Dynamic stress–strain states for metal foams using a 3D cellular model

Three-dimensional in situ observations of compressive damage mechanisms in syntactic foam using X-ray microcomputed tomography

“…During this damage process, crushed microspheres were piled up in this region. Note that this deformation mechanism is also observed in metallic foams [17].…”

Stress Distribution in Graded Cellular Materials Under Dynamic Compression

“…The classical R-PP-L model has been proven to overestimate the stress behind the front and the shock wave speed because the densification strain is assumed to be a constant locking strain, which is usually too small when the impact velocity is high. In fact, the densification strain increases with the increase of impact velocity for cellular materials under dynamic crushing (Zou et al, 2009;Barnes et al, 2014;Zheng et al, 2014). Thus the results predicted by the R-PH shock model are closer to the FE results.…”

“…Through sensitivity analysis, the optimal cut-off radius defined based on the reference configuration was found to be about 1.5 times of the average cell radius (Liao et al, 2014). In order to exclude the influence of the data oscillation, Zheng et al (2014) averaged the relation between the shock stress and impact time over a certain time interval. For better consistency with the local strain field method, the relation between cross-sectional stress and impact time is averaged herein over a time interval τ, which corresponds to the time when cells in a width of a 1.5 times average cell size is crushed.…”

“…Several shock models and mass-spring models have been proposed to understand the shock wave propagation in cellular materials under dynamic impact, such as the R-PP-L (rate-independent, rigid-perfectly plastic-locking) model (Reid and Peng, 1997), the mass-spring model (Li and Meng, 2002), the E-PP-R (elastic-perfectly plastic-rigid) model (Lopatnikov et al, 2003), the power law densification model and the D-R-PH (dynamic, rigidplastic hardening) shock model . Because the assurance of the repeatability of samples and the measurement of local stress and strain states have not been well solved by experimental techniques, finite element (FE) method has been applied to simulate the dynamic crushing of cellular materials, such as regular/irregular honeycombs (Ruan et al, 2003;Zheng et al, 2005;Liu et al, 2009;Zou et al, 2009;Hu and Yu, 2013) and open-/closed-cell foams Zheng et al, 2014;Sun et al, 2016). The typical features of stress enhancement and deformation localization can be appropriately represented.…”

Strain rate effect on the out-of-plane dynamic compressive behavior of metallic honeycombs: Experiment and theory

“…The progressive buckling was started from the layers near the interface between the lower platen and the honeycomb specimen, and then induced the deformation of adjacent layers to form folds. In fact, the onset of this progressive buckling can occur anywhere in the specimen where the weakest zone located [6,47].…”