topic Re: Help with Dynamic simulation in Inventor Forum

Help with Dynamic simulation

Yashasvi23481 — Sun, 20 Jan 2019 22:30:35 GMT

Hi All,

I am trying to learn dynamic simulation to test movement of an assembly with effect of wind speed, where every part can move and tip over. I want to know if particular assembly will stand or tip over. If at all, it moves what will be displacement. In normal stress analysis, some point has to be fixed but effect of wind will be on all parts.

Through my previous posts, I was suggested to use Dynamic analysis, so I am entering into foray for first time. I am presenting you the assembly and need to know how to go about doing analysis. Being first time, will be good if I can get step by step instruction. I searched online but cudnt get similar assembly to aid. Ignore the fasteners/ skip them when prompted. Force applied is on slant face. I am in dynamic simulation environment and all terms are new to me. joints have replaced constraints. Please help.

Regards,

Yash

Re: Help with Dynamic simulation

JDMather — Mon, 21 Jan 2019 13:13:09 GMT

https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=wasim+younis+inventor

Re: Help with Dynamic simulation

Yashasvi23481 — Mon, 21 Jan 2019 22:00:00 GMT

Hi JD,

Thanks for suggesting the book. I wanted personalised help that's why I shared my model. It is bit urgent but I will buy it and develop right now I am down with time.

Thanks and Regards,

Yash

Re: Help with Dynamic simulation

Yashasvi23481 — Tue, 05 Feb 2019 05:17:26 GMT

Hi All,

I have this assembly. I am missing one revolution or cylindrical constraint. All I need to do is apply load on top circle indent (to create surface) with 450N and see it spin in a way that it stops where the stopper is. I am doing something wrong and I cant figure out what.

Its the case of dynamic simulation. I have gravity defined and loads applied but it doesn't behave the way I want. All I want to test is whether pivot point is high enough to ensure the popper resets due to weight. Please see attached zip file. its in 2018 version so please if you are solving, show me in screencast what step I am missing ? Need urgently by tomorrow if possible. if you are editing, ensure its in 2018.

Thnk you for help in advance.

Regards,

Yash

Re: Help with Dynamic simulation

mikejones — Tue, 05 Feb 2019 10:52:21 GMT

Hi Yash

First of all I'd suggest you change the cylindrical joint to a rotational one with a 1mm gap setting the spacing between the parts. This is the only constraint / joint that you need. Remove the contact set from the parts too. In the DS area, you need the 3d contact between the two parts but you need to look at the stiffness and damping values associated with the contact; think of it as a spring. Set the stiffness and damping values high so that the motion stops as soon as contact is made. That should do it

Edited

Just re-read your post. You're simulation is to check that once the 450N load is removed the popper returns to the resting vertical position, right? From what I can see, once the load is removed it stays where it is meaning there isn't enough weight in the popper to return it to the vertical position. If you remove the 3d contact joint and run the analysis the popper rotates in the direction that the initial load rotates it. The pivot point needs moving up. Also bear in mind that you have effectively created a friction free joint that you will probably need to address with some friction forces.

Mike

Re: Help with Dynamic simulation

JDMather — Tue, 05 Feb 2019 12:36:17 GMT

You have a redundant assembly constraint that does not make logical sense.

With the correct assembly constraints - you should have one Revolution Joint (see image).

How long should the 450N be applied (I assume you will want to set time in Input Grapher).

I will probably change the 3D Contact to 2D Contact since the part is already constrained to one degree of freedom. (Revolution in a plane.)

Re: Help with Dynamic simulation

JDMather — Tue, 05 Feb 2019 18:49:38 GMT

Sorry about the audio level on this.

I went back and recorded the video again with better audio level, but in the process found a mistake that I made.

This might get you started in the right direction while I track down the source of mistake that I made.

Re: Help with Dynamic simulation

Yashasvi23481 — Tue, 05 Feb 2019 21:15:43 GMT

Hi JD & Mike,

Thank you for help and screencast video. Gives me lot of relief. To answer your query about time the force is applied its just a second or 2 as bullet is shot at it. its not continuous force but impact. Head is stopped by support behind.

@mikejones Is rotational found in joint or regular constraint tab ? I will have a look at video and apply them on my assembly.

Thanks again for personalised instruction and help.

Regards,

Yash

Re: Help with Dynamic simulation

Yashasvi23481 — Tue, 05 Feb 2019 21:25:18 GMT

Hi JD,

The lead part added below popper is for gravity ? Cant we apply gravity in that direction or does it need surface ? Can gravity be applied at bottom edge ? Another thing is, original position is popper sitting nearly vertical not at angle.

Video has shown all I wanted. Being novice, need to find command buttons and right constraints to apply.

Regards,

Yash

Re: Help with Dynamic simulation

JDMather — Tue, 05 Feb 2019 21:25:22 GMT

@Yashasvi23481 wrote:

... its just a second or 2 as bullet is shot at it....

I suspect that even 1 second is much longer than actual time of impact.

Re: Help with Dynamic simulation

Yashasvi23481 — Tue, 05 Feb 2019 21:37:55 GMT

Hi Mike,

Found the rotation joint. I have removed contact set too. where do I find damping and stiffness ?

