Fatigue Testing
Fatigue Testing
(OP)
Hi I'm after some advice
If I have a component that must flex 50 times through its life (2 months), I have an automated test fixture that will flext the component and check for a failure, (true return position).
If I wanted to prove that the component woudl not fail in normal operation say to 1:10,000 at 95%, I belive I'd have to test 30,000 parts to 50 flex's.
Now I only have 10 parts available, although completly representative of the final part.
So can I test each of the 10 parts to 3,000 actuations, and deduce the same fact. i.e
Is it true or fair to say, To test to a failure rate 1:10,000 @ 95%, I could either :-
Test 30,000 components, once each Or
Test 10,000 components, 3 times each Or
Test 1,000 components, 30 times each Or
Test 100 components, 300 times each Or
Test 10 components, 3,000 times each Or
Test 1 component, 30,000 times each ?
Some help would be great.
Thanks
Arron
If I have a component that must flex 50 times through its life (2 months), I have an automated test fixture that will flext the component and check for a failure, (true return position).
If I wanted to prove that the component woudl not fail in normal operation say to 1:10,000 at 95%, I belive I'd have to test 30,000 parts to 50 flex's.
Now I only have 10 parts available, although completly representative of the final part.
So can I test each of the 10 parts to 3,000 actuations, and deduce the same fact. i.e
Is it true or fair to say, To test to a failure rate 1:10,000 @ 95%, I could either :-
Test 30,000 components, once each Or
Test 10,000 components, 3 times each Or
Test 1,000 components, 30 times each Or
Test 100 components, 300 times each Or
Test 10 components, 3,000 times each Or
Test 1 component, 30,000 times each ?
Some help would be great.
Thanks
Arron





RE: Fatigue Testing
Moreover, since there are a number of long-term and thermal-related issues with fatigue failures that going past 500 actuationson a single unit wouldn't make much sense. Some materials tend to work-harden, so exercising beyond a certain point fundamentally changes the parameters of the material itself, thereby nullifying any potential conclusions. Likewise, mechanical working of a material that can fatigue induces heat, which can accelerate or otherwise alter material behavior as well.
On the other hand, if all pieces can handle 3,000 actuations, then there isn't a problem beyond whether the pieces you have really encompass ALL possible process and material variations.
TTFN
Eng-Tips Policies FAQ731-376
RE: Fatigue Testing
What is the material? If metal, what is the loading vs. yield strength?
ISZ
RE: Fatigue Testing
RE: Fatigue Testing
Use some Weibull software, it takes away the headaches.
Bill