How about the SpaceX tank struts? These were presumably designed with the aid of a computer, and were not as strong as they were needed to be.
The news stories focused on testing, but testing is kind of the emergency fail safe of product construction. The fix involved a redesign, not more testing, so it seems safe to say the initial design was a failure.
It is also possible that the requirements were off.
I could read that as either evidence that the CAD computations were wrong, or evidence that something completely different happened. For example, someone might have taken a shortcut in manufacturing.
Most of the struts performed to spec, with a fraction of a percent failing under much less force than they should have. That sounds like a manufacturing problem, not a design problem.
The news stories focused on testing, but testing is kind of the emergency fail safe of product construction. The fix involved a redesign, not more testing, so it seems safe to say the initial design was a failure.
It is also possible that the requirements were off.