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Re: How strong is this kind of weld?
I believe you're right about that Kelvin, cutting the top and leaving the bottom flange bended would be the better choice as I suspect the greatest force on the wings would likely be the extreme lift felt when exiting a dive. Excellent point and duly noted!
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Re: How strong is this kind of weld?
Aluminum is used often on scale hobby aircraft I believe, but indeed not on the common hand-thrown planes.
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Re: How strong is this kind of weld?
Originally Posted by
Jack732
Brett, that's a very good point you made. I hadn't considered it. The only downside to having the gusset extend to include the king post (that I can see) is that it won't be between the flanges of the I-beams which would give added support. Do you think that that loss in strength would be somewhat negligible?
Thanks,
Jack
All you need to do it cut back the bottom flange by the thicknes of the gusset and ony for half the width of the gusset .
I also agree with Boostinjdm that what Im describing is for something large .
Last edited by Brett; 04-06-2021 at 11:27 PM.
A good guess is better than a bad measurement
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Re: How strong is this kind of weld?
I've perused all of the posts in this thread, and haven't noticed a mention of the dimensions of this project. Might be of value, so we can know how to best advise.
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Re: How strong is this kind of weld?
Weldordie, I do not have exact dimensions as of yet. Good suggestion though.
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Re: How strong is this kind of weld?
That's a good work around, I'll keep it in mind! Thanks Brett!
Jack
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Re: How strong is this kind of weld?
Originally Posted by
Willie B
I make benches from old extension ladders. They involve a joint like yours. I put a flat piece of 1/4" plate at the intersection. I then fillet weld all around the ladder rails. Never had a failure. These ladder sections are typically 6" from foot to foot, perhaps 4' flat plywood as the top. Maybe 18" tall, never more than 2' tall.
What this cat sez...
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Re: How strong is this kind of weld?
Originally Posted by
Jack732
Weldordie, I do not have exact dimensions as of yet. Good suggestion though.
Exact dimensions, probably, not needed. Are we to consider feet or inches? Approximate either way will help.
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Re: How strong is this kind of weld?
Originally Posted by
Jack732
Hello, I was needing to join two aluminum i-beams at about a 167 deg angle angle between them (joining them flat would result in a 180 deg angle between them).
They would need to be cut at a slant to achieve this small angle. Once joined the beams will be loaded normally with vertical loadings.
My question is, would this angle weld significantly reduce the strength of the overall beam? And if so, would it then be better to bolt the angle instead of welding it?
see the attached picture for reference, thanks
Jack
If you were using it with the legs up and applying pressure upwards to the ends and pressure down to the V-joint you could just cut out a wedge from the I-beam and leave the one flange intact and then just weld up the cutout wedge after you bend it. I would anneal the flange before I bent it.
But if you are using it like a gable roof then you need supports either collar ties or ceiling joists the latter being stronger. But remember in a fire aluminum melts in seconds to a minute after a fire starts.
Sincerely,
William McCormick
If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.
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Re: How strong is this kind of weld?
Originally Posted by
Jack732
Hello, I was needing to join two aluminum i-beams at about a 167 deg angle angle between them (joining them flat would result in a 180 deg angle between them).
They would need to be cut at a slant to achieve this small angle. Once joined the beams will be loaded normally with vertical loadings.
My question is, would this angle weld significantly reduce the strength of the overall beam? And if so, would it then be better to bolt the angle instead of welding it?
see the attached picture for reference, thanks
Jack
With the angle being so low, and not knowing how high a beam it is I think the plates might be futile. Also, stainless steel bolts will oval holes and cut through aluminum if push comes to shove. But you would need to tell us about the span and the height of the beam and the load you plan. Also is it a stand-alone device or is it part of a bigger structure? If it is standalone, it may just twist if not held in position, plates or no plates. But collar ties and chords to connect the two ends are superior to all. It creates an unmovable triangle.
Sincerely,
William McCormick
If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.
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Re: How strong is this kind of weld?
Originally Posted by
Jack732
This is actually a conceptual idea for the main spar of a flying wing aircraft drone. The reason the angle is needed is due to necessary anhedral in the wing.
