Numerical Simulation of Explosively Compacted Powder-In-Tube MgB2 Superconductor

High T-c MgB2 superconductors were fabricated using the ex-situ and in-situ powder in tube (PIT) technique. During treatment, the precursor materials were shock consolidated under high strain-rates using PETN as the explosive medium. After compaction, the superconducting properties of the steel-sheathed MgB2 samples were examined by means of magnetization measurements using a SQUID magnetometer. Bean's critical state model was applied to investigate the critical current density characteristics of the samples at fields up to 5T. The superconducting transition temperature of the specimens was determined by examining the material temperature dependence of magnetisation in zero field cooled (ZFC) and field cooled (FC) states. An assessment of the explosive compaction technique was carried out by simulating the procedure using the LS-DYNA explicit finite element code. The sample is modelled as a porous soil-like material with a customised yield surface. The numerically estimated final product dimensions, porosity and hardness are compared to the experimental results; furthermore, the numerically obtained pressure, temperature and strain rate profiles are used to assess the efficiency of the compaction process for different explosive quantities and powder compositions.