Monorail Simulation and Contact Parameters

hoantuan123_12

I would like to simulate the operation of a machine traveling along a curved track, as shown in the picture. I would like to model the system using joints and motion, but I am not sure how to set it up because I believe that conventional joints may not be able to represent this type of track.

Could you please advise me on how to set up the joints and motion for this type of simulation?

Furthermore, regarding contact, I've came across the post "https://community.altair.com/discussion/62250/contact-models-in-altair-motionview".

I have some confusion regarding the contact parameters.

I understand that the parameters used to define Impacts and Contacts are based on Hertzian contact theory. I have also read several relevant materials indicating that the contact force can be calculated as:

F = (4/3) · E* · √R* · x^1.5
In which k = (4/3) · E* · √R*.
Based on this equation, I assumed that the unit of (k) should be N/mm(^{1.5}). However, in the Altair MotionView documentation, the unit of stiffness is stated as N/mm.

Therefore, I would like to clarify the following: if I want to calculate the contact stiffness based on Hertzian contact theory using the Young's modulus and radii of the two contacting bodies, how should I determine the appropriate stiffness value in MotionView?

Thank you very much!!!!

GTT Adam

Hi @hoantuan123_12,

There are several methods of constraining this machine to travel along a curved track.

• Motion Using Markers
• Advanced Joints
• Contacts

1. A Motion can be defined along with a curve to describe the target X and Y displacements of a body. This Motion is asserted to the body relative to a reference Marker. A planar joint can then be placed between the machine and the track to prevent movement in the Z axis. This method will essentially apply a force on the body to make it achieve those displacement targets.
2. To constrain the machine to the track, an Advanced Joint can be created. These types of joints can include point to curve (PTCV), curve to curve (CVCV), point to surface (PTSF), curve to surface (CVSF), surface to surface (SFSF), and point to deformable curve (PTdCV). For more on Advanced Joints, please refer to the following tutorial.
3. As for the IMPACT contact definition, it is defined as shown in the attached image and not the formula you have written. Other contact definitions exist, such as POISSON and VOLUME. If you want to use the material properties to define contact, then the VOLUME method may be suitable for you. Please refer to the link above for Contacts for more.

Hope this helps!

Adam Reid