You property of the materials that you seem to be keyed in on is modulus of elasticity. You can get around this by increasing sectional thickness so the material will not flex as much and there fore not fatigue Like I said, if the frame is properly engineered out of its respective material, then your original statment is still wrong.
As for your offer, I am interested in seeing which engineering books that you are misunderstanding. Just because you design and build things, does not mean that you know what you are doing.
Thank you, drive through. :laugh: