## General Mechanical

#### Convergence for results from drop test of plate on an element

• NAVID SALAM
Subscriber

Hi peteroznewman,

I would like to ask about the convergence study relating to a simple drop test on an shelled element. For the convergence study, I am analysing the declaration of the drop plate of different weights on a shelled component made of cardboard. I am having difficulty replicating the results and would like to know if there are any possible reasons for this deviation. We would like to converge the green line data points.

• peteroznewman
Subscriber

Please label the axes on the graph.  Define what HP and NUS mean.

What do you mean "having difficulty replicating the results"?

• NAVID SALAM
Subscriber

So NUS and HP are 2 teams that conducted the same test on an element body as shown above using a drop plate that falls at a velocity of 4.2 m/s on the element. The graph shown above shows the plot of a cushion curve which shows the deceleration vs psi of the drop plate. We are aiming to achieve HP's data for convergence but are not sure why the values are so different given we have matched their material properties of molded pulp product (something like cardboard). They are using the Radioss software with the James Cook model while I am using the Billinear Kinamatic model which also utilises the tangent modulus which i am not sure how to derive in this case. Do you have any suggestions have how to achieve convergence?

• NAVID SALAM
Subscriber

Our mesh element size is set to coarse with a set element size of 0.001 and with the drop plate set to a rigid body and the element set to a flexible structure.

• peteroznewman
Subscriber

I no longer see a legend on the plot showing which color is NUS and which is HP. Please add that back in.

You haven’t labeled the axes in the graph. You say “the plot of a cushion curve which shows the deceleration vs psi of the drop plate” and by convention when someone says y versus x the y axis is mentioned before the versus and the x comes after. However, I don’t know that you are following that lingustic convention.

Several things have the units of psi. What thing are you talking about?

It would be better if you just label the axes with names and units.

The title of the graph is also wrong. It’s not a Convergence Test, it is a Cushion Curve comparing two models.