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FSI or what?

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Old   October 19, 2012, 10:17
Default FSI or what?
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I have a problem in hand to model a flying bullet impacting a plate. Velocity and weight of bullet is known. This thing can be modeled by using Fluent/Mechanical APDL or not? Is it a kind of FSI problem or what? Thanks
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Old   October 19, 2012, 13:02
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If any body know something then kindly comment please........
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Old   October 19, 2012, 22:02
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My first response would be no, at least not in the classical FSI sense. Once the bullet impacts the plate the aerodynamics are essentially inconsequential to (and thus decoupled from) the deformation of the bullet, unless you are considering the bullet fragmenting and it is desired to track the fragments. You could use CFD to determine the initial state of the bullet immediately prior to impact, but the impact event and the resulting deformation would seem to depend very little (at best ) on the aerodynamics, apart from the aforementioned particle tracking. At least that's my semi-informed opinion.
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Old   October 20, 2012, 03:15
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Quote:
Originally Posted by agd View Post
My first response would be no, at least not in the classical FSI sense. Once the bullet impacts the plate the aerodynamics are essentially inconsequential to (and thus decoupled from) the deformation of the bullet, unless you are considering the bullet fragmenting and it is desired to track the fragments. You could use CFD to determine the initial state of the bullet immediately prior to impact, but the impact event and the resulting deformation would seem to depend very little (at best ) on the aerodynamics, apart from the aforementioned particle tracking. At least that's my semi-informed opinion.
Thanks for your response. You mean to say that I should calculate trust force of bullet from cfd and then use this force to calculate deformations in Mechanical APDL?
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Old   October 20, 2012, 12:58
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If I were doing the simulation, I would use CFD to compute the flight of the bullet up to the moment of impact. At that moment you have the state of the bullet, i.e. position, velocity, acceleration. These would serve as inputs to the solid mechanics solver. I don't have experience with your particular software, however. Just lots of time spent doing coupled CFD-6DOF analyses.
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Old   October 23, 2012, 19:02
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it all depends on what you need and how much in detail you want to go.

assuming that you are interested on what happens on the plate, i would go for a first calculation using a nonlinear dynamic FEA analysis (i think that mechanical can do them) using a time varing impact force as a boundary condition.

if you need more accurate results, you'll probably need an explicit FEA software. LS-dyna comes to mind but there are more.

but crash simulations are not easy, and they take many years of study and tests to master.

i don't think thet cfd is the answer for your problem, unless you want to study something you havn't told (shaped chrges, maybe?)
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Old   October 24, 2012, 11:32
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it all depends on what you need and how much in detail you want to go.

assuming that you are interested on what happens on the plate, i would go for a first calculation using a nonlinear dynamic FEA analysis (i think that mechanical can do them) using a time varing impact force as a boundary condition.

if you need more accurate results, you'll probably need an explicit FEA software. LS-dyna comes to mind but there are more.

but crash simulations are not easy, and they take many years of study and tests to master.

i don't think thet cfd is the answer for your problem, unless you want to study something you havn't told (shaped chrges, maybe?)
Lately I learned that this problem can be solved using LS Dyna or Auto Dyne.....currently working on Auto Dyne
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