My Master's thesis project works with a system that mechanically prevents a DC motor from stalling and effectively thresholds the amount of current the motor draws and removes large current spikes from sudden loads. It seems intuitive to me that removing these spikes will extend the lifetime of the components in the system (motor, motor controller, battery, etc.) but I need some sort of reference as to why this should be true; ideally some type of study or journal article that I can reference in my thesis. I am also open to personal explanations. Thank you!
Look into "thermal cycle". Presumably any current spike would result in additional (albeit transient) power loss in the motor. Inside the motor there will likely be junctions (solder junctions ?) in the winding. The solder junction would be slightly higher resistance, thus slightly higher loss than the surrounding wiring. This would result in a temperature rise at the solder junction (again probably small). However, a rise in temperature and subsequent drop in temperature is known as a "thermal cycle". I have dealt with thermal cycling in substrate bonded semi-conductors where thermal cycling reduces the lifetime of the semiconductor by eventually tearing away of the bond.
It may take several million extreme thermal cycles to disrupt or destroy equipment, but then in an extreme environment, it might do well to at least consider thermal cycles. EDIT : add link : http://nepp.nasa.gov/docuploads/99810235-C28A-4A8D-BD52223A33EF7CDF/ASME-Hawaii993-lockeed.pdf