FAQ  •  Login

Adams Assignment 4

<<

F11Jonathan

Newbie
Newbie

Posts: 29

Joined: Mon Sep 12, 2011 7:58 pm

Unread post Sat Oct 15, 2011 2:40 pm

Adams Assignment 4

On page 14 of the Adams Assignment we set the speed to 360 Degrees per second (360D), on page 16 we set the duration to 2 seconds. The note on slide 16 says that if everything is done correctly the simulation will complete 1 revolution. My simulation completes two revolutions because 360 degrees/s times 2 seconds is 2 revolutions. Is the speed or duration wrong, or is the note on the slide wrong?
<<

F11Jonathan

Newbie
Newbie

Posts: 29

Joined: Mon Sep 12, 2011 7:58 pm

Unread post Mon Oct 17, 2011 10:23 am

Re: Adams Assignment 4

How do you apply a step motion? I used STEP( TIME , 0 , 0d , 1 , 720d) as the function in the joint motion, but it does not appear to be stepping the motion which would require infinite torque and should give an error. Are my inputs wrong for the STEP function?
<<

TobyH

Newbie
Newbie

Posts: 39

Joined: Wed Sep 03, 2008 12:26 pm

Unread post Mon Oct 17, 2011 2:01 pm

Re: Adams Assignment 4

F11Jonathan wrote:On page 14 of the Adams Assignment we set the speed to 360 Degrees per second (360D), on page 16 we set the duration to 2 seconds. The note on slide 16 says that if everything is done correctly the simulation will complete 1 revolution. My simulation completes two revolutions because 360 degrees/s times 2 seconds is 2 revolutions. Is the speed or duration wrong, or is the note on the slide wrong?

It looks like the note is wrong. It should do two revolutions, as you noted.
<<

TobyH

Newbie
Newbie

Posts: 39

Joined: Wed Sep 03, 2008 12:26 pm

Unread post Mon Oct 17, 2011 2:30 pm

Re: Adams Assignment 4

F11Jonathan wrote:How do you apply a step motion? I used STEP( TIME , 0 , 0d , 1 , 720d) as the function in the joint motion, but it does not appear to be stepping the motion which would require infinite torque and should give an error. Are my inputs wrong for the STEP function?


It looks like you are applying the step function motion correctly. Note that it is not a true (instantaneous) step function, as the position is specified at t=0 and t=1. It is more like a ramp function, with a smooth transition from 0d at time=0 to 720d at time=1. I hope this answers your question.
<<

F11Wendy

Newbie
Newbie

Posts: 26

Joined: Mon Sep 12, 2011 7:58 pm

Unread post Tue Oct 18, 2011 2:43 pm

Re: Adams Assignment 4

When I measure torque or force at a point my plot is a flat line at zero. I'm measuring torque at O2 and O4 in the z-axis and forces in the X and Y axes. Angular acceleration of segments seems to look fine. Any ideas what would cause this?
<<

F11Graham

Newbie
Newbie

Posts: 11

Joined: Wed Sep 14, 2011 9:56 am

Unread post Tue Oct 18, 2011 2:50 pm

Re: Adams Assignment 4

From slide 12 in the ADAMS, how do you select the point for the marker at .04,0,0? After I select the body it won't let me place the marker at a specific point since the body contains that point, it just keeps placing the marker back at the origin. Is that where its supposed to be? I ran the simulation and get the right response with the marker at the origin. I'm also having the same problem when I get to slide 18 and try to make the second triangle. I keeps putting my point at the origin.
<<

TobyH

Newbie
Newbie

Posts: 39

Joined: Wed Sep 03, 2008 12:26 pm

Unread post Tue Oct 18, 2011 4:17 pm

Re: Adams Assignment 4

F11Wendy wrote:When I measure torque or force at a point my plot is a flat line at zero. I'm measuring torque at O2 and O4 in the z-axis and forces in the X and Y axes. Angular acceleration of segments seems to look fine. Any ideas what would cause this?


