Learning Forum

[Soroush Jafari]

Hello.

The project involves impacting a tennis ball (made from hyperplastic rubber with internal pressure) against pre-tensioned tennis strings (made from polyester and nylon) at a maximum velocity of 265 km/h in a direction normal to the string bed. Observing the stress and deformation, the objective is to determine the thinnest possible string for the two materials under test.

 

I thought of conducting multiple steps from simple to more complicated toward the main project: 

 

1-Testing the solid ball(with Ansys predefined Explicit>Rubber-2 material) against a rigid plate : 

 

-body interaction: proximity-based frictionless

-mesh

 

 

-ball velocity: 7m/s

-plate displacements=0

 

-analysis setting: 

end time: 2e-2

automatic mass scaling=no

max no of cycles: 1e7

 

RESULT:

The ball bounced back when hitting the plate

  

 

Issue 1: when we increase the speed(50m/s), some ball elements penetrate and get stuck into the plate, preventing the ball from rebounding. we tried refining the mesh but the issue insisted.

 

issue 2: we acquire the tennis ball and polyester string material properties(stress-strain curve) but assigning it to them gives us an error.

 

  

 

 

error: 

"You have specified result time(or frequency) = 0.00226447262556333 for a result file which has maximum time(or frequency) = 4.19585521740373e-05.  If you specify 0(ZERO), the solution for the final time will be displayed."

issue 3: Regarding applying a pretension force on the string in the main analysis, we have difficulty effectively applying it.

 

I attached the verification(Ball_impacting_plate), the main project file and the materials stress-strain data. Materials are also already added to the Engineering Data of the verification file.

Main Project

Ball Plate

polyester stress-strain curve

Rubber Stress-strain curve

 

I appreciate your help.

Thank you

[Kate Bishop]

You can try to refine the mesh, adjust contact settings, and use a smaller time step for high velocity. Besides, double-check material properties and output request frequency. Apply pre-stress in a separate analysis or use pre-displacement in the main analysis. Wordle Unlimited

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[fobofo8381]

You can try to refine the mesh, adjust contact settings, and use a smaller time step for high velocity. yuzde