The investigation of mechanical behavior of lightweight aluminium foam sandwith (AFS)

Abstract

Demand and interest for the use of porous materials in various applications are rapidly growing by years. Several types of porous materials had been introduced in market todays and one of the well-known types is metal foam. Yet, metal foam itself is weak and to overcome the limitation, sandwich structure had been introduced which is aluminum foam sandwich (AFS). It has many advantages including excellent stiffness to weight ratio is, high energy absorption and most importantly lightweight. There is the need for lightweight material in structural parts for reducing used of energy and eventually reduce fuel consumption. The applications of AFS are automotive, aerospace, shipbuilding and architectural design industries. There were many researchers who had done an investigation on mechanical behavior of AFS. However, a few numbers did a research on open-cell aluminum foam and none of them identify the effect of skin to core thickness ratio, if any. Therefore, this research was conducted to identify the effect of skin to core thickness ratio on mechanical behavior of AFS when loaded under tension and three point bending experimentally with validation of simulation study. AFS specimens were made of open-cell aluminum foam as a core and attached with 6061-0 aluminum skin sheets using epoxy and hardener. Full factorial design of experiment (DOE) was used and repeated three times for each test. Three levels of skin thickness and three levels of core thickness had been used for tensile test. While for three-point bending test, DOE was developed using three levels of skin thickness and two levels of core thickness. Experimental results showed that by increasing skin to core thickness ratio, strength, force and deflection of AFS also increase for both tension and bending. Besides, results show that core thickness play an important role in effecting behavior of open-cell aluminum foam sandwich because of the percentage of porosity of the foam. Increasing foam thickness, will increase percentage of pore which will weaken the sandwich panels. Simulation study was conducted using LS-DYNA software and showed an agreement with experimental result of sandwich panel’s deformation and force-displacement curve. Statistical analysis details show that both models of tensile and three-point test were significant and reliable with ‘Prob > F’ less than 0.05. The optimum skin to core ratio for tensile and three-point bending test were 0.1 and 0.12 respectively. Stiffness to weight ratio of AFS was increasing with higher core thickness. Lastly, stiffness of proposed porous material (open-cell foam) had better stiffness compared to other porous material with more than 40% higher stiffness.