Some embodiments provided rotor assemblies, comprising: a rotor core barrel comprising a wall extending, and at least two compression bridges each formed in the wall proximate one of the lateral ends and separated by a distance; an array of a plurality of magnets positioned on and spaced along the wall between the compression bridges and about a circumference of the rotor core barrel; and one or more pre-stress wraps wrapped over the plurality of magnets and about the rotor core barrel along at least a portion of a length of the rotor core barrel between the compression bridges, wherein the compression bridges enable radial compression deflection, induced by radial compression of the rotor core barrel by the one or more pre-stress wraps, of the wall of the rotor core barrel at the compression bridges relative to the wall of the rotor core barrel proximate the lateral ends.