Investigation of the mechanical behavior of a graded cellular rod under impact

• Main Author: Tang, Irving Wei Han.
• Other Authors: Lu Guoxing
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/53542
• Institution: Nanyang Technological University

This report documents the investigation of the behavior and the underlying mechanism of cellular rod with graded cross-sectional area under dynamic loading. Theoretical finite element (FE) simulations and physical experiments were carried out for comparison. A gradient in the cross-sectional area is introduced to a cellular rod along the axial axis. General solutions have been derived for mechanical properties of cellular rods, based on the rigid-perfect plastic-locking (R-PP-L) material model. Aluminum foam was used in both FE simulations and physical experiment. A quasi-static loading test was conducted to obtain the stress-strain relationship for the aluminum foam used. The mechanical properties obtained from the stress-strain relationship were used to model the finite element simulation using ABAQUS. The results showed that two different deformation modes were observed. A double shock (DS) mode was observed when the gradient introduced was negative. The DS mode refers to the phenomenon where deformation zones were observed at both ends of the foam. A single shock (SS) mode was observed when the gradient introduced was positive. In SS mode, deformation only occurred at the impinged end of the foam. The effect of the gradient on the energy absorption is also investigated. Experiments were carried out to observe the phenomenon of DS mode. FE simulation was done to follow as closely as possible the dynamic loading conditions of the experiment. The purpose of the FE simulation was to observe the accuracy of the model and to extend the investigation to beyond the limits of the experiment. The results obtained from both experiment and FE simulation are fairly conclusive.