Papers by Author: Md Anwarul Hasan

Abstract: Nanoindentation data measured on the cell-wall of Al-alloy foams were analyzed to obtain the material properties of the cell wall. Using the obtained material properties, stress-strain curve of the foam in uniaxial compression was constructed by finite element modeling. The model developed for the analysis was a multiple cell model which utilized the unit cells as the basic building block of the foam. Both the in-plane and through-thickness density variations of the foam were considered in the model. The through-thickness density variation which is a function of casting or foaming process was represented using different densities for different foam layers, while the in-plane density variation which arises from internal defects (such as porosities, second phase particle, inclusions etc.) was assumed to follow a statistical probability distribution of Gaussian type. Uniaxial compression test was performed and the finite element analysis result was compared with the experimental result. The numerical model used in the study overpredicted the crushing strength of foams indicating that the model needs to be improved for predicting the real foam properties with better accuracy.

Abstract: Nanoindentation test has been performed to characterize the mechanical properties of aluminium alloy foam cell wall. Two of the mechanical properties: hardness and Young’s modulus of cell wall material were evaluated using the stiffness of contact during both loading and unloading. Properties obtained from unloading stiffness were in better agreement with the conventional test result than those obtained from loading stiffness. The finite element analysis using nonlinear finite element code ABAQUS was performed to characterize the yield strength and the stress-strain curve of the cell wall material of the foam. Properties of foam cell wall material were found to be substantially different from the properties of the material before foaming. The methodology used in this paper can be effectively used to characterize the mechanical properties of cell wall of any cellular material.