Compressive Behaviour of Closed-Cell Aluminium Foam at Different Strain Rates.

Closed-cell aluminium foams were fabricated and characterised at different strain rates. Quasi-static and high strain rate experimental compression testing was performed using a universal servo-hydraulic testing machine and powder gun. The experimental results show a large influence of strain rate hardening on mechanical properties, which contributes to significant quasi-linear enhancement of energy absorption capabilities at high strain rates. The results of experimental testing were further used for the determination of critical deformation velocities and validation of the proposed computational model. A simple computational model with homogenised crushable foam material model shows good correlation between the experimental and computational results at analysed strain rates. The computational model offers efficient (simple, fast and accurate) analysis of high strain rate deformation behaviour of a closed-cell aluminium foam at different loading velocities.

Performances of different subset shapes and control points in subset-based digital image correlation and their applications in boundary deformation measurement.

Digital image correlation (DIC) is an effective and popular tool for displacement and strain measurements. In the standard subset-based algorithms, the center point of a subset is considered by default as the control point for calculation, and it is difficult to obtain the deformation information at the boundary. Proper selection of the subset shape and the location of control points are vital to the displacement calculation at the boundary. In this paper, registration accuracies of several typical types of subset shapes and different locations of control points are investigated. The results illustrate that different choices of subset shapes can greatly affect the registration accuracy, while different choices for the locations of control points have little impact on it. Based on these results, the noncentral algorithm is developed for the whole-field deformation measurement.