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  1. MrMyers

    Symmetry with the workbench

    You need to consider two things before you use symmetry: - Is the geometry symmetric, and, - Is the thermal load symmetric Thermal symmetry can be considered the same as a perfectly insulated wall. If your results aren't behaving, then one or both of the above requirements is not satisfied...
  2. MrMyers

    Pipe elbow stress modelling

    Take a look at API-579/ASME FFS-1. What you are trying to do is considered a "Level 3" analysis. However, there is such a thing as a "Level 2" analysis which does not require the use of FEA, and is ananalytical approach you can do on a spreadsheet. I'd start with a Level 2 analysis, and only...
  3. MrMyers

    FEA; When should we activate large deformation?

    Run both cases and check the difference in results. If there is a difference, you probably need to leave large displacement turned on. If your stresses are above the yield strength, then also consider including non linear materials (plasticity). Where codes/standards support design by...
  4. MrMyers

    Shaft defect, crack or weld

    Can you take a metallurgical replica to investigate the grain structure at high magnification.
  5. MrMyers

    Prestressed CYCLIC Harmonic Analysis in ANSYS

    I have a feeling that it is not possible to do what you are attempting in workbench. It is possible in Classic, however. One approach may be to conduct your harmonic stress analysis at 0RPM, and later manually adjust the frequency of response to be closer to what your natural frequency...
  6. MrMyers

    "Extrude Cut" in DesignModeler 12.1

    You'll need to (1) make a new sketch on the starting plane, (2) draw your circle for the hole cross section and (3) extrude as a cut (Select 'cut material' instead of 'add material')
  7. MrMyers

    ammonia-steel

    Carbon steels in anhydrous ammonia service can suffer from stress corrosion cracking if the water content is less than about 0.1%, with the presence of oxygen (also small ppm). There is some good information available from European Fertiliser Manufacturers Association (EFMA) about this. I've...
  8. MrMyers

    Local metal loss assessment of piping elbows

    You may want to consider referring to API-579/ASME FFS-1, which offers many levels of procedures for computing the remaining life of thinning components. The procedures allow walls mildly thinner than design code 'minimum thickness', depending on the situation and level of knowledge of the...
  9. MrMyers

    Steam turbine rotor cracks

    I don't want to sound like a salesman, but I've previously been involved with the assessment of cracks and flaws in turbine discs. We've developed some fancy procedures to assess the integrity and remaining life. Furthermore, I'm located in Brisbane. Further to what thgirw said, you may get...
  10. MrMyers

    applying reaction forces of one model onto another model

    In workbench, it's probably done by using 'Remote force', this lets you tie all the nodes on one contact surface to a single node located elsewhere (you specify the x,y,z of this new point) - apply your force to that remote point to achieve distribution of said load across the surface you've...
  11. MrMyers

    applying reaction forces of one model onto another model

    Omidomidi, You will probably need to run a full contact solution here - the reason is because of the non-linear load sharing between each steeple 'branch'. Imagine if the blade was modelled as rigid - the peak stress will occur on the disc's lowest fillet - but if both are modelled as elastic...
  12. MrMyers

    applying reaction forces of one model onto another model

    You'll need to think about your actual situation- how are the blades attached to the disc you are modelling? Also, what are you trying to achieve? Stresses at the blade root/attachment, or far field stresses? Is it a blisk where the blades and disc are machined from one piece? - You'll...
  13. MrMyers

    Another ABAQUS vs ANSYS topic

    Thanks, I am not yet familliar with the different Ansys packages, but I understand they run "Ansys Mechanical", "Ansys Professional" and "Ansys Multiphysics" (Dyna, CFX, Autodyn etc). Cheers
  14. MrMyers

    Inputing Material Data with diff compressive and tensile stiffnesses

    See http://www.eng-tips.com/viewthread.cfm?qid=211773
  15. MrMyers

    Another ABAQUS vs ANSYS topic

    In a couple of weeks I will be starting a new job with a company who primarily use ANSYS suite. My expertise has previously focused on Abaqus, in the areas of thermo-mechanical stress, contact, fractures etc. Apart from the usual familliarisation with the software, what, in your expert...
  16. MrMyers

    Quantifying value of legacy shot peen on pinion

    As mentioned above, peening is used in a wide range of industries, however, as far as I am aware, its affects are not often quantitatively used in an analysis to prove design life of a particular component. The life of the component is predicted based on other methodologies without taking the...
  17. MrMyers

    Liner bulge in pressure vessel

    As corrosion has been identified as the cause of the apparent bulges, liner thinning will likely continue given the corrosivity of the process, I have seen zirconium used in place of 316L, however very expensive. Interestingly, I've seen damage in a similar reactor - so I draw your attention...
  18. MrMyers

    Problem modeling a seam in 3D

    Have you tried assigning a seam? Interaction > Special > Assign Seam. You will then have to work through your crack manager to assign a crack tip, quarter point nodes etc. You'll need to do this after meshing and also go back to your step module to write your K/J values to the odb as this is...
  19. MrMyers

    Follow nodal rotation

    As an even more general guess - "Follow nodal rotation" has invoked the nlgeom procedure, the force you are applying is above the buckling load and therefore an unstable problem?
  20. MrMyers

    Detecting cracks in metal

    You should also think about why these 'cracks' are present. Questions to answer are: 1. Are they welding flaws - lack of fusion, slag etc? 2. Are they corrosion related (all sorts of water quality/material selection issues open up) 3. Is the design in need of attention to avoid features...

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