Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Deformation/fracture of material on impact

  1. Oct 4, 2011 #1
    I want to calculate the deformation of a plate of a material upon being struck by a mass moving along the plate's normal, and if the impact force is sufficient, if the plate will break or not. The given information can be assumed to be: mass, velocity, and contact area of the mass, and the thickness of the plate along with necessary material constants (e.g. Young's modulus).

    For the sake of an example, let's assume a 100 kg hammer moving at 10 [itex]\frac{m}{s}[/itex] with a contact area of 0.01 [itex]m^{2}[/itex] strikes a 0.1 m thick steel plate, of which Young's modulus is equal to 200 GPa.

    Some equations:



    Hooke's law

    To calculate [itex]\Delta{L}[/itex] I need force, which AFAIK is non-trivial to calculate. I found this equation


    Solving Hooke's law for F, substituting, and solving for [itex]\Delta{L}[/itex] yields the following


    This finds the deformation of the material using the given information, and with substituting the example the deformation is 0.0005m, which sounds reasonable for a 0.1m steel plate. However, I noticed that as the thickness of the plate increased, so did the deformation. I suppose this makes sense given the equation for strain, but seems counter-intuitive and leads me to wonder if I am doing this wrong. In addition, I have no idea where to start with the breaking point of the plate and how much force that requires.

    All help is appreciated.
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?