Hello, I'm Hyungjin and I am studying for Simulation Sciences at RWTH Aachen University.

I'm working for fuel cell bipolar plates(BPPs) sheet metal forming structural analysis.

My model is structured with a tool(punch), metal sheet and die.

In my study, I assumed the tool to be a rigid body with a shell element and the sheet to be a continuum shell.

Furthermore, I used the mass scaling method to reduce the run time of the simulation.

I know that mass scaling is only suitable and available for sheet metal.

However, the rigid body of the tool was flown away when the tool and sheet were met.

So, I could consider that the mass of the rigid body was so light compared to the mass-scaled sheet.

After that, I applied scaled mass to the rigid body as well.

For example, 

Target increment time : 0.0001

Scaled ratio for mass : 68500 times 

Original mass of the punch : 300 g

Scaled mass of the punch : 19.75 ton

Finally, it didn't fly away and showed well-formed. 

To explain this situation, I need some scientific reason for this reason and calculation.

So, I want to ask if my thinking is correct and scientific reason if I'm correct. 

Thank you