A method for manufacturing a rotor assembly for an electrical machine, the method comprising: manufacturing, using an additive manufacturing process that fuses together successive layers to form a unitary component, a first part of a rotor shaft; manufacturing, by the additive manufacturing process, a rotor core extending between a first end and a second end and having a core body and a core portion of the rotor shaft formed unitarily with the core body, the core portion of the rotor shaft extending between the first end and the second end of the rotor core, wherein the rotor core is manufactured as a solid core; and manufacturing, by the additive manufacturing process, a second part of the rotor shaft, wherein the second part of the rotor shaft is connected to the core portion of the rotor shaft at the second end of the rotor core and the first part of the rotor shaft is connected to the core portion of the rotor shaft at the first end of the rotor core; wherein the rotor core comprises a plurality of poles projecting radially from the core body; wherein each one of the plurality of poles comprises: a pole body extending circumferentially between a first wall and a second wall; and a pole shoe projecting radially outward from the pole body, and defining a peripheral surface; the rotor core is manufactured such that a plurality of cooling openings are defined by the pole body of one or more of the plurality of poles, wherein at least one of the plurality of cooling openings extends along the pole body and is positioned proximate the first wall of the pole body and at least one of the plurality of cooling openings extends along the pole body and is positioned proximate to the second wall of the pole body, and the method further comprises winding a rotor winding around each one of the plurality of pole bodies to form the rotor assembly. manufacturing, using an additive manufacturing process that fuses together successive layers to form a unitary component, a first part of a rotor shaft; manufacturing, by the additive manufacturing process, a rotor core extending between a first end and a second end and having a core body and a core portion of the rotor shaft formed unitarily with the core body, the core portion of the rotor shaft extending between the first end and the second end of the rotor core, wherein the rotor core is manufactured as a solid core; and manufacturing, by the additive manufacturing process, a second part of the rotor shaft, wherein the second part of the rotor shaft is connected to the core portion of the rotor shaft at the second end of the rotor core and the first part of the rotor shaft is connected to the core portion of the rotor shaft at the first end of the rotor core; wherein the rotor core comprises a plurality of poles projecting radially from the core body; wherein each one of the plurality of poles comprises: a pole body extending circumferentially between a first wall and a second wall; and a pole shoe projecting radially outward from the pole body, and defining a peripheral surface; the rotor core is manufactured such that a plurality of cooling openings are defined by the pole body of one or more of the plurality of poles, wherein at least one of the plurality of cooling openings extends along the pole body and is positioned proximate the first wall of the pole body and at least one of the plurality of cooling openings extends along the pole body and is positioned proximate to the second wall of the pole body, and the method further comprises winding a rotor winding around each one of the plurality of pole bodies to form the rotor assembly. a pole body extending circumferentially between a first wall and a second wall; and a pole shoe projecting radially outward from the pole body, and defining a peripheral surface; the rotor core is manufactured such that a plurality of cooling openings are defined by the pole body of one or more of the plurality of poles, wherein at least one of the plurality of cooling openings extends along the pole body and is positioned proximate the first wall of the pole body and at least one of the plurality of cooling openings extends along the pole body and is positioned proximate to the second wall of the pole body, and the method further comprises winding a rotor winding around each one of the plurality of pole bodies to form the rotor assembly.