Metal surfacing technical name

HAWK12HT

anyone know the name of surface on the left, there is a term for it I forgot. Applies to metal fabrication, basically that three point convergence area in mid cause fatigue. surface on right is the solution afaik. Thank you

FrankPolygon

The point of convergence that may increase the risk of fatigue would be a Stress Riser or Stress Concentration. Junctions are usually described by letters that have similar shapes: T, K, X, Y, etc. Intersection names can vary by location or trade. What the offset area is called will probably depend on whether this is square tubing or sheet metal and how the adjacent shapes are constructed. If none of these are helpful then more information about what's being replicated is needed.

HAWK12HT

@FrankPolygon nothing specific being replicated. Its just was related to metal works (I think) single metal sheet cant be formed into that shape on left due to the point in mid as it will rip n tear (fatigue) something to do with concave convex. The reason I researched into this was that in games or movies we can go crazy with shapes and that left part was a part of robot body (metal) which looked cool however since I have studied product design I had doubts that this shape will not work in real world so I researched into it and I was right but I lost the name of the term this shape (joint) falls into arghhh.  Thanks

FrankPolygon

If it's helpful: the intersection on the left is similar to a three member miter or mitered corner. The extra space on the intersection on the right is likely some kind of relief to allow forming tool access and reduce stress. Both have sharp corners that need a minimum radius to reduce stress concentration and be workable in a forming process.

With sheet metal forming, stress concentration is a big concern but complex sheet metal parts can be formed in smaller sections and welded, riveted or adhered together. Incremental forming and hydro forming can also be used to create complex shapes out of sheet metal parts that are welded together to make things like vehicle body panels, sub frames and fully boxed ladder frames, etc.

It would be difficult and expensive to make either of those shapes out of a single piece of formed sheet metal but there's a lot of different fabrication processes so I would be hesitant to say that the intersection on the left wouldn't work in the real world. Similar intersections are used to create roll cages and trailers from welded sections of square and round tubing, flat bar, beams, etc. These type of overlapped tubular joints also tend to have more strength than gaped tubular joints. Containers, shrouds and flat or angular body work can also be made using similar joins and multiple pieces of sheet metal.

Maybe there's some greater story context missing but the shape doesn't seem like it would be considered a likely candidate for a single sheet forming process when there are better alternatives. From a manufacturing standpoint it seems that a straightforward processes like using angle stock, flat bar, square tubes or sheets welded together would make more economic sense.

If the shape required a smooth cosmetic finish then the welds could be ground off and blended in before painting. The requirement that it be made out of a single piece of formed sheet metal feels too arbitrary. It would be interesting to see the concept art / model to get the broader story context of the whole object.

HAWK12HT

@FrankPolygon Thank you so much for more in detail breakdown, I agree car roll cages and bike assembly (tubes) do fall into shape on left.  Smooth welding options too 

Well not making anything for manufacturing its just my head is stuck in recalling the term I found when modelling this mech shown in pic, the red circle area to be specific. Two smaller purple circles show points that were connected (as in the whole intake face imagine it being a bit forward) while it looked ok and worked as in normal maps and modelling it just didnt feel right in terms of design, since its like a tank that particular area showed weakness so I moved the air intake area a bit back to add some logic. So thats when I found out the manufacturing term for this particular area. 

Second picture is from my practice session following Arrimus3d youtube, again the shape looks cool but not feasible imo. 

 Edit:



This is one of the solution I did quickly to make the shape ground to reality, I extended the upper half edges outward a bit so they blend gently with bottom half compared to the original shape. 
First version looks like its breakable kinda like sprue from plastic scale modelling kit, if you hold the sphere part and spin it will come off from the flat circle base (hope it make sense) however it will be super hard to sell this as part of hard surface metal design.

I even looked into hyberbolic shape stuff just to recall the damn name of this kind of surfacing. Should have written it back than....     

FrankPolygon

I see what you're saying. Assuming that mech is the same size or larger than a person then it's likely that it would be made out of multiple parts. Many of the shapes are still plausible if they were formed separately and welded together. Another design consideration (if the mech will face kinetic projectiles) is eliminating shot traps where angled surfaces transition into other surface features. Evaluation documents from WW2 and Cold War era tanks and tank design proposals often note shot traps and how they were resolved in later production models.

The red shapes look similar to the top of the shock towers that are formed as part of the inner fender wells on unibody vehicles. There's a drawing and coining process used to create these sort of shapes but the wall segments need to be tapered and have soft radii in the transition areas to avoid stress concentration and tearing.

Is the name of the shape / surface a single word or multiple words and is it related to or used in software and design processes or shop fabrication processes? Was the name mentioned in a tutorial, trade article or academic white paper? If the term was used in a specific trade was it machining, welding, sheet metal forming, product / manufacturing design, etc. ?

Trying to recall where and when you saw the name for that shape may help in remembering the name or how to get back to the source material. Any similar or related shape names may also be helpful.

HAWK12HT

@FrankPolygon well it was a simple google search somewhere along the lines of concave / convex intersection, shapes collapsing on themselves etc cant really recall. It was not related to any 3d software or art however it was from manufacturing / fabrication processes. Thanks to you I now know another new term I will look into "shot traps" haha 

Funny enough I know for sure I did a google search straight up and I got the answer, so it is a possibility I read it in product design manufacturing process book somewhere in college library and it stuck with me all those years but now out of nowhere I have this sudden urge to know what it was called arghhhh. Like if I will teach 3d artist to not make this shape in design how would I explain....that is bothering me a lot lol even though I am not teaching but you know when you discuss ideas etc you need to backup your claim. 

Again thanks a lot for helping me out...I still wish I can find the answer. The search continues  
 

HAWK12HT

@FrankPolygon hope you are doing well mate, today I found it out of the blue and it was not related to manufacturing at all 

NON-MANIFOLD is the term!!!! finally peace! 

FrankPolygon

@HAWK12HT Thanks for the update. Glad you were able to find the term and posted the conclusion here.