×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*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.

# LMS Virtual Lab Kinematics / Inverse analysis Query

## LMS Virtual Lab Kinematics / Inverse analysis Query

(OP)
Dear Experts,

I am a newbie with regards LMS Vlab motion. I wish to model
a very simplified model of a suspension system defined by revolute and cylindrical joints.
I am interested in determining the resultant forces at the pin joints and the spring force due to an applied force at the wheel at a particular point in time.
After searching through the help file, my guess is that I need to do an inverse kinematics analysis in order to determine the reaction forces.
I have a few questions that I hope some of you might be able to provide answers.

1) I am interested the reactive forces at a particular point and position in time, e.g., in full bump. Is the inverse method the correct approach?

2) My understanding is that there needs to be accelerations in the models in order to calculate the forces from F=ma etc. I am not sure if i can achieve these forces if the suspension is fixed at a particular position etc.

3) A static analysis comes to mind but it appears that this method is only used to find equilibrium of the components prior to a subsequent dynamic analysis. So I am guess that is not the way to go??

Any information on the above queries will be greatly appreciated.
Kind Regards
Ed

### RE: LMS Virtual Lab Kinematics / Inverse analysis Query

1) don't know. The way we do it in ADAMS is to start with the suspension in a design condition and then move it by either applying  force or successive defined displacements (similar to IK) until we achieve the desired displacement of the wheel center.

2) Well you can't use statics like that unless you wish to apply D'Alembert forces to each mass.

3) If you want intertial forces then dynamics is the easy way to do it.

I'm astonished that there isn't a tutorial on this.

Incidentally from a practical perspective the inertial forces are very small compared with the static forces in a typical suspension in a typical dynamic event.

Cheers

Greg Locock

SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

#### 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.

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!