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  1. sdra2

    EN ISO 13849-1 MTTFd

    Hello In this standard, safety-related parts of control systems, what does the 'd' of MTTFd mean? I know it means "dangerous (failure)", but it also talks about a safety system failing to operate. If a safety system failing to operate places the machine it is protecting into a default safe...
  2. sdra2

    O-ring E515-80 compatibility to N2H4

    Trelleborg chemical compatibility chart says EPDM - Hydrazine - Very Good Suitability. Phone them and see what applications experience they have!
  3. sdra2

    Yield in Material

    Doesn't answer your question directly, but might help... Also, look at the same link with a "15" at then end. I don't think there is a "standard percentage" like you are after.http://www.nafems.org/resources/knowledgebase/014/
  4. sdra2

    How far from a singularity is far enough...

    321GO In response to your post... 15 Apr 10 13:26. I think you can work upto about 25% rather than 50% before the curves diverge, so upto around 25% of UTS you should be fine with your linear model. If you end up having to do some fatigue analysis, remember my earlier point about grey iron...
  5. sdra2

    How far from a singularity is far enough...

    With rb1957 here. You seem to be reporting a "stress level" of 113MPa for grey iron, UTS 250MPa using a linear run. What you've actually got is a stress level for an elastic material for whatever E you've typed in. Stress-strain curve for grey iron isn't linear, and there is a massive...
  6. sdra2

    EN 13445 - Copper

    Hello Does EN 13445 pressure vessel code cover copper alloy fabrications? I see that PD5500 does, as does ASME. Hope someone can help.... Thanks
  7. sdra2

    Stretching a Torus - Maths Problem

    Trelleborg have what I think you're after in their O-ring guide. Need to register with them to view it. Cheers
  8. sdra2

    Autodesk Inventor Routed Systems

    My company is looking at purchasing this software. We currently have seats of Inventor where we can create pipes, adaptive or otherwise, with 3D sketches. Could anyone offer some experience-driven opinion please on what there is to gain from upgrading: for example, what can you do with Routed...
  9. sdra2

    Bolt modeling in Workbench

    If you look at your "solution output" or "solution convergence" graph (can't remember the exact terminology, sorry) you should see two traces. These overlap when the solution has converged. For a bolt load analysis, the two traces have to converge twice: once for solving the bolt preload, and a...
  10. sdra2

    Bolt modeling in Workbench

    What is the "rigid body motion error"? I think Workbench adds what it calls weak springs to remove rigid body motions and I seem to remember it doing this for bolted joints more often than many other types of analysis. If it has done this, I think (from memory, not used Workbench for a while)...
  11. sdra2

    Bolt modeling in Workbench

    Well, I would start off with some small clearance around the bolt and ensure that there is no contact here. I'd then make sure there was a "split cylindrical surface" on the bolt shank where it is clear, and put at least 2 or 3 mesh elements lengthwise on this split surface. For your load apply...
  12. sdra2

    Bolt modeling in Workbench

    Is the bolt going through a clearance hole (it needs to)? Do you have a discrete cylindrical surface 'free in space' that you have applied your bolt load to, or have you applied it to the whole bolt shank? Is there a nut on the other side of the grey bracket, or is it a blind hole you're...
  13. sdra2

    Autodesk Inventor FEA?

    Engaddict How can you acquire or actviate the Algor trial within Inventor?
  14. sdra2

    PED 97/23/CE substitude with ASME VIII

    ASME VIII and PED are not the same sort of thing - if you are familiar with ASME VIII and read the PED you will see what I mean. This link may not be up-to-date, but it is a good start. Look at section 2.2.3(a). You can most likely use ASME VIII design rules to help you towards PED compliance...
  15. sdra2

    Lab torque test question

    Torque is not a good indicator of applied load for a bolt. With all other things being equal, you can expect a variation of +/- 25% for actual applied load using a wrench. Is this how you are applying your load? Turn-of-nut is better, where you measure the angle turned by the nut. Measuring...
  16. sdra2

    FEA code with different tension / compression Young's moduli

    Oops, almost forgot - I think I recall that the first data points that you enter for both the tensile and compressive curves have to define an equal Young's modulus in effect, but you can set this first part of the curve to be very near the origin and then do whatever you wish for the rest...
  17. sdra2

    FEA code with different tension / compression Young's moduli

    Hello I don't know anything about taramide at all, but I do know that ANSYS has a cast iron material model that allows the user to input different stress-strain curves for tension and compression. Page 172-182 of the attached link gives some info on this. Perhaps it can be adapted to your needs...
  18. sdra2

    Bearing Life

    Found this, but can't vouch for it I'm afraid - might be worth a look though? Scroll down to calculation C.4. http://www.tribology-abc.com/calculators/
  19. sdra2

    ANSYS Design Space Reation Load Calculation

    I think DesignSpace has moved on a few revisions since I last used it but, from memory, if you have a solved analysis then either:- (a) click on any constraint in your "model tree" and the reactions are reported in a sub-window somewhere or (b) right click on the constraint and it will give...
  20. sdra2

    Small pump for liquid pentane

    Thanks fellas - I'm checking out all of your suggestions!

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