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Old 01-31-2010, 10:29 AM
Alastor187 Alastor187 is offline
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Re: Automotive structural fatigue.

Quote:
Originally Posted by MagicRat View Post
Good points.

I have noticed my older cars creak, groan and pop much more in the cold. Some of this is the effect on adhesives, some I think is because the ride is stiffer, due to more rigid tires and shocks.

As for structural fatigue, this reminds me that most older Fox-body Mustangs I have encountered develop floor pan cracking behind the driver's seat. My old '79 V8 Mustang had massive cracking that I had to weld up. I noticed the metal was 'work-hardened', like dented and hammered body work, as Curtis says.
Even my '87 4 cyl Mustang had this same problem.

Other cracking examples.... second-gen Camaros and Firebirds would sometimes develop cracked roofs, especially the T-tops
Fair enough...then indeed metal fatigue is one cause.

One thing that would interesting is to see some of these cracks, in particular where they originated. For a complex geometry any kind of change in geometry (i.e. holes, corners, joints) are going to be areas of increased stress and therefore reduced fatigue life. So I would expect those kind of areas to be some of the first to start to fatigue.
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