Endurance diagram

For the design of components that do not contain any defects and that are subjected to both alternating and mean stresses, a Soderberg diagram is normally used in a ‘safe life’ approach. However, structures may contain defects or cracks where a Soderberg diagram will not be sufficient. In this paper the development of an endurance diagram is presented for components that may contain crack-like defects left in the structure during the fabrication process. This diagram is based on the threshold stress intensity factor in fatigue crack growth, ΔK_th, and the critical stress intensity factor, K_c.