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REXS Specification

Woehler S-N curves

Woehler S-N curves are used in the fatigue strength calculations of various machine elements. Woehler S-N curves apply permissible stresses across load cycles.


A Woehler S-N curve can be assigned to the following components via a reference relation:

  • Cylindrical gears (cylindrical_gear, ring_gear)

  • Bevel gears (bevel_gear)

  • Shafts (shaft)

Multiple S-N curves can be assigned to a single component; e.g. for the root and flank load capacities. An attribute on the S-N curve is used to specify the calculation for which it can be used.


Required relations

XML syntax


<relation id="32" type="reference">
	<ref id="11" role="origin" hint="shaft"/>
	<ref id="14" role="referenced" hint="sn_curve"/>


<relation id="32" type="reference">
	<ref id="22" role="origin" hint="cylindrical_gear"/>
	<ref id="16" role="referenced" hint="sn_curve"/>