Translation of "Stress cycle" in German

Thanks to its excellent mechanical stability, Glastherm® can withstand and long endure the high dynamic stress in short-cycle presses.

For this purpose, the pacemaker is operated temporarily in each case in the demand mode, preferably upon completion of the stress cycle when the patient's heart frequency is decreasing, so as to follow the patient's decreasing heart frequency so closely that stimulation signals are supplied positively at regular intervals in a frequency pattern during the decreasing spontaneous heart activity so as to temporarily stimulate the patient's heart with a previously encountered higher (spontaneous) frequency.

For automatic adaptation corresponding to a "self-teaching process" which is also possible without running through a stress cycle under supervision of a physician on the basis of the changes in stress occurring during normal activity, the control range for stimulated frequencies would be adapted to that control range which would be covered if spontaneous actions were to occur.

With spring steels produced with the observance of the aforementioned production parameters, it is possible to achieve excellent spring properties even at very high stress cycle numbers.

Instead, it has surprisingly been shown that steel composed according to the invention, having a fine-lamellar pearlite structure (sorbite), specifically for cold rolling, fulfills the requirements with regard to an increase in strength as well as an improvement in the achievable expansions and thus of the deformability of the material, as well as the usage properties with regard to the stress cycle numbers of spring components produced from it, and the required surface grades, in exemplary manner.

In the period between the points in time t 1 and t 7, the steam turbine thus passes through a complete stress cycle with heating up and cooling down of the selected part.

In this case a complete stress cycle of the part is referred to as the load cycle, in which, starting from an initial state, the curve passes through a maximum in the stress, occurring for example through a maximum mechanical tension, and subsequently, after a zero crossing, a minimum in the stress, occurring for example through a maximum mechanical compression force.

The end point of this stress cycle referred to as the load cycle is reached when the part, after alternately undergoing tension and compression, has again reached its original state.

The overall load cycle occurring in such a stress cycle is in this case usually the overall range of variation of the stress passed through, i.e. the difference between the stress values when minimum compression force and maximum tension force are present.

In this case the invention uses as its starting point the idea that even a method suitable for a comparatively timely prediction of the current fatigue state of a part should be designed to be independent of possible comparatively long time intervals in the ending of a stress cycle.

This can be achieved by also taking into account knowledge about the current load cycle which already exists but has not yet been completed in determining the approximate value of the parameter characteristic of the fatigue state, even if a comparatively high inaccuracy may possibly have to be taken into account for this parameter because of the only incomplete data available of the current stress cycle.

In order to achieve this, measured values actually already present should also be taken into account to the greatest possible extent in the stress cycle currently being run but not yet completed, in which case, to allow further processing of the not yet available characteristic stress values for the phases not yet run of the partly completed load cycle, a suitable fixed value as a type of placeholder is predetermined as a substitute value.

As a result of the microscopic rearrangement processes produced by the stresses shown, when a part passes through this type of stress cycle—also called a load cycle—a weakening of the part—also referred to as fatigue or exhaustion of the material—occurs, resulting in reduced mechanical ability to withstand loads and such like.

An estimated value for the additional fatigue can be assigned to this based on previous experience, if necessary using data stored in a database, which the part has experienced after passing through the entire stress cycle represented by the stress curve 2 .

Precisely in the example of the stressing of a component of a steam turbine shown, the overall stress cycle executed can however extend over a significant period of time, for example over months or years.

In order in this case not to have to depend for the determination of the approximate parameter characteristic the current fatigue state of the part on the complete sequence of the current stress cycle and to be able to make a high quality prognosis statement in an especially timely manner, in the determination of the approximate parameter characteristic for the fatigue state of the part as a result of the time-varying characteristic value for the load, in addition to the if necessary already completed load cycles, there is provision to also take account of a partly completed load cycle, in which case temporary stress values for phases of the partly completed load cycle not yet executed are taken into account, with a zero value as predetermined fixed value.