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
Kinetic theory of gases can calculate the number of atomic or molecular collisions with a wall of a container per unit area per unit time. Assuming an ideal gas, a derivation results in an equation for total number of collisions per unit time per area: This quantity is also known as the "impingement rate" in vacuum physics. From the kinetic energy formula it can be shown that where "v" is in m/s, "T" is in kelvins, and "m" is the mass of one molecule of gas. The most probable (or mode) speed formula_26 is 81.6% of the rms speed formula_27, and the mean (arithmetic