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How to create a dynamic spring

Discussion in 'Using Alibre Design' started by MainJet, May 29, 2018.

  1. MainJet

    MainJet Member

    Is there a way to create a dynamic spring that will compress/expand in an assembly ?
    I can draw a fixed spring just fine
     
  2. Lew_Merrick

    Lew_Merrick Alibre Super User

    Not really as that would require a dynamically linked reference Plane set to control the Helix definition. What I do is to create Configurations for Free Length, Initial Compressed Length, Fully Compressed Length, and at least one Intermediately Compressed Length. It is then only an "issue" to activate the correct Configuration within the Assembly. [Not, mind you, that this has not neen part of my List of Requested Improvements for quite a while.]
     
  3. MainJet

    MainJet Member

    Thanks, I was afraid it would be something like that.
    I need to figure out the absolute minimum clearance required for the spring, but the spring is also bending a bit.
    Aware of any software around that will do this sort of stuff ?
     
  4. Lew_Merrick

    Lew_Merrick Alibre Super User

    Have you noticed my Spring Design "resource?" There's one for coil compression springs and another for hairpin double torsion springs. Both meet SAE and DoD requirements.
     
  5. bigseb

    bigseb Alibre Super User

    I do this using configurations in some mould assemblies. Its not dynamic but close enough for my purposes.
     
  6. MainJet

    MainJet Member

    Thanks for the above.
    Lew, where is the Spring design resource ?
    I usually draw it myself but it is always good get something which is easier :)

    The issue I had was to bend the spring inside the the assembly to ensure enough clearance.
    Bugger all wall thickness to work with so the more I can leave in the better
     
  7. simonb65

    simonb65 Alibre Super User

  8. B Castle

    B Castle Member

    A dynamic spring is out of my price range. But if anybody would like a pretty quick and dirty spring creator, I made this.
    Find a spring on MSC or equivalent.
    Open sample spring.
    Set as read only. So Save As (SPRING PART #)
    Open equation editor
    Fill in the "A" lines (Spring OD, Wire Dia, Solid Spring Height, Desired Height for assembly)
    Does fine for 95% of everything I need, Inserts a reference plane at base and desired height for easy mating.
     

    Attached Files:

  9. TimoCAD

    TimoCAD Senior Member

    Since you want to have a deformable Part, what about FEA? There are OpenSource Softwares like Calculix or Z88Aurora or Elmer. It's a static problem if you have low velocity and low accelerations.
     
  10. Lew_Merrick

    Lew_Merrick Alibre Super User

    In essence what you would need is a Constraint with a variable range of values that allows the Helix Feature to vary based on some other Component's position. Give us that ability (angular as well as linear) and quite a few things become bettter with the Constraint system!
     
  11. B Castle

    B Castle Member

    Seems both simpler and more complex than that. You would need the centerline (axis) of your helix to be a variable spline. Then you would need to constrain each end of the spline to mate to the center point of the spring pocket I would think.
     
  12. Lew_Merrick

    Lew_Merrick Alibre Super User

    B -- My point is that Variable (within limits) Constraints are a needed improvement. Applying it to a Spiral Feature should be fairly obvious. Making that Variable Constraint driven Component as something driven by a Constrained Relationship should be equally obvious.
     
    simonb65 likes this.
  13. HaroldL

    HaroldL Alibre Super User

    Nick952 likes this.
  14. Lew_Merrick

    Lew_Merrick Alibre Super User

    Harold -- One problem associated with using S[line Entities to approximate a Compression Spring is that a spring's mean diameter increases as it is compressed. Thus, one needs to know the amount of compression to know how the mean diameter is affected. If you look at my "Coil Compression Springs Library Rev New.7z" entry under Resources you will see that being accounted for through Configurations.
     
  15. idslk

    idslk Senior Member

    Hello colleagues,

    here only a little thing for your ideas...
    springmove.zip is a very little video
    Spring_Move.AD_PRT is a little spring
    upload_2019-6-14_20-5-54.png
    and here is the little script for the "move" (should be also in the partfile)
    Code:
    Win = Windows()
    WT = 'IDSLK'
    ScriptName = 'Springmove'
    springtravel = 20
    CP = CurrentPart()
    for i in range(len(CP.Parameters)):
      if CP.Parameters[i].Name == 'D4':
        M = i
    Posi_x = CP.Parameters[M].Value
    for r in range(springtravel):
      Posi_x = Posi_x - 1
      CP.Parameters[M].Value = Posi_x
    for r in range(springtravel):
      Posi_x = Posi_x + 1
      CP.Parameters[M].Value = Posi_x
    print 'done'
    It dynamically edits the length(D4) of the spring (it does not do any FEA)
    The variable "springtravel" is to control how much the spring will be compressed and released.

    It could be made more comfortable, shiny and professional but it's only to start thinking about it...

    Regards
    Stefan
     

    Attached Files:

  16. MilesH

    MilesH Alibre Super User

  17. idslk

    idslk Senior Member

    Hello Miles,

    nice too bring this back to the light...;)
    This time it's done with only one part (helix) and using AlibreScript instead of Motion(which is no more available:()
    The smoothness from the demo today can be adjusted with the step size...

    Regards
    Stefan
     
  18. MilesH

    MilesH Alibre Super User

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