Modeling Impact of one object on another (COSMOSWORKS)

Since you're not worried about what happens to the ball, don't model it.

Work backwards, of sorts. See how much it takes to cause a local failure in the bat. You'll have to figure out the contact area first, though.

Pick a "fast" number and model a drop test and see if that gives you a rough idea of contact area size. I'm not very familiar with the drop test functionality. Otherwise set it up as a contact analysis with the appropriate numbers.

Take advantage of the bat symmetry and refine your mesh only in/around the contact area to keep your solution times down.

Once you know your failure criteria for the bat you can work backwards to find out how fast the ball would've needed to go.

-Tony

Thanks for the feedback Tony. I really appreciate it.

However, your approach isn't really gonna work for me, as I miss-typed the original question. It *should* have read: "How much plastic deformation is done to a given surface (or subsurface) for a given projectile velocity?"

I think you've generated a viable approach, namely:

1) Find out what sort of contact area we're looking at from the baseball at X m/s contacting a perfectly hard surface or more reasonably, contacting a surface with some given Young's modulus and Poison's ratio (L-E material w/ no plastic deformation). I know this is possible via the COSMOS drop test (well the scenario is... I'll have to play with it to find the given contact area).

2) Define this area as the contact area for my baseball bat, taking appropriate steps to modify this contact area based on the curvature of the bat. Perform a static force analysis(?) given the force at impact... The thing is, the ball has only momentum, there's no force behind it, so I'm not exactly sure how to go about modeling the force distribution over my contact area.

Thoughts on this last part? Does anyone else have a different suggestion on how to go about modeling the damage done to the baseball bat?

Thanks again, Tony.

-Mike

This is not a CosmosWorks problem. It is an LS Dyna or Abaqus Explicit problem. It might also be tackled in Cosmos/M though not as elegantly.

One of the problems you face is that the problem is highly non-linear. It is also the type of problem that requires lots of very small time steps and a very refined mesh where plasticity occurs. Being non- linear (contact, friction, non-linear material behavior, geometric stiffening) it is path dependent. The material properties for the ball are likely to be a bit difficult to obtain. The information for the aluminum under high strain rates might be easier to find. So even if you could set it up it will take some time and trial and error to get it to run and give meaningful answers.

TOP

f = mv

Bob

Probably. This is a hard problem. You need to know the non-linear material properties of the bat and the ball at very high strain rates.Then you have to solve the problem with the very short time steps for a long time. One of my colleagues worked on something roughly similar for his Master's degree. He spent a lot of hours running analyses, running real tests on bats, comparing the results, tweaking the analyses, running tests...

Jerry Steiger