It's impossible to know for certain how the thing became separated from the original structure.
I disagree. We have three distinctly different kinds of failure - lateral tearing, fracture (both across and with the grain of the metal), and fatigue from cycling - and they had to occur in that order for the piece to end up looking as it does.
I will agree that 'final cycling back and forth until it failed from fatigue,' brings up a picture of a Niki Islander scavenging metal from one of the many wrecks on Canton Island, or Funafuti Island, the C-47 wreck on Sydney Island, or the wrecks said to be on Baker Island, etc...
Perhaps to you, but not to me - perhaps because I have a better understanding of how mobile the laborers on Gardner Island were (or rather weren't). We've gone to great lengths and expense to locate, photograph, and digitize the
daily diaries kept on Gardner Island. If you take the time to read them you'll understand how absurd it is to think that "Niki Islanders" cruised around the Pacific scavenging wrecked airplanes.
"...[T]he wreck [of the C-47 on Sydney Island] became the chief source of aluminum for the islanders, who had learned on Canton Island to make women’s combs and other ornaments from this material. Eventually almost nothing remained of the aircraft."
The "islanders" referenced were the Sydney Islanders. None of the airplane debris found on Nikumaroro can be traced to the Sydney crash. There is one anecdote about the comb but even that is purely speculative. We do have several documented B-24 parts.
As a side note, the DC-3 repair manual calls for AD3 rivets- [or size 3/32"] to be used in wing tip skin repairs- "...replacing type and pattern of original rivets." The C-47 that crashed on Sydney Island- a military model of the DC-3- by chance, had it's wing tip repaired on Canton Island just days before the crash.
If C-47 wingtips were .032 sheet we'll have to see if the rivet pattern is anything like 2-2-V-1. What kind of accident would leave a wingtip looking like 2-2-V-1?
Your postings are increasingly following a well-known pattern. When critics are unable to offer valid challenges to hypotheses they start throwing around alternative explanations that ignore or dispute established parameters. That's trollism.