Dynamic uniaxial crushing of wood

High strain rate compressive behaviour of aluminium alloy foams

“…They found that wood loaded along the grain has a softening quasi-static response suggestive of a Type II structure. For velocities in the range of 30}300 m s\ the dynamic crushing strength along the grain is about 2.3 times the static strength, see for example Reid and Peng [13]. They argue that this elevation is due to micro-inertia in the manner observed for a Type II structure.…”

“…They argue that this elevation is due to micro-inertia in the manner observed for a Type II structure. On the other hand, Reid and Peng [13] found a negligible increase in the dynamic transverse strength of woods due to micro-inertia e!ects. This is consistent with the observation that the transverse compressive response is that of a Type I structure under quasi-static loading.…”

Stress Distribution in Graded Cellular Materials Under Dynamic Compression

“…Significant enhancement of crushing stress was observed in the dynamic impact experiments of woods (Reid and Peng, 1997;Harrigan et al, 2005), aluminum honeycombs (Zhao and Gary, 1998;Hou et al, 2012) and foams (Mukai et al, 1999;Deshpand and Fleck, 2000;Tan et al, 2005a;Elnasri et al, 2007). 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 .…”

“…However, the local stress cannot be calculated in a similar manner and the mission of calculating the local stress field for cellular materials seems to be impossible. Fortunately, it was observed that the propagation of shock wave is in a nearly one-dimensional form when cellular materials are crushed under high-velocity impact (Reid and Peng, 1997;Ruan et al, 2003;Tan et al, 2005a;Zou et al, 2009;Liao et al, 2013) and the one-dimensional approximation is popularly used. Thus, we can focus on the one-dimensional stress distribution and use the force on the cross section of cellular material to calculate the cross-sectional stress.…”

“…For simplicity, the shock wave speed is directly calculated from the R-PP-L shock model (Reid and Peng, 1997;Liao et al, 2013), i.e. Vs = V/ε L , where ε L is the locking strain, which is defined as the strain when the maximum value of the energy absorption efficiency function reaches (Tan et al, 2002;Tan et al, 2005).…”