I'm not an aeronautical engineer, but I did say in a Holiday Inn Express last night.
Anhedral? If you are using the term correctly - why in the world do you want reversed dihedral?
Joking aside, I was really big in RC fixed wing flying some years back. It is still one of those hobbies in the back of my mind I want to get more in to, but there is only so much time and there are so many other things in my world to think about and worry about.
What scares me about the design of the "anhedral" (if you are using the term properly) design is you will have an inherently unstable wing that will be a nightmare to control.
The whole premise of a dihedral angle in a wing (positive angle up, not downward as with anhedral) is that the lift in the wing causes lateral opposing force to stabilize the wing in flight. Its like the difference between towing a trailer going forward and backing up a trailer. Towing the trailer being akin to the dihedral angle and backing up a trailer being akin to the anhedral angle. The trailer inherently wants to pull straight behind, but will always try to achieve that (being straight behind) when you are pushing it in front as when you are backing = you have to constantly adjust to keep the point you are pushing from where it needs to be to get the trailer to go where you want it to be.
That aside, I agree with all the comments about reinforcing the spar beam in which side is in tension.
Keep in mind, the rest of the structure of the wing will give you the strength to resist against torsion in the beam. When you add your ribs in there and the rest of the wing structure that will compensate for the deficiencies in the beam alone to handle all the forces. So keep the assembly as a whole in mind - you don't want to over-engineer the beam and make it heavier than it needs to be when you have the other components already there in other places.
Last edited by FlyFishn; 04-10-2021 at 02:23 PM.
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Re: How strong is this kind of weld?
Hello Weldordie, I have all the information I need for a while. I'm closing this topic down temporarily. Thanks for all your help!
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Re: How strong is this kind of weld?
William,
Some very important points you made, I will especially remember your tip "...in a fire aluminum melts in seconds to a minute after a fire starts"
Also, the part you mentioned about steel bolts cutting through aluminum is also something I hadn't considered, very important.
It is a standalone device.
I am temporarily closing this thread due to need for specifics. I will no longer respond for a while. Thanks for your advice, it was very much appreciated!
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Re: How strong is this kind of weld?
FlyFishn,
Excellent points of interest you pointed out, indeed a flying wing with only anhedral would be nightmarish to control, even with a stability algorithm to aid. I was intending a wing that incorporated anhedral as well as dihedral. More dihedral than anhedral to cancel out the negative effects of the anhedral.
"Keep in mind, the rest of the structure of the wing will give you the strength to resist against torsion in the beam. When you add your ribs in there and the rest of the wing structure that will compensate for the deficiencies in the beam alone to handle all the forces. So keep the assembly as a whole in mind - you don't want to over-engineer the beam and make it heavier than it needs to be when you have the other components already there in other places."
Very powerful idea there, don't want to overcompensate and make it unnecessarily heavy. I will do my best engineering-wise to make it an optimal structure.
I am temporarily closing down this thread as I need more specifics and experience, I will no longer reply for a while, thank you for your input!!
Jack
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Re: How strong is this kind of weld?
**********************ATTENTION ALL********************
I am temporarily closing down this thread, please do not reply, I need more specifics and experience to be able to use any more help from this welding community. Thanks to all of you for your input, I feel I know so-so much more than before and I am determined to put together everything I have learned here into a real prototype design; in other words it's time to build and test!
Have a good one,
Jack
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Re: How strong is this kind of weld?
I am an engineer. I would suggest you find an independent engineer who runs SolidWorks. In most cities you can find them in the Buy and Sell under services, or online. To load this design, loads, and material into the software is fast and easy for an experienced user. You will get an exact welding procedure and any bracing required without guessing. A key reason for doing this is you won't overbuild. The calculations will give you what you need at minimum weight. Anther issue, if this is a drone, is vibration. A wood screw that will hold a hundred pounds for a hundred years in a barn wall won't hold ten ounces for ten minutes in a model airplane. The more you can tell the Solidworks operator about your loads the better will be your answer. Cool project. Good luck!
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