Vibration fatigue of a vibration fatigue analysis is the modal analysis, that exposes the natural modes and frequencies of the vibrating structure and enables accurate prediction of the local stress responses for the given excitation. Only then, when the stress responses are known, can vibration fatigue be successfully characterized. The more classical approach of fatigue evaluation consists of cycle counting, using the rainflow algorithm and summation by means of the Palmgren-Miner linear damage hypothesis, that appropriately sums the damages of respective cycles. When the time history is not known, because the load is random ("e.g." a car on a rough road or
Pound per hour Pound per hour Pound per hour is a mass flow unit. It is abbreviated as PPH or more conventionally as lb/h. Fuel flow for engines is usually expressed using this unit. It is particularly useful when dealing with gases or liquids, as volume flow varies more with temperature and pressure. In the US utility industry, steam and water flows throughout turbine cycles are typically expressed in PPH, while in Europe these mass flows are usually expressed in metric tonnes per hour: Minimum fuel intake on a jumbo jet can be as low as 150 lb/h when idling; however, this is