Large-Deformation Response of Deep Circular Arches to Radial Magnetomotive Forces

Abstract

Circular-arch specimens were produced from aluminium rings. By using suitable rigid inserts in a ring, only a small portion of it was allowed to deform freely. The rings were subjected to uniformly-distributed, radially-inward-directed impulsive forces. The forces were generated by a high-energy electrical discharge through a single-turn coil which surrounded the ring. The induced currents in the ring were high enough to engender large, transient, radially-directed magnetomotive forces which caused gross plastic deformation. The elastic–plastic response of the arches was predicted by using a finite-difference numerical technique to solve the equations of motion. The analysis allows for circumferential and shear forces, as well as large changes in geometry. It also incorporates strain-hardening, but it ignores the influence of rotary inertia. High-speed photographs were used to record the transient shape of the collapsing arches. These were found to be in good agreement with the predicted profiles.

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