle of the material, which in cellular metallic materials is enhanced by localized stresses at the cell walls

Objectives

Methods

Results

Conclusion