I wanted to know if it was possible to estimate fatigue life of a pressure vessel at low stress if you know its failure conditions at a higher pressure. As it is possible for me to test the vessel at higher pressure for lower number of cycles but testing for larger number of cycles will be too much time consuming.
For example if a vessel fails after 20 cycles at 700 MPa, and fails after 35 cycles at 650 MPa, is it possible to estimate the number of cycles it will survive at 400 MPa.
In general, fatigue life is determined from SN curves of the material.
Also, there is the Solderberg method