Three-Point Bending Fatigue Behavior of Aluminum Foam Sandwich Panels with Different Density Core Material

Cheng Yao,Fan Mo,Zhengfei Hu

doi:10.3390/met11101542

Abstract

The monotonic and fatigue strength of adhesively bonded aluminum foam sandwich panels with different densities of core aluminum foam (0.3 g/cm3, 0.4 g/cm3, 0.6 g/cm3) were investigated in three-point bending tests to study the flexural fatigue behavior of aluminum foam sandwich panels. The force cycle curves, deflection curves, and hysteretic curves are presented to describe the fatigue process of aluminum foam sandwich panels. Their fatigue fracture modes are completely different, the failure modes of the low-density cores (0.3 g/cm3, 0.4 g/cm3) are debonding and face fatigue, whereas the failure mode of the high-density core (0.6 g/cm3) is face fatigue without debonding. The reason is that high-density aluminum foam cores with lower porosity have a larger joining face, which can also provide higher strength and lead to a longer fatigue life.

Highlights

Metallic foams have many outstanding physical and chemical properties, such as low density and a high specific strength, which impact energy absorption, flame resistance, and electromagnetic shield effectiveness [1,2,3,4,5,6,7,8]
Aluminum foam sandwiches, which are fabricated by sandwiching a thick aluminum foam as a core material between two thin alloy sheets as facing sheets, are a special class of composite materials widely used for panels, shells, tubes, crash protection devices, and lightweight structures [12,13]
When low fatigue strength material is used as the face sheet, the endurance limit of the sandwich beam is set by the face fatigue strength

Summary

Introduction

Metallic foams have many outstanding physical and chemical properties, such as low density and a high specific strength, which impact energy absorption, flame resistance, and electromagnetic shield effectiveness [1,2,3,4,5,6,7,8]. The alloy sheets in the sandwich structure can provide specific strength and better dimensional stability than the aluminum foam itself, because the core aluminum foam bears the shear load while the face sheets carry an axial load and resist against bending [14,15,16] Contributions in this field include a study by Burma and Zenkert [17] in 1997 which analyzed the fatigue strength of sandwich structures with PVC cellular cores and fiber-reinforced composite face sheets. Hart et al [18] studied the tension–tension and compression–compression cyclic properties of open-cell and closed-cell aluminum alloy foams, finding that the fatigue ratio is almost independent of the mean stress and the relative density of the foam They [19] proposed a plastic collapse failure mode for aluminum foam sandwich panels and presented a design map to display the fatigue strength and mode of failure as a function of aluminum foam sandwich geometry. The results, including force cycles and hysteretic curves, reflects the differences in behavior between different core materials

Materials and Methods

Deflection

Fatigue Fracture Morphology

Stiffness Degradation

Conclusions