Learning Forum

[SC83]

Hi Sampat,

Thank you for your reaction.

I prefer to use Ansys static structural if possible. I have defined the mass of each arm with a point mass in its COG (see screenshot and blue dots in the top view) as I don't have a CAD model of the robot. Each mass is connected to the red colored surfaces (this is the interface between the robot and table) via a named selection. I want to simulatie the most extre condition, i.e. all arms in line rotating around the Z-axs. For this I have calculated the inertias of each arm as:

• I_arm_1_Z = I_arm_1_COG + m1.r1^2
• I_arm_2_Z = I_arm_1_COG + m2.r2^2
• I_arm_3_Z = I_arm_3_COG + m3.r3^2

I which r1, r2, r3 is the shortest disctance from each point mass to the Z-xis.

Or should I define for arm_2 and arm_3 the distance r2 and r3 wrt to their own rotation point, i.e. the joint_theta_2 and joint_theta_3?

When I support the table on its legs using frictionless support, I get the following error: An internal solution magnitude limit was exceeded. Please check your Environment for inappropriate load values or insufficient supports.  Please see the Troubleshooting section of the Help System for more information.

The model, currently without any accelerations - thus only gravitational forces, solves when I use fixed supports. Acutaully, there is friction between the legs of the table and the concrete floor (XY-plane). How can I add this to the model?