×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Spring Expanding in Motion Analysis

Spring Expanding in Motion Analysis

Spring Expanding in Motion Analysis

(OP)
I need to be able to show a spring expanding in a motion analysis study. I need motion analysis because I have some parts that have solid body contact with other parts. I want to show the whole mechanism movement in a video. Motion analysis does not allow the deformation of a spring. Is there some way I can show this?

RE: Spring Expanding in Motion Analysis

We're running SW2013 Premium edition and we have springs (compression, extension, and torsion) as one of several available options in Motion Analysis.

RE: Spring Expanding in Motion Analysis

(OP)
Jboggs,

Unfortunately, I am running SW2012 Premium.

RE: Spring Expanding in Motion Analysis

You can create "live" springs in several ways. I'll try to explain two.

In one instance you can create a sweep of the spring profile within the context of the assembly. The path sketch of the spring should be constrained to the components that are moving relative to each other. In this instance whenever Part A moves relative to Part B the path sketch will change, which will change the sweep path making it appear that the spring is compressing and expanding.

In another instance you can create an assembly of the spring from a series of half-turns of a helical sweep. If you mate the circular face of the sweeps together (coincident) and the axes together the spring will move freely as a spring should.

I can think of a couple of other ways to do this, but these are the first to come to mind. Sorry I can't send over files since I'm not on 2012.

Dan

www.eltronresearch.com
Dan's Blog

RE: Spring Expanding in Motion Analysis

(OP)
Eltron,

I have tried the first method you suggested but the part did not update in the Motion Analysis simulation. I will try the second method later today.

RE: Spring Expanding in Motion Analysis

roldy,

Since you are trying to make video and show the spring dynamically flexing with the motion of the mechanism about the only option that will work is to make a spring assembly consisting of a bunch of half coils similar to Eltron's second suggestion. As you have already discovered, the first suggestion will not work because the solid has to regenerate from a recomputed position of the driving curve, and that cannot be done dynamically in SWX at this time.

Depending on your how good the spring has to look you can make the half coils as simple as a 180 degree revolve of the wire diameter. If you need it to look smoother then the half coils should be 180 degrees of a helical sweep. Both of these techniques generally yield an acceptable appearance.

- - -Updraft

RE: Spring Expanding in Motion Analysis

(OP)
Eltron & Updraft,

I have tried splitting the spring into multiple parts but upon doing so I realized that this will not work. The end segments of the spring are to remain parallel to the ground. I have tried just having the coincident mates on the circular faces of the spring segments and a mate for the ends of the spring to be parallel to the ground. Looks like a may have to do some tricky compositing. Composite an animation video with the Motion Analysis video.

RE: Spring Expanding in Motion Analysis

You can still do it with the end segments being in a fixed position. Just mate a plane within that component to be parallel or coincident to the ground plane while leaving all other links in the spring free to move.

Dan

www.eltronresearch.com
Dan's Blog

RE: Spring Expanding in Motion Analysis

Here is an example of what they are describing in SW 2012. I used circular links. Looking at the pitch of your spring, you will likely want to use helical links. If your deformation is large, the kinks at the link may become objectionable. If that happens, you can use more than 2 links per turn. The spacer bar and links in the assembly serve to keep the links evenly spaced.

Eric

RE: Spring Expanding in Motion Analysis

Eric (EEnd),

Your model should be a great example to roldy. A star for you and your service to him.

There is, however, a simpler way to mate this and uses fewer elements. I just did the following with your model:
1. Suppressed all the Spacer Bar and Spacer Link parts.
2. Made a parallel mate of the Right Planes of the first and third instances of the Link parts. (This can be a Multiple Mate for more link segments.)
3. On the second instance of Link I made Sketch2 of Sweep1 visible, selected the center point of the circle and the Top Plane of the assembly and mated them coincident. (This, too, can be a Multi-Mate for more links.)
Done.

These changes are included in the attached file, but I am on SWX2014 so you won't be able to open it in earlier versions.

- - -Updraft

RE: Spring Expanding in Motion Analysis

Updraft,

I think I follow your mate scheme. Mating the opposite ends of the two links in a turn to the top, keeps their angle symmetric about the joint between them. Making the first links of each turn parallel keeps the pitch of the turns equal. Nice.

Eric

RE: Spring Expanding in Motion Analysis

(OP)
I will have to try this again. I will post the file if it does not work for me.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources