Finite Element Analysis of Magnetic Field Single-Turn Systems
Modelling of pulsed magnetic systems has extensive application in the optimisation of electromagnetic metal forming as well as in pulsed ultrahigh field generation systems. This paper presents a detailed three-dimensional finite element analysis model to be used in such power systems and compares simulated solutions with accurate experimental data.
A fast and compact θ-pinch electromagnetic flux-compression generator
Ultrahigh magnetic fields up to 300 T (3 MG) have been generated by electromagnetic flux compression using only 63 kJ from a fast capacitor bank to implode aluminium liners, with 14.7 kJ from a slow capacitor bank needed to provide an initial magnetic field. With no initial field present, pulses of magnetic flux density having a time rate-of-change exceeding 3 × 108 T s−1 have been produced and measured, opening the way for a range of dynamic transformer applications. The outcome of the work suggests that, when using fast multi-MA banks, flux compression can be viewed as an alternative to the single-turn coil technique that will move the boundary of the magnetic fields well beyond 300 T without the need for significant additional investments.
Design of reinforced concrete lining in pressure tunnels, considering thermal effects and jointed rockmass
Abstract Jaeger's theory (Jaeger, Rock Mechanics and Rock Engineering , Cambridge University Press, 1972) of the design of the lining for a pressure tunnel applies to a tunnel located in an isotropic, homogeneous and elastic medium. The theory is derived from the elasticity equations for the plane stress condition. In this paper, Jaeger's theory is extended to a plane strain situation. Also included is a discussion of the effects of a uniform increase (or decrease) in the lining temperature, jointed rockmass, cracking of the tunnel lining, and cracking of the rockmass around the opening. Tables are presented for the modulus of subgrade reaction for various rockmass conditions and for rock sharing pressures for various lining conditions. The reduction factor to include the effect of joints in rockmass is derived by the analysis of a numerical model of the lined tunnel by the finite-infinite-interface element method.