Dynamic Properties of Al-Alloy Foam Beam Damaged by Compressive Fatigue

Abstract

The permanent residual strain in aluminum (Al) alloy foams induced by compressive fatigue gradually increases with the increasing number of loading cycles. Consequently, the progressive shortening of Al-alloy foam degrades the dynamic material performance by the failure and ratcheting of multi-cells in the foam. In this paper, the dynamic properties of Al-alloy foams damaged by compressive fatigue were studied. The beam specimens with various residual strains were made by cyclic compression-compression stress. The dynamic bending modulus and loss factor were evaluated by using a beam transfer function method. As a result, the dynamic bending stiffness of Al-alloy foam turned out to be decreased due to damage while the loss factor was improved because of the increasing energy dissipation of such factors as cracked cell walls formed during the shortening process of the foam. The loss factor shows a manifest dependence on the fatigue residual strain.

Molecular statics study of depth-dependent hysteresis in nano-scale adhesive elastic contacts

“…Both works showed that the surface undulations could create surface mechanical instabilities and consequently lead to an effective toughening of the contact interface. The mechanism through which small-scale roughness gives rise to DDH in the work of Kesari et al [25,31] is the same as the mechanism through which the undulations cause adhesive toughening in the work of Li and Kim [32] and Guduru [33].…”

“…Kesari et al [25,31] reported an alternate, new mechanism for DDH in which DDH emerged as the smeared out effect of a series of small-scale surface imperfection created mechanical instabilities (SIMI) that take place at the growing and the receding edges of the contact interface. Their work is related to the works of Li and Kim [32] and Guduru [33]. Li and Kim [32] considered the adhesive contact problem between two solids, in which one of them was an elastic half-space and the other was a rigid solid with two-dimensional sinusoidal undulations on its surface.…”

“…Their work is related to the works of Li and Kim [32] and Guduru [33]. Li and Kim [32] considered the adhesive contact problem between two solids, in which one of them was an elastic half-space and the other was a rigid solid with two-dimensional sinusoidal undulations on its surface. Guduru [33] considered the JKR-type adhesive contact between an elastic half-space and a rigid paraboloidal punch with superimposed sinusoidal undulations.…”

Fabrication and compressive behaviour of an aluminium foam composite

“…Both of them exhibit similar mechanical behavior [25]. There are many test methods, three-point bending [26], impact [27], torsion [28], tensile [29], fatigue [30], compression [31], for mechanical properties of metallic foams. The compression test is the most commonly used for characterizing the mechanical properties of metallic foams.…”