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MikeMcMullen
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Comments
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I agree the cutting plane is fiddley, especially with a large model.
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That might work well for the vehicle. They deform 6"-12" during crash tests. The bridge rails, not so much. Deformations may be as much as 6", but strains are usually well under 1%.
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OOH! this looks just right for me!! Smashing bridge rails here I come.
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Never mind. Concrete cracking never got to the rebar with the tension capacity.
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Got a model to run to 100% (attached screenshot). I increased the Tension limit 10% on the Compression only concrete material and it ran to completion. Previous run had only gone to 65% before it failed to converge. I had thought a problem at the…
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Other runs have not crashed. I am currently running a smaller model (changed elements to linear from quadratic). issues (worked and working around): Quasi static will not work because I have several different pressure loads on some areas simultaneo…
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What would be the specific instruction to get this "last iteration thing". I was out of the house and it seems to have erased all the output and closed mecway when it finally stopped when I was gone. (doesn't always do this) and I could not find s…
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My problem was simpler than that. The black solid lines at the edges of the bars overwhelmed the colored interior when not zoomed in, and with a regular grid of bars top and bottom it is hard to keep orientated with what you are looking at. I. e. …
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Both areas of concern for me. Once I get a run far enough for significant stresses, maybe at least touching yeilding I can look close at the output. My supports are not compression only, but elastic. This will tell me about any uplift issues when…
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I have done that before, but I don't think it would help much in this case as the increment quickly gets down to 1% or so then starts working up slowly gradually getting more slow as the stiffness falls and non-linearity increase. Still would need …
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Not in good enough shape yet. I think the above may do the trick. Bit of effort to make the loads "time" dependent. Thank you. I was sure you had an answer.
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It seems to go the same with quasi static reguardless of the values I input. It does ramp the loads gently with or without quasi static, just runs out of allowed iterations at varying points for the same input. I think the one that went to 87% may…
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I don't expect a quick convergence. As the load increases the depth of the cracks in the concrete increases and the length too, and this changes the stiffness which changes deflection, and loads the rebar as the crackiing passes the rebar but eferyt…
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I have run into this as well. Perhaps some sort of changing of the resolution settings where the resolution is lower when moving/rotating, and increasing resolution again when not or when slower motion.
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Some very high strength bolts such as used in aircraft and some machinery have a reduced shank to keep the stress lower in the threads, because of the strain concentration at the root of the threads aggrevates fatigue, and have a fillet under the he…
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I get it too. Currently working about 1/4 time as a temp at the employer I retired from in 2003. Using new Mecway release to check the effect of a cosmetic change to a bridge rail.
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Beyond me. Not a materials engineer, especially those for which Mohr columb is used for. Also the soils examples I was exposed to were always 2D, or simplified to reduce to approximately 2D. All real tests involve 3D interaction though.
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Actually when concrete cracks in shear the shear stress field rotates putting the crack in some compression. This is what makes Mohr Columb useful, and also what has made concrete analysis in shear difficult after cracking. Currently, for bridges …
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I think you are correct...There is no single tensile stress at failure unless you are dealing with a one dimensional problem. I have no insight for improvement.
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The paper is quite helpful. The recommend values are also reasonably consistent with recommended values I have seen. Good luck on the example problem!
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Note that I actually do not use FEM for dealing with "allowable" stresses in concrete as these have been set by codes based on much simpler calculation methods before FEM was well developed, and may be narrowly applicable. I use it for problems out…
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For this example, of flexure in a solid beam, the tensile strength used normally would be "modulus of rupture". In reality it is dependent on the depth or volume of the tensile zone and is higher than the splitting stress as the extreme stress zone…
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Tensile strength in concrete has many definitions for concrete and in reality they vary a lot depending upon what they are used for, how they are tested, the sample size, prior strain history, and due to extreme variability compared to modern steel,…
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Ooh. That would be wonderful. Especially if it worked with Mecway. If I read the manual right it only requires a few more cards than the compression only approach, and a knowlege of the friction angle and dilation angle. There are a few examples…
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Calculix 2.21 now includes Mohr Coulomb. What we need is a good reinforced concrete example using it. It would still not include the specific non-linearity of concrete in tension and compression, but may be good enough. Some mentions from past im…
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To be expected. The first half dozen to dozen attempts are in single precision which is usually an order of magnitude faster on most machines, but about 7 digit accuracy, but in long sequences of calculations rounding and truncating errors will red…
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I have had some luck. There is an approximation for the tensile strength that works ok for matching bending tests of cracked reinforced concrete that uses a tensile strength of about 0.30mpa to 0.60 mpa or so and nominal reinforcing of perhaps 0.1…
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I have a suspecion that this partly depends on the ratio between memory bandwidth and core speed. Most problems require at least the solution out of cache, usually most of the calculations, and L3 is usually shared. Looking through the literature …
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I have been using the version 23 beta for about 2 weeks with no issues related to the program, and it did pick up some badly shaped elements not found before.
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I have been looking for cracks. Note stresses seem pretty regular, just deflections, and often unusual directions. Also having convergence issues, though sometimes reaches solution, though this may be expected with the compression only concrete mo…