You should measure the force in the joint, not the force at a point.
So, right click on the joint you want to measure, point to the joint, then select Measure (for example, for the revolute joint at O2, if you right click near O2 it would be something like "Joint: JOINT_1 -> Measure"). Then, select Force/Torque and X/Y/Z as needed.
For the driving torque, you have to measure the torque in the applied motion, not in the revolute joint. The z-torque in the revolute joint will be zero, while the z-torque in the motion will be non-zero.

If you still get zeros doing it this way, let me know.
<<

TobyH

Newbie
Newbie

Posts: 39

Joined: Wed Sep 03, 2008 12:26 pm

Unread post Tue Oct 18, 2011 4:37 pm

Re: Adams Assignment 4

F11Graham wrote:From slide 12 in the ADAMS, how do you select the point for the marker at .04,0,0? After I select the body it won't let me place the marker at a specific point since the body contains that point, it just keeps placing the marker back at the origin. Is that where its supposed to be? I ran the simulation and get the right response with the marker at the origin. I'm also having the same problem when I get to slide 18 and try to make the second triangle. I keeps putting my point at the origin.


This is an annoying problem. The issue is the 'magnetism' of the mouse to features which are already created. I believe there is a way to turn that effect off, or at least down, but I don't know exactly how. The workaround is to zoom in on the point you need to click on. When you zoom in far enough, you can click where you need to.
<<

F11Christopher

Newbie
Newbie

Posts: 22

Joined: Mon Sep 12, 2011 7:58 pm

Unread post Tue Oct 18, 2011 5:15 pm

Re: Adams Assignment 4

TobyH wrote:
F11Graham wrote:From slide 12 in the ADAMS, how do you select the point for the marker at .04,0,0? After I select the body it won't let me place the marker at a specific point since the body contains that point, it just keeps placing the marker back at the origin. Is that where its supposed to be? I ran the simulation and get the right response with the marker at the origin. I'm also having the same problem when I get to slide 18 and try to make the second triangle. I keeps putting my point at the origin.


This is an annoying problem. The issue is the 'magnetism' of the mouse to features which are already created. I believe there is a way to turn that effect off, or at least down, but I don't know exactly how. The workaround is to zoom in on the point you need to click on. When you zoom in far enough, you can click where you need to.


You may also find this helpful. When ADAMS is expecting a point input you can right click on an empty space on the grid. This will bring up an entry window where you can enter the point you desire. I find this way easier than trying to click a proper point using the coordinate window.
<<

F11Thao

Newbie
Newbie

Posts: 5

Joined: Mon Sep 12, 2011 7:58 pm

Unread post Tue Oct 18, 2011 10:17 pm

Re: Adams Assignment 4

On slide 27 where it says "file-export-table," Under type i'm not finding the table selection.
<<

TobyH

Newbie
Newbie

Posts: 39

Joined: Wed Sep 03, 2008 12:26 pm

Unread post Wed Oct 19, 2011 10:38 am

Re: Adams Assignment 4

F11Thao wrote:On slide 27 where it says "file-export-table," Under type i'm not finding the table selection.


You should do this step from the post-processing window. You can get there several different ways.
1. Press F8.
2. Click Review->Postprocessing...
3. Right-click on a plot, and select Transfer to Full Plot

From here, you should be able to follow the steps.

To return to the model, click the gear icon in the upper right hand corner.
<<

F11Matthew

Newbie
Newbie

Posts: 7

Joined: Mon Sep 12, 2011 7:58 pm

Unread post Wed Oct 19, 2011 3:02 pm

Re: Adams Assignment 4

I was working on the Adams Assignment and have an issue with my parts showing up. All of my joints, grounds, forces, etc are showing up, but the 3 actual parts are not. I was able to do everything through the step where it asked to rotate the link_3 out of the way (including verifying the model and running simulations). I was just going along without the visual, but I'm stuck there because I don't know where link_3 is in my model. I tried loading my woodcutter.bin on different computers, but had the same result. I even started completely over on a new computer once, but ran into the same problem.

Has anyone experienced this? Any ideas on how I can fix it?

Thanks,
-Matt

Return to ME451 Fall 2011: Kinematics and Dynamics of Machine Systems

Who is online

Users browsing this forum: No registered users and 1 guest

Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group.
Designed by ST Software.