Hybrid powertrain input torque management

A method of controlling a powertrain having a hybrid transmission between an input member and an output member, wherein an on-board controller executes the method comprising:

• monitoring input torque at the input member;
• monitoring critical vehicle characteristics of the powertrain, wherein critical vehicle characteristics include:
• a transmission operating mode;
• and
• an input speed of the input member;
• operating the powertrain at the input torque;
• determining an average input torque from the monitored input torque;
• determining an oscillation torque from the difference between the monitored input torque and from the determined average input torque;
• comparing the determined oscillation torque to a fatigue threshold;
• identifying a first fatigue event, wherein fatigue events occur when the determined oscillation torque exceeds the fatigue threshold;
• identifying a first fatigue peak with the on-board controller during the first critical event, wherein fatigue peaks occur when the determined oscillation torque changes between positive slope and negative slope;
• identifying a first critical vehicle characteristic set (first CVC set) occurring substantially concurrently with the first peak;
• and
• recording the first CVC set and the first peak in a look-up table accessible to the on-board controller.