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Recent content by gfbotha

  1. gfbotha

    Thickness effect in crack-tip stress analysis

    Hallo again, Csmanien. Yes, to my diffidence, I have to agree about 3D elements being the applicable element type for this purpose. Mislead myself by the thought of having to specify thickness in case of plane stress, and not so for plane strain! By second thought I agree that although the...
  2. gfbotha

    Thickness effect in crack-tip stress analysis

    Hallo In my opinion you need to use plain stress elements to model the different specimen thicknesses, and, both material (plasticity) and geometry non-linear effects should be simulated. As the load increases, you must be able to see the stress rising until it reaches the specified yield...
  3. gfbotha

    Should I mask the bore of a bearing housing for anodizing

    You might like to have a look at a standard like MIL-A-8625; it tries to address most of the issues you mention. Fatigue properties are generally reduced by the brittle anodizing. A recommended allowance for the expected dimensional increase = 1/2 thickness of the anodizing...(but, as jgKRI...
  4. gfbotha

    Principal stress in plastic region

    Hallo Marc Nicely described question. I think what is happening, is that although the part is in tension in say the x-dir., there is developing a tensile stress in the perpendicular or y-dir. due to Poisson's ratio (it wants to contract but is restraint from doing so by say a strong shoulder)...
  5. gfbotha

    Tower Anchor Bolts with Leveling Nuts below the Base Plate

    UcfSE; Maybe...? [wink] Yes, designing/allowing for fatigue (lower allowed stress levels) is what I hinted in my previous post. Designing for fatigue brings along more uncertainties (e.g. w.r.t. loading). As said, it just appears to be questionable or less robust practice - granted...
  6. gfbotha

    Tower Anchor Bolts with Leveling Nuts below the Base Plate

    Without levelling nuts below, one can tighten / re-tighten the nuts after the concrete/grout has set in order to generate a proper preload. It has to be noted that the modulus of concrete is say ±6 times lower than that of the bolts, allowing a significant length of the bolt to participate...
  7. gfbotha

    Tower Anchor Bolts with Leveling Nuts below the Base Plate

    Thanks 'SlideRule' for confirming the practice. I can certainly see the benefits of not grouting but am actually more concerned about no preload and therefore the possibility of fatigue failure... Especially given the stress concentrations present in the bolt threads. Other considerations...
  8. gfbotha

    Tower Anchor Bolts with Leveling Nuts below the Base Plate

    Thread507-42018 has reference. The practice of having a (tower) base plate resting on levelling nuts, and more than often, also without filling up below with grout, keeps bugging me... As pointed out in the referenced thread, one could take measures, and even do maintenance, to protect the...
  9. gfbotha

    Extruding over features to eliminate

    To correctly model different production stages involving some very specific manufacturing steps, where say both stages do have its corresponding configured drawing, I figured 'extruding over' as a proper way to do it - but, that is only after having started a new part linked via Insert > Part...
  10. gfbotha

    Modelling Roller and Plate in 2D

    M-Flyo Capturing deformation / all effects in the specific view mentioned, would require full 3D (see tip by Mustaine, not only equal but also thickness counts) but you could build a 1/4 model.. Maybe, except if the roll really has a very, very large relative size (I would say more than that...
  11. gfbotha

    What is the future of FEA softwares?

    Hallo Greg I fully understand and agree with you about the concern that a draughtsman, or designer (not experienced with structural analysis as such), might cause expensive errors to happen. And, that CAD integration increased the chances of this to happen (purely because of the FEA being...
  12. gfbotha

    Model edge lines on (deformed) contour plot

    Hallo "APav" You know your story..! - thanks a lot! This little bit of functionality already evaded me right from the beginning when we started using Femap. I tested the method as proposed and could see why you call it "weak", but it gives me 80% of what I need - enough to live with I...
  13. gfbotha

    Model edge lines on (deformed) contour plot

    Hallo all Does any one perhaps know how to show the edge lines of a 3D model on a stress contour plot? (also in case of a deformed model/geometry). I am only aware of the Filled Edges setting; but, it plots lines representative of all element edges (not only for edges lying on the model...
  14. gfbotha

    Hyperelastic Inputs

    Hallo Andrew I do not want to unnecessarily cross-post; do you perhaps have access to Siemens GTAC support forum "Femap Misc"? - because there I recently responded to a similar question offering a simplified approach you might like to consider. Say if you do not get right. You might...
  15. gfbotha

    Why do you like Femap?

    Hallo trainguy Well, opinions differ - for say 25 years already I am doing FEA in-between all my other tasks as mechanical engineer. Let's say at least once a month, sometimes for two weeks continually. I started with EMRC NISA - had to keep cryptic notes/tips/guidelines for each type of...
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