Impact area of a steel ball on a surface

[J_chem]

Hey everyone.

I'm doing some impact testing, and I'm dropping a steel ball from different heights to test the strength of different materials.

How would I go about finding the impact area of the steel ball on the surface?

Thanks!

edit: also, does area matter? would I be better off rating these materials by force (F=ma) in which case contact area would be irrelevant...

or Pressure (P = F/A) in which case I would need to know the contact area of a steel ball on a surface?

Thanks again for any info

 

[pallidin]

It might be too advanced for what you are after/or can afford, but the following is from this source: http://cat.inist.fr/?aModele=afficheN&cpsidt=3665665

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The surface deformation which is caused by such an impact was measured by means of double-pulse holographic interferometry. Because of the small amplitude of the surface waves quasi-heterodyne holographic interferometry was required. The areas of initial wear of the materials can be recognized by the disturbed propagation of the surface waves.
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There might be simpler methods out there.

 

[timmay]

The contact area of a steel ball on a surface is best described by Hertzian contact mechanics. A good tribology or mechanics textbook will help with this, but essentially it depends on the radii, elastic modulus and Poisson's ratio of the two objects.

Please check my response to your other post for a better approach in your case; contact mechanics is a great way to analyse an impact such as this, but for your requirements you're probably after something a little more straightforward.

HTH,

Tim