Systems and methods for intentionally breaking shafts of compromised electric machines with electro-thermal activation

An aircraft comprising

• an engine,
• an electric power system including a permanent magnet machine and an electric control unit coupled to the permanent magnet machine, the permanent magnet machine including a stator having a plurality of coils and a rotor having a plurality of permanent magnets and configured to rotate relative to the stator to move the plurality of permanent magnets relative to the plurality of coils of the stator,
• a shaft coupled to the rotor of the permanent magnet machine to transfer rotation from the engine to the permanent magnet machine to drive rotation of the rotor, the shaft including a first shaft end segment coupled with the engine and comprising electrically conductive metallic material, a second shaft end segment coupled with the permanent magnet machine and comprising the electrically conductive metallic material, a shaft body comprising electrically non-conductive material that extends between and interconnects the first shaft end segment and the second shaft end segment, and a fuse imbedded in the shaft body and configured to generate heat when an electric current is passed through the fuse, and
• a control system including a controller coupled to the electric control unit of the electric power system and configured to direct the electric control unit to introduce the electric current through the fuse to cause the fuse to heat the shaft body above a transition temperature of the electrically non-conductive material of the shaft body to selectively cause failure of the shaft in response to the controller receiving a signal indicative of a fault in the permanent magnet machine so that the rotor of the permanent magnet machine is mechanically decoupled from the engine thereby avoiding generation of undesired electrical energy and/or heat.