The strain rate effect of an open cell aluminum foam
ABSTRACT The dynamic compressive behavior of an open-cell commercially pure aluminum foam was experimentally investigated with a split
Hopkinson bar (SHPB) and numerically simulated using the finite element (FE) method. It is found that the flow stress increases
with increasing strain rate, demonstrating the existence of strain rate dependence in the present aluminum foam. This dependence
is believed to originate from the polygonal pore architecture, the relatively high density, the intrinsic property of aluminum,
as well as the friction force between the contacted cell walls.
Article: Split Hopkinson pressure bar multiple reloading and modeling of a 316 L stainless steel metallic hollow sphere structure[show abstract] [hide abstract]
ABSTRACT: The high strain rate (600 s−1) compression deformation of a 316 L metallic hollow sphere (MHS) structure (density: 500 kg m−3; average outer hollow sphere diameter: 2 mm and wall thickness: 45 μm) was determined both numerically and experimentally. The experimental compressive stress–strain behavior at high strain rates until about large strains was obtained with multiple reloading tests using a large-diameter compression type aluminum Split Hopkinson Pressure Bar (SHPB) test apparatus. The multiple reloading of MHS samples in SHPB was analyzed with a 3D finite element model using the commercial explicit finite element code LS-DYNA. The tested MHS samples showed increased crushing stress values, when the strain rate increased from quasi-static (0.8 × 10−4 s−1) to high strain rate (600 s−1). Experimentally and numerically deformed sections of MHS samples tested showed very similar crushing characteristics; plastic hinge formation, the indentation of the spheres at the contact regions and sphere wall buckling at intermediate strains. The extent of micro-inertial effects was further predicted with the strain rate insensitive cell wall material model and with the strain rate sensitive behavior of MHS structure similar to that of the cell wall material. Based on the predictions, the strain rate sensitivity of the studied 316 L MHS sample was attributed to the strain rate sensitivity of the cell wall material and the micro-inertia.International Journal of Impact Engineering 06/2009; · 1.70 Impact Factor