Use of fatigue life data S-N curves

- April 9, 2019 at 12:11 am
  
  PhiZi
  Subscriber
  
  Dear community,
  
  I am working currently at my Bachelor Thesis and have a question regarding the use of material data input (specifically the S-N curve data).
  
  I am using mechanical structural and the fatigue tool to determine the life time to failure. The used system is ANSYS Workbench 19.1. As input material data, the standard aluminum alloy from ANSYS database is used.
  
  The geometry is a simple cross section of a thick wall pipe. Analysis study in 2-D. The load is set as a constant pressure inside of the pipe with a magnitude of 90 MPa. This should lead to finite life time. The hook stess is still underneath the yield strength of the material which ensures a linear strain behavior. The support is realized by weak spring method. The actual loading case purely zero-based, r=0. The S-N curve interpolation method is set to log-log.
  
  Even if the load case is explicitly defined (r=0), I could realize a mixed use of all provided S-N curve ratios. The fatigue life time changes if single curve ratios will be removed. No result could be validated by analytical approach which is proved by my Professor for fatigue and fracture. How is the application of the S-N curves in ANSYS defined? I cannot find any concrete information about this.
  
  I would be glad about any helpful information.
  
  Thanks!
  
  Philipp
- April 9, 2019 at 11:04 am
  
  sathya
  Subscriber
  
  Hi Go through this link and get back.
  
  https://web.njit.edu/~sengupta/met%20301/cyclic_loading%20indefinite.pdf
- April 9, 2019 at 11:44 am
  
  peteroznewman
  Subscriber
  
  That link doesn't work. Can you put the pdf file in a zip file and Attach it to your post?