Regards,

Yash

Re: Help with Dynamic simulation

Yashasvi23481 — Tue, 05 Feb 2019 21:54:02 GMT

Hi JD,

Sorry for too many questions but what are 2D contact I mean which 2 surfaces have you selected ?

Regards,

Yash

Re: Help with Dynamic simulation

Yashasvi23481 — Tue, 05 Feb 2019 22:15:55 GMT

Hi,

This is Navigation window I achieved. Even after doing contact set or removing them, it is rotating full circle.

Re: Help with Dynamic simulation

Yashasvi23481 — Tue, 05 Feb 2019 23:15:52 GMT

Hi JD & Mike,

Appears that we are in different time zone. So here is further list of query I have to achieve my results.

1. How do I get harmonic ramp in the magnitude graph ? currently I have only Linear ramp.

2. How do I limit the motion of popper plate between 2 surfaces? As seen in previous post, its going past the stopper.

3. Once I get dynamic simulation done, how do I generate report, I mean what do we do after exporting to FEA ? Whats next step to come to conclusion the effect of the force on popper ?

4. What 2 D joints have you used as I am getting error while doing them.

I will check my email again tomorrow or before but I have something parallel to do. This example will be applied to other similar rotational assemblies so getting this right is very important. I will not raise another post for those assemblies as they are on same line. Help me with this assembly to completion I will need to produce reports by Friday for all 4 assemblies this being 1 of them.

Thanks and Regards,

Yash

Re: Help with Dynamic simulation

JDMather — Wed, 06 Feb 2019 00:23:13 GMT

@Yashasvi23481 wrote:

3. Once I get dynamic simulation done, how do I generate report, I mean what do we do after exporting to FEA ? Whats next step to come to conclusion the effect of the force on popper ?

What is your purpose for doing the analysis - exactly what do you want to know?

Re: Help with Dynamic simulation

Yashasvi23481 — Wed, 06 Feb 2019 00:30:44 GMT

Hi JD,

What I am trying to achieve is safety factor and whether it will withstand that force and deformation caused ? Can dynamic simulation be converted to report like stress analysis ? Why is there an option called export to FEA ?

Regards,

Yash

Re: Help with Dynamic simulation

Yashasvi23481 — Wed, 06 Feb 2019 21:16:59 GMT

Hi JD,

To achieve dynamic simulation like yours I am missing few bits.

1. What are dimensions of the part called weight in your model ?

2. How do I achieve Harmonic loop in the magnitude graph ? when I do click + it only adds linear loop.

3. Where have you applied gravity ? I tried on the moving part and it says you cant apply gravity on moving part.

4. How do you control the movement of rotating part so it stops at either end ?

5. What are 2D contacts you have used ? in video it just shows the stand.

6. I believe I can save simulation video using publish option.

To save answering these questions, can you please send your model with dynamic simulation so I can see how to apply. This video shows after dynamic sim you export to FEA. That's why I asked.

https://www.youtube.com/watch?v=aaM7BBEUgVE&feature=youtu.be

Regards,

Yash

Re: Help with Dynamic simulation

JDMather — Wed, 06 Feb 2019 21:34:39 GMT

I have been sick last couple of days an not thinking clearly.

1. The counter weight can be whatever size you need depending on the material you use.

2. The motion law can be whatever you want - I would have to investigate projectile collision to determine what it should really be.

3. Gravity is applied globally, not to a part. But you can use a stationary part to define direction of gravity.

4. 2D Contact - this is covered in the Wasim Younis book. The movement is result of projectile force.

5. See #4

6. I think you mean Export to FEA, but not sure. If so, yes you can export the Motion Loads to FEA. This is covered in the Wasim Younis book.

If you mean the motion animation - you can Publish to Studio and do additional animation (like camera motion, zoom, pan - whatever you need).

It might be several days till I feel well enough to correct the mistake that I made in my initial attempt and post the files. (I still need to add a Point-Line and test the Export to FEA to make sure that I have everything set up correctly.) I am a bit concerned about what you really hope to demonstrate with the analysis as Inventor FEA is limited to slowly applied loads, not impact forces. So while we can represent the motion and Export to FEA, I am not sure that is really going to return the information that you are after.

Re: Help with Dynamic simulation

Yashasvi23481 — Wed, 06 Feb 2019 21:52:02 GMT

Hi JD,

That's detailed explanation. Thank you. Hope you get well soon. To cut short, if I can get dynamic simulation working, I can take screenshots for reports if required.

I await your response. Have you done dynamic sim in 2018 version ? if so, can you please send me the zip file of updated assembly ? See the video of simulation.

Thanks.

Yash

Re: Help with Dynamic simulation

Yashasvi23481 — Wed, 06 Feb 2019 22:17:59 GMT

Hi JD,

This is error I get when I apply 2D contact. It does stop at 2 places as in your model in free mode. but cant run simulation. I think I am very close to get the simulation working. Need to fix 2D contact. I will try playing with it selecting various planes and edges. I managed to get harmonic loop in the magnitude. so getting close.

Regards,

Yash