Reduction of testing time in structural durability proof.

A reduction of testing time can be achieved by an increase of testing frequency and/or increase of the load level. However, effects resulting from a subpressing of plasticity or of exposure time to corrosive environment, which may render a better fatigue life than reality, or a not tolerable temperature increase or relieve of beneficial residual stresses, which may decrease the fatigue life, must be avoided. The fatigue behaviour determined under variable amplitude loading cannot be assessed generally from the behaviour under constant amplitude loading. An omission of probably non damaging low amplitudes with a high occurrence can contribute to a shortening of testing time. However, a damage equivalent compensation of omitted amplitudes by increasing of higher loads with lower occurrence is recommended. In case of a simulation with several actuators if a multichannel omission is carried out, then the correlation between the loads of the particular channels must be kept. Testing time reduction bases on several compromises. Especially, the experimental proof of safety components requires the consideration of all aspects according to the present state of the art and must include experiences from the field.