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I want to do a test where I use composite materials to mimic impact damage on aircraft materials such as impact from hailstone while the aircraft is in flight.

I will cut out specimen sheets using a water jet cutter and they will have different size notches and then I will use a drop weight impact machine to create a hole in the material and assess any cracks or deformations etc.

Here is the design of the specimen sheets that I will cut out from the larger material sheet:

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My question is what are some good objectives that I can set for this experiment before the test is carried out.

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  • $\begingroup$ As some surfaces in flight do get a thin coating of ice, how will you allow for that? Also, some aircraft manufacturers are already using and repairing or replacing damaged panels. $\endgroup$
    – Solar Mike
    Oct 11, 2021 at 18:28
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    $\begingroup$ So, Charpy or Izod? $\endgroup$
    – Solar Mike
    Oct 11, 2021 at 19:30
  • $\begingroup$ @Solar Mike - Yep. You should explain those in an answer $\endgroup$
    – Pete W
    Oct 12, 2021 at 1:54

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Don't forget to maintain the temperature while carrying out the test. The material will behave differently when subjected to impacts on different temperatures.

Also, if the part you are experimenting on is the outside surface in contact with the air, then also don't forget to put on the necessary paint or any other surface coating that is originally used on it. This can also create a difference.

After cutting out the necessary specimens, make sure that the cuts are done gently and the cutted faces are smoothened enough to mimic the real life structure. The reason being after the cut out, the amount of pre-present cracks in the structure can increase and may make it more vulnerable to fracture than what can be expected in reality.

Since you are trying to model hail by dropping weights, you have to ensure that the weights has somewhat the same Elastic Modulus and rigidity as the hails. The reason being, if the weights are more rigid, then the cracks or even fracture can appear on the composite sample while it may not the case when hail of same weight is dropped on it. (Since in the situation of impact where drop weight is more rigid than a hail, all of the energy during impact will be taken by the composite sample).

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