Dynamic Simulation Snap safety lock

[MarceloDeTomasi6989]

I have modeled a simple mechanism which it consists of a post, a carriage(80 kg), and a pivot link bar (blade+arm+tube+roundbar=weldment) (constrained to the carriaged)  with a hole at the top for the cable and 2 extension springs on the sides. Please see picture

When the cable is intact, the link arm will be vertical. When the cable snap, the carriage start its way down and the springs pull the bar behind the blade on the link arm and engage with the yellow stoppers and the carriage stop.

There is 300 mm between the stoppers. 

I have setup the system on Dynamic Simulation  with one prismatic joint between the carriage and the post, 1 revolution joint between the link arm and the carriage bracket, and a 2D contact between the blade and the stopper

In new some advice to see if the setup joints are the correct ones to determine:

1. The Spring stiffener factor the keep the link vertical when it is working in normal condition, and at the same time have a fast reaction time(the spring).

2. The time the blade will take to hit the post. Will the blade bounce so will jump the stopper? I have use a 0.2 restitution value but I am not sure about this one.

 3 When I run the simulation, it seams that it work OK but I am not confident as I havent use DS to often. What I notice is that the blade get into the post wall at the end of the simulation.

and the bottom line is Will it work?

If somebody can have a look at the setup an make any comments I will greatly appreciated.

Dataset is 4.6Mb - Not Included.

Inventor Pro 2013-64bit edition

Build: 176, SP1.1

Marcelo

[MarceloDeTomasi6989]

I will like to include the dataset in a compressed file after P&G, so somebody can have a look at my problem but I have some technical problem with the extensions and the sizes. Is any FTP available to upload the files?

Zip files is 3.3Mb

Thanks.

[henderh]

Hi Marcelo,

  I'm still trying to wrap my head around the mechanism design / function.

 Can you try zipping up just a few of the files at a time, using multiple posts to stay under the attachment limit?

Thanks, -Hugh

[MarceloDeTomasi6989]

Hello Hugh,

Thank you for your emails.

I hope you can understand better the setup as I am sending the assemblies and parts.

This will be 1 email of 2 so I can upload all files.

[MarceloDeTomasi6989]

Hugh, this one is email 2 of 2.

Regards.

[MarceloDeTomasi6989]

Hi Hugh,

I have posted the files on the forum a few days ago. Did you have any
chance to have a look to the setup?
Thanks.

Regards,

Marcelo De Tomasi
Industrial Engineer

3D Engineering Design
www.3D-Design.com.au

Sunshine Coast, Qld, Australia, 4561
Office 0754 467607
Mobile 0427 467607

[henderh]

Hi Marcelo,

  My apologies, I didn't notice the update until now.

  There are still missing files.  The top-level assembly (SAS-A01-Analysis ver-2) isn't contained in the zip files.  Also, there are missing component references when opening the other assembly files.

  If you do a 'Save-As => Pack and Go' while the top-level assembly is open,  it will assure that all the necessary referenced files are included.

Thanks, -Hugh

[MarceloDeTomasi6989]

Hi Hugh,

I have done a new P&G from the main assy as you suggested. Hope this time
will work.

Thank you very much for your intervention.

Regards,

Marcelo De Tomasi
Industrial Engineer

3D Engineering Design
www.3D-Design.com.au

Sunshine Coast, Qld, Australia, 4561
Office 0754 467607
Mobile 0427 467607

[MarceloDeTomasi6989]

Hi Hugh,

Its looks the attachment didn't work again maybe it is to big. I tried to split it into 3 files (2x1.424Mb and 1x.487 Mb) but it added a 001, 002 and 003 to the extension and I am not allowed to do it. Is there any other simple way?

Thanks

[MarceloDeTomasi6989]

Hugh, I have attached the missing assy file. You may be able to put it all together.

Regards

[henderh]

Hi Marcelo,

  I opened the top-level assembly and the following parts are missing:

SAS-C19-01.ipt

SAS-C01.ipt

SAS-C02.ipt

SAS-C12-01.ipt

SAS-C15.ipt

SAS-B07-02.iam

ISO 2341 - B - 12 x 85DIN EN.ipt

DIN 1850 - G - 12 x 16 x 20 x 13.ipt

SAS-B06.iam

  You can either package them up into small enough zip files to stay under the attachment limit, or share them using your Autodesk 360 account (360.autodesk.com)

Thanks! -Hugh

[MarceloDeTomasi6989]

Hi Hugh,

I have collected the missing parts in a zip file. I must posted (earlier) the full assembly rather than the simplified version. Anyway, all files are available now. 

Thank you! - Marcelo

[henderh]

Hi Marcelo,

  Now that we have the sub-assembly SAS-B06.iam, Inventor is asking for the components of SAS-B06.iam:

SAS-C22-02.ipt

AS 1237 - 16 mm(5).ipt

AS 1427 - M10 x 20(4).ipt

SAS-C22-01.ipt

AS 1237 - 16 mm(5).ipt

AS 1427 - M10 x 20(4).ipt

SAS-C22.ipt

  Even with these components missing, I can still open the top-level assembly, skip the missing components and Dynamic Simulation doesn't seem to be complaining.  But I'm not sure if they are needed.

Thanks, -Hugh

[MarceloDeTomasi6989]

Hi Hugh, Those parts belong to a different configuration and not needed for this analysis. Please see the picture attached for B06 parts list.

Thanks - Marcelo

[henderh]

Hi Marcelo,

  I was able to spend some time on this today.  Please see attached files.

  Your approach of using two 2D contact joints is correct, so the blade will not penetrate the main vertical post and will also hit the stopper.  I created a sketch in the post component of a rectangular profile to be used in the 2D contact joint (this is why I attached the modified post component).

  Next, to simulate the cable and it snapping, I used a spring joint.  The endpoints of the spring are between the hole in the lever and a workpoint tangent to the pulley (the added workpoint is why I attached the modified pulley part).  We can use the input grapher for the spring stiffness to act as a tension spring for a short time, then make the stiffness go to zero, simulating the cable snapping.

  This is as far as I could get today, I hope this helps get you further along.

Best regards, -Hugh

[MarceloDeTomasi6989]

Hi Hugh,

Thanks for your input in the problem.

The spring you have added representing the cable and snap simulation. That is something I never will guessed.

I have a message on the side springs(Side Spring Joints) saying "Missing entities in joint edition" which I don't know what it means. Still works.

The 2D contact you have added stops the blade going into the RHS wall. Good stuff.

Now, I need to "size" the side springs to get the blade engage within the 300 mm pitch between stoppers when the cable snaps. I have changed the stiffener of the side springs and looks that around 8 N/mm it will be ok but I am not sure. Can you please give a guide line for this?

The 2 x side springs should have less traction force then the horizontal component on the top hole of the lever when the cable is intact.

Will the blade engage in the lock when manually lowering the carriage, due to the springs pulling the blade?

So the size of the springs (stiffener) will be that works when manualy lowering the carriage and when the cable snap.

If you can clarified my queries will be great.

Thanks! Marcelo