The present teachings generally include a composite rotor assembly comprising a shaft and a rotor body mounted to the shaft. The rotor body can include a core structure including a cured polymeric material wholly or partly defining plurality of lobes joined by adjacent root portions. The rotor body can also include a support structure continuously extending the length of the core structure to provide additional structural integrity to the rotor body. The support structure can be wholly or partially embedded within the core structure and can also be wrapped around the exterior of the core structure. In one example, the core structure includes an epoxy resin and the support structure includes a carbon fiber material.