U channel and squire tube which one is strong



As a lab manager tasked with turning Ph.D's paper concepts into working hardware I noticed a divide between those who were really good with higher math and those who could visualize the workings of a machine or circuit. I can look at a truss and see which elements are in tension or compression but one of my physics teachers couldn't, he had to look for the sign of the force vectors, even for a simple triangular street sign support. OTOH I ran into a brick wall trying to understand Laplace Transforms and the s plane in college, where math was taught as an art form. Fortunately a chemist doesn't need it. Later I took electrical engineering classes in night school, taught by working engineers who used math to solve real-world problems, and their explanations of applying complex number theory to AC and RF circuit problems were MUCH easier to follow. This time instead of nearly flunking I aced Differential Equations and AC Circuit Analysis. Finally I could read the display on a vector network analyzer and know what to change to improve the circuit. In FEA terms that's like finding an unexpected stress riser.
Simulation is easier in electronics because measurements are less intrusive and the failures aren't destructive. It was pretty good at describing something that had already been done before, not so good at predicting into unfamiliar territory. For that we had to build, test, and adjust the sim and hardware models iteratively.
Here's a classic example of a failure caused by a mathematical model that was too difficult to implement: https://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse
The original design of the tie rods required the threads to support only one level, the rods' solid cores bore the weight of the walkways below. The redesign left the top level's threads and nuts additionally supporting the lower level.
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Hi Jim I read with interest. You are describing a like situation, as I understand it. You are seeing the same "mismatch". Thanks for taking me into your area of expertise in explaining.
Trusses and stresses - as I learned about vectors, wishing to design a bridge in the form of a truss, I realised I could look up at Victorian railway station roof supports and see which were in tension and which were in compression (here in the UK). Those in pure tension could be and often are flat plates, while those in compression are channel sections.
Best wishes, Rich S
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On 1/26/2020 6:22 AM, Richard Smith wrote:

You think in 3 dimensions ... most people just can't see what you see . I also have that ability , which is why I was so good at building "special projects" in the cabinet shop . I'm betting you can look at a drawing and visualize the finished product in your mind before the first piece of material is cut ...
--
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Hi Terry
Being "confronted" with this was a major juncture in my life.
That I can see things which few others will ever see in all their lives / careers.
That happened when I was in my mid-20's and was feeling very confused.
What this friend said was transformational - inverted the perception. That what I was seeing the real, and they were lost in a convenient substitute for reality.
I gained great self-confidence to go forth to the next step(s).
I got so successful pursuing science and technology that I attracted resentment from others who were actually very bright themselves, and wrecked-up unable to defend against so many causes attacking simultaneously.
But life as a welder, with occasional engineering jobs, is not bad... :-)
This about seeing things in simulataneous multidimensional dynamic interactions, interacting and intersecting to produce "contours" and "envelopes" of usable / interesting conditions. Rather than a narrative sequence of zero-dimension / single-point "rules" / assertions - rather like a "necklace" assembly of hard immutable points.
This is what many of "us" share (?)
In shop-floor "leadership" jobs (when I can get them in this "service-economy" country), I have to start with little things, so the people who have been doing the jobs a long time can see "I have something". Then build up to bigger refinements spanning across various processes. Delivering each time and becoming valued (given in manufacturing, most shop-floor workers know their job and reasonable way-of-life dependss on customers keeping on wanting what the company makes - more than what many management bother with).
Best was working in Turkey on the 3rd Bosphorus Bridge project - representing Hyundai (lead contractor). They expressed that I made it possible to complete the bridge, sorting out the steel (bridge-deck and tower + cable-anchor fitments) parts of the project. No job back in UK though - straight back to meeting this impenetrable wall of "non-discriminatory equal-opportunities" recruitment where administrative grades have seized control of interview / recruitment processes...
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My problem was reducing the multidimensional dynamic to a linear "necklace" in order to write up the results afterwards. I started posting here as practice. It's challenging to adequately describe some things without sketches.
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https://interestingengineering.com/3rd-bosphorus-bridge-worlds-widest
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Which could be translated as Oxford.
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.

The company where I apprenticed as a machine designer in the 1970's built custom automotive production test equipment weighing up to 5000 Lbs mostly out of relay racks they fabricated themselves from 12 gauge (2.6mm) sheet steel. Their machinery was a Niagara press brake and a Strippit punch press, and an old Polish welder whose TIG beads were as smooth as his disposition was rough. They consistently achieved a tolerance of 1/32" on the panel openings, so I could make my control panels 19.00" or 24.00" wide without any custom fitting for width or the squareness of the upper and lower corners.
We tapped the panel mounting holes #10-32 (~5mm) with a portable drill freehand. I retired taps after ~1000 holes, and never broke one. Back then the tapping fluid had carbon tetrachloride in it and worked very well.
Naturally any large motors or refrigeration compressors were on structural steel bases, but if the contents were all electrical the row of bolted-together racks could be 20' long and still very rigid. One such 5000# machine fell off a forklift during the customer's morning break and landed face-down on the electrical control panels. The frame was still in fine condition and was repainted and reused. I salvaged a bucket of Variacs that had been broken in several different ways and could be mixed and matched into nearly half as many usable ones for my home projects.
5000 Lbs was the most we could manhandle out onto the flatbed truck with pipe rollers and Johnson bars, due to lack of space to stand at the front of the loaded truck bed. The overhead gantry hoist didn't go out the loading dock. https://www.pbs.org/wgbh/nova/pyramid/geometry/blocks.html
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Interesting. Competition - reason you get regions where many do the activity - all have raised their game and people come from afar to "shop" there and get good stuff.
We mainly have 6013 (rutile), minority of 7018, and everyone things no-one uses 6010 for general purpose. Believe it can't be done.
Regards, Rich Smith
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There are many web sites like this with strength calculators and material properties. https://www.roguefab.com/tube-calculator/
You need some familiarity with the mathematics and vocabulary of "Statics" to make good use of them. https://en.wikipedia.org/wiki/Statics
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On 1/18/2020 11:18 PM, Jahan wrote:

How is this not a "duh"? The U channel is basically 1/2 the tube (3.2" x 1.2").
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