Fracture of nanoceramics with porous structure at shock wave loadings

Abstract

Abstract.Computer simulation techniques are used to investigate the deformation and damage processes taking place in brittle oxide nanostructured ceramics under intense dynamic loading. The pore structure is shown to substantially affect the size of the fragments and the strength of the ceramics. In porous nanostructured ceramics subjected to shock loading, deformation is localized in mesoscopic bands having characteristic orientations along, across, and at ~ 45º to the direction of propagation of the shock wave front. Clusters of nanopores cause the decreasing of the shear strength of nanostructured ceramics. The localized deformation bands may be transformed into mesoscopic cracks. A method is proposed for a theoretical estimation of the effective elastic moduli of ceramics with pore structure without resorting to well-known hypotheses for the relation between elastic moduli and porosity of the materials.

The Features of Fracture Behavior of an Aluminum-Magnesium Alloy AMg6 Under High-Rate Straining

“…The experimental data obtained were used to estimate parameters of the model designed for the description of plastic flow and fracture of FCC-alloys, where the AMg6 alloy belongs [8][9][10][11][12][13]. The numerical values of model coefficients were refined using computer simulation data.…”

Brittle or Quasi-Brittle Fracture of Ceramic Nanocomposites Under Dynamic Loading

“…To study the dynamic strength of UHTC nanocomposites we used the method of multiscale simulation [6][7][8]. The calculated values of residual stresses were used in the simulation of loading of the elementary volume of ZrB 2 matrix nanocomposite under shock wave loadings.…”

Fracture of Coarse-Grained and Ultrafine-Grained Titanium Upon Quasi-Static and Wave-Impact Loading

“…In this case, it was established that fragmentation of the grained structures to the ultrafine-grained state in metals and alloys caused a significant increase in the yield and tensile strengths under quasi-static stretching at temperatures below 0.3·Т melt (T melt is the melting temperature). However, publications on the strength of ultrafinegrained metals and alloys upon dynamic (impact) loading have started to appear only recently (for example, see [8][9][10]). It was established that for some metal materials in the ultrafine-grained state, the tensile strength upon impact loading and quasi-static stretching is higher than for their coarse-grained structure, whereas for other metal materials, on the contrary, it is lower.…”