TABLE OF CONTENTS The principle of this design check in Annex B of EN 13445-3 is very general: The design value of the accumulated fatigue damage index D d for cyclic fatigue, obtained for all the (cyclic) design functions of pressure/temperature and variable actions, shall not exceed 1 (EN 13445-3, Annex B).
This requirement is given meaning by the corresponding application rule, which refers to clause 18, the fatigue clause in the DBF section of EN 13445-3: Fulfillment of the requirements given in clause 18 suffices as a check against fatigue failure (EN 13445-3, Annex B).
Therefore, the cyclic fatigue requirements given in this clause 18 are dealt with in the following, with the incorporation of the requirements for the consideration of cladding given in the fatigue sub-clause of Annex B of EN 13445-3. Of course, emphasis is on the usage as a design check within the DBA approach. Clause 18 of EN 13445-3 not being incorporated in Annex B, the annex containing all the other requirements for the Direct Route in Design by Analysis, and having seen so many misuses, it seems to be necessary to repeat the warning with regard to design checks: Clause 18 is, in its intention and planned usage, a design check it is not meant to give rules for a simulation of the fatigue behaviour of real structural parts, it is not meant to give an approximation of the fatigue behaviour, nor has it been developed for...
