NYC777
Topic Author
Posts: 5083
Joined: Wed Jun 09, 2004 3:00 am

Static Testing Vs Fatigue Testing Question

Wed Nov 21, 2007 4:48 pm

Hi all,
I was wondering what was the difference between static test air frames and fatigues test air frames.

What are the test that are involved, how long does it take and shat are they trying to accomplish?

Thanks.
That which does not kill me makes me stronger.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Static Testing Vs Fatigue Testing Question

Thu Nov 22, 2007 3:32 am



Quoting NYC777 (Thread starter):
I was wondering what was the difference between static test air frames and fatigues test air frames.

What are the test that are involved, how long does it take and shat are they trying to accomplish?

The frames themselves are basically the same, although I would assume they're instrumented differently.

The static frame will be put in a great big jig and subjected one-time tests to 150% of limit loads. Limit loads are the maximum the aircraft is expected to see in it's life. The static testing will be on the order of months.

The fatigue frame will go in a similar, though not quite as beefy, jig and subjected to thousands and thousands of simulated flight cycles. So the loading won't be as high as the static test frame, but they'll do it over and over and over. They need to have (I think) 50% of the design life of the aircraft on the fatigue test frame before the aircraft enters service. Eventually, they'll test it up to (at least) twice the design life. They'll stop periodically to do inspections, find the weak points, etc. That test will probably go for years.

Tom.
 
NYC777
Topic Author
Posts: 5083
Joined: Wed Jun 09, 2004 3:00 am

RE: Static Testing Vs Fatigue Testing Question

Thu Nov 22, 2007 8:12 pm



Quoting Tdscanuck (Reply 1):
The frames themselves are basically the same, although I would assume they're instrumented differently.

The static frame will be put in a great big jig and subjected one-time tests to 150% of limit loads. Limit loads are the maximum the aircraft is expected to see in it's life. The static testing will be on the order of months.

The fatigue frame will go in a similar, though not quite as beefy, jig and subjected to thousands and thousands of simulated flight cycles. So the loading won't be as high as the static test frame, but they'll do it over and over and over. They need to have (I think) 50% of the design life of the aircraft on the fatigue test frame before the aircraft enters service. Eventually, they'll test it up to (at least) twice the design life. They'll stop periodically to do inspections, find the weak points, etc. That test will probably go for years.

Tom.

Thanks! I was told that fatigue testing on the 787 will take place outside. Has anyone ever heard of that heppening?
That which does not kill me makes me stronger.
 
xtoler
Posts: 277
Joined: Tue Sep 18, 2007 8:10 am

RE: Static Testing Vs Fatigue Testing Question

Thu Nov 22, 2007 8:34 pm

Stupid question for you, but are you asking outside of the hangar or outside of Boeing? Don't hold me to this, as I'm no engineer, but some tests are done outside of a hangar. Especially when it comes to weather. I'm pretty sure some tests actually require flight. But as far as predicting fatigue without actually testing an airframe to the "elements", I'm not sure how that would be done. A lot can be simulated, but I think some of it has to be done the "ol' fashioned" way, regardless of how the aircraft was designed.
EMB145 F/A, F/E, J41 F/A, F/E, because my wife clipped my wings, armchair captain
 
RebelDJ
Posts: 72
Joined: Thu May 03, 2007 3:27 pm

RE: Static Testing Vs Fatigue Testing Question

Thu Nov 22, 2007 9:36 pm

Don't get confused between fatigue testing, which was the OP's question, and all the other testing to which a new aircraft is subjected. I would expect that due to instrumentation factors alone, fatigue tests would need to be done inside. Reply 1 is correct about the difference between the static and fatigue test frames.
 
NYC777
Topic Author
Posts: 5083
Joined: Wed Jun 09, 2004 3:00 am

RE: Static Testing Vs Fatigue Testing Question

Thu Nov 22, 2007 10:08 pm



Quoting Xtoler (Reply 3):
Stupid question for you, but are you asking outside of the hangar or outside of Boeing? Don't hold me to this, as I'm no engineer, but some tests are done outside of a hangar. Especially when it comes to weather. I'm pretty sure some tests actually require flight. But as far as predicting fatigue without actually testing an airframe to the "elements", I'm not sure how that would be done. A lot can be simulated, but I think some of it has to be done the "ol' fashioned" way, regardless of how the aircraft was designed.

Outside meaning outdoors.
That which does not kill me makes me stronger.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Static Testing Vs Fatigue Testing Question

Thu Nov 22, 2007 10:43 pm



Quoting NYC777 (Reply 2):
I was told that fatigue testing on the 787 will take place outside. Has anyone ever heard of that heppening?

I'm pretty sure it's inside. Not that I have any actual information on that front, but the fatigue test tooling isn't exactly something subtle. If they were going do it outside somebody around Everett would have noticed a monster setup like that being constructed.

Tom.

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