Computational homogenization of the elastic and thermal properties of superconducting composite MgB2 wire

Magnetic Resonance Imaging (MRI) background magnets are made from superconducting composite wires that are a metal matrix composite (MMC). Thermal and mechanical properties of the specific wire matrix must be known to optimize the wire configuration for MRI magnet designs. Computational analysis techniques based on numerical homogenization may provide an accurate characterization of a multifilament MMC wire and can reduce the expenses and time required for experimental tests. Recent developments in magnesium diboride (MgB2) superconducting wire has demonstrated their feasibility in a liquid helium (LHe) free conduction-cooled MRI magnet. Computational analysis of an entire superconducting magnet design requires the elastic and thermal properties of these wires. In this work, the temperature dependent elastic modulus, Poisson's ratio, thermal expansion coefficients, thermal conductivity, and specific heat are estimated using Finite Element Analysis (FEA) and compared to analytical approaches. The orthotropic elastic and thermal properties of four different superconducting composite wire configurations are evaluated. The experimental thermal conductivity and specific heat at room temperature agree well with its corresponding computational results. FEA based computational homogenization has been demonstrated as an acceptable method to estimate the required material properties of the MMC superconducting wire for magnet analysis of MRI manufacturing and operation.