A power conversion device has a buckled wave disk that has an axis and is radially compressed between a hub and a wave ring. The buckled wave disk is buckled in the radial direction to form circumferential waves which are displaced in the axial direction and extending around the buckled wave disk with lines formed of inflection points of the circumferential waves extending between the hub and wave ring. The wave ring is outwardly radially displaced at nodes corresponding to lines formed of inflection points of the circumferential waves. A wave propagation actuator cooperates with the buckled wave disk for driving a wave and the lines formed of inflection points of the circumferential waves around the buckled wave disk. An outer ring surrounds the wave ring, the outer ring being driven by or driving the wave ring at the nodes. A method of making a wave disk is provided.