Wood or metal the important thing IMO is that the doubler be thoroughly attached to the torn framing member over a large surface area.
I suggest to attach the doubler (angle iron if metal or a ~2x3 if wood) only to the perpendicular surface of the framing member so all the loads on the bolts and through holes are in shear, not tension, while the opener is pushing or pulling on the door.
Then attach the shoe of the opener bracket to the doubler using stouter hardware and larger washers than the original installation. So the inevitable push/pull forces delivered by the through-bolts are distributed over a large area on the doubler.
What you do NOT want is for any of the opener’s loads to be carried by the torn edges of the existing door framing member. Nor any metal within an inch or two of the torn edges. All that nearby metal is already weakened and will fail quickly if subjected to more bending stress.
My BIL & I installed an opener on my mum’s heavy wooden garage door…
IIRC, it had sensors to detect if there was an obstruction (eg person) when
closing the door but i don’t think there was a similar detector when opening.
Maybe that’s the reason the opener pulled the bracket off, so maybe a good thing
that the place where the opener is attached is weaker so as to act like a fuse
preventing damage to the main part of the door if it happens again.
I’d call out a garage door company for an eval. Something went catastrophically wrong. I’d want to be darned sure I knew what that something was before I put a band-aid solution in place.
Just to add … my concern about many of the suggestions so far is that they may be equivalent to blowing a fuse in your car, and then replacing it with a higher amperage fuse … as opposed to troubleshooting the underlying problem.
If there’s an issue with your tracks, your door, or your opener (system), then you found your failure point. Buttressing that failure point could simply relocate it to somewhere more critical … less safe … more expensive to fix … or any/all of the above.
I think the problem stems from a year ago when the door was getting caught on the door frame. But why it failed a year later and moreover while the door was going down is the puzzler.
If I could weld, I would weld a long metal bracket to the failure point to spread out the force of opening and closing.
Tracks are fine but could use their annual lubrication. And I checked the spring tension. No problems there. I think the opener is getting old so that probably should be replaced sooner rather than later. Maybe as part of this door fix.
Once the metal had started to tear in overload while your door was jamming you were on a trajectory to inevitable eventual failure. Each movement of the door, even after all your jamming problems were solved, would incrementally extend the tear that was already underway. And the more it tore, the weaker and more tear-prone it became. At some point the residual strength of the surviving metal couldn’t handle the forces of a normal door cycle and the tear finished tearing all the way.
It seems fine until it suddenly isn’t. But if you took a micro-detailed picture of the damaged area since the start, you’d have a slo-mo movie showing the process and its accelerating trajectory until suddenly “boom”; the last inch tears out all at once.
That sheet metal is far too thin to weld reliably. And doubly so if it’s aluminum. Better to bolt the doubler in place, but use plenty of bolts.
Your instinct to make it a lot bigger to spread the load is a good one. I’d probably use something about 12-15" long and as wide as will fit in there. Which looks to be 2-3".
Update.
It’s been a while but I finally had some people out for estimates and all came in about $200
BUT the last guy let it slip that the reinforcement is not something you build but rather an actual part and costs about $75 + labor so I did a little research
It costs $20-$30 depending on brand and with an 11mm socket I can install it in about 5 minutes.