How to determine variable amplitude in a fatigue analysis
How to determine variable amplitude in a fatigue analysis
(OP)
I am in the process of setting up some mechanical fatigue test of a medical device. I’d like to load the device ___ times with a daily activity load, and then load it once with a high impact load, and then go back to ___ times of a daily activity load. I've seen engineers in other industries (auto, aero, etc) use variable amplitude fatigue loading cycles, but was looking for specific examples. If you have references/publications, I'd love to read them. Would be interested to know how adding bouts of high impact loads affect fatigue life of a product/part. Thanks for your help.





RE: How to determine variable amplitude in a fatigue analysis
RE: How to determine variable amplitude in a fatigue analysis
google "fatigue analysis" to see how to set up a load spectrum ... which is basically figuring out a typical load magnitude (a max and a min if you need it, most often min = 0 is good enough) and then how often this happens.
another day in paradise, or is paradise one day closer ?
RE: How to determine variable amplitude in a fatigue analysis
RE: How to determine variable amplitude in a fatigue analysis
RE: How to determine variable amplitude in a fatigue analysis
To help validate your fatigue life analysis based on different load levels and number of times loaded, I would read up on Palmgren-Miner's rule.
http://aerospacengineering.net/?p=166
Again, meaningless and a waste of time and money if analysis work has not been preformed.
RE: How to determine variable amplitude in a fatigue analysis
RE: How to determine variable amplitude in a fatigue analysis
RE: How to determine variable amplitude in a fatigue analysis
You can do more testing if you want but it will not help your sales. Industry knows what an ISO rating of 275lbs means and what testing it has to meet. Additional unique testing will mean nothing to anyone but you and your company.
Unless you get brought to court and then you will lose no matter what. Juries always favor the handicapped, insurance companies will settle out of court and your company will end up paying.
RE: How to determine variable amplitude in a fatigue analysis
RE: How to determine variable amplitude in a fatigue analysis
SAE Fatigue Design Handbook
http://books.sae.org/ae-22/
Fatigue Testing and Analysis, 1st Edition
Theory and Practice
http://store.elsevier.com/Fatigue-Testing-and-Anal...
Fatigue of Structures and Materials
http://www.springer.com/us/book/9781402068072