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What is explosive damage?
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Kel hound
The Scope
Gallente Federation
#21 - 2013-09-23 23:59:05 UTC
Savira Terrant wrote:
I cannot seem to be able to wrap my head around what impulse shock exactly is (and why it works in space)Question


taken from Atomic Rocket conventional weapons.



Quote:
First, consider a uniform slab of material subject to uniform irradiation sufficient to cause an impulsive shock. A thin layer will be vaporized and a planar shock will propagate into the material. Assuming that the shock is not too intense (i.e., not enough heat is dumped into the slab to vaporize or melt it) there will be no material damage because of the planar symmetry. However, as the shock reaches the back side of the slab, it will be reflected. This will set up stresses on the rear surface, which tends to cause pieces of the rear surface to break off and fly away at velocities close to the shock wave velocity (somewhat reduced, of course, due to the binding energy of all those chemical bonds you need to break in order to spall off that piece). This spallation can cause significant problems to objects that don't have anything separating them from the hull. Modern combat vehicles take pains to protect against spallation for just this reason (using an inner layer of Kevlar or some such).

Now, if the material or irradiance is non-uniform, there will be stresses set up inside the hull material. If these exceed the strength of the material, the hull will deform or crack. This can cause crumpling, rupturing, denting (really big dents), or shattering depending on the material and the shock intensity.



Imagine a hypothetical spaceship is subjected to a hit, or near hit by a nuclear missile. Basically, if the atomic explosion is not close enough, or powerful enough, to instantly vaporise our imagined ship hull you should see some interesting things. First, a thin layer is vaporised from the hull. If you've ever watch footage from nuclear tests then you should be familiar with -this image-. On our spaceship this initial damage should be superficial, but intense enough to cause a shock wave to propagate through our armor and hull. Because our ships armor and hull is not perfectly uniform this creates stresses throughout the material. When the shockwave hits the back of the armor these stresses can cause fragments to break off at roughly the same speed as the shock wave is traveling through the hull - this is known as spallation. This effect can happen as many times as the shockwave still has energy - which will be dependant on how much energy was imparted to the ships hull by our impact or near impact from the atomic device.



Again, I feel the trick to understanding the 4 damage "types" is not to analyse their physics but rather their effect on our hypothetical ship. While this nuclear device is giving off electromagnetic and thermal radiation, the -way- in which it is affecting our ships hull determines the damage type.
Savira Terrant
Native Freshfood
Minmatar Republic
#22 - 2013-09-24 23:31:34 UTC
Well, a tradional shockwave would apply damage by putting strain (thus deformation) on the structure as a whole by resulting in internal elastic stress. IF the deformation (read kinetic impulse on a given point) is big enough spallation will occur on the backside of the fluid at the point of impact.

That being said, if the explosion takes place right on top of a ships hull (basicly while touching it), I can understand that the resulting pressure changes within the material can cause spallation. Btw. the effect would be no different then that of a bullet defeating the plate or not, thus however I reduce spalation effects on my armor, it will be protected to kinetic and "explosive" damage types in the regard of "how it is applied". Same with hydrodynamic flow, which is in part caused by supersonic shockwaves. Likewise with the vaporization, which occurs due to heat and EM waves.

On the site you linked, they were talking about how this effect is even possible with a detonation in empty space, of up to a kilometer away from the ship (although resulting in lower energy at impact due to the inverse square law).
My point is: Where does impulse shock come from (which would supposedly be the effect that causes damage akin to a traditional atmospheric shockwave)? Because if there is no fluid to pass on an impulse, than the energy released would not be able to dissipate with kinetic impulse so will as EM waves instead.

Well, I can see a difference of the "how it's applied" for EM and heat damage: heat could be induced by EM, but also a chemical exothermic reaction with a oxidsubstrate, thus not depending on an atmosphere.

So how can I understand what impulsive shock is?

.
Veikitamo Gesakaarin
Doomheim
#23 - 2013-09-25 00:56:37 UTC
The different damage types could also just be an abstraction since we don't know the exact composition of the materials used for armor, the technology behind shields, or the design of the weaponry used to defeat them. However if it's assumed that the defensive technology in Eve is at such a level that it makes, "One shot, one kill" penetrations practically impossible then the spaceship weaponry is designed to continuously apply damage to another ship until it either its shield or armor reaches points of significant failure.

Taken just for armor, the materiel science behind it might be so advanced that its extremely difficult to penetrate. The different damage types describe in an abstract form how different weapons systems interact and seek to induce either stress, failure, or continued ablation to that armor.

A laser seeks to ablate the armor off the hull by applying direct energy to the material.
A blaster seeks to ablate the armor off the hull by its initial impact and heat from its plasma
A railgun seeks to ablate the armor by its initial impact and the creation of heat from kinetic energy
An explosive round seeks to ablate the armor by causing deformation, stress and shock in the materiel

The em/thermal/kinetic/explosive damage types might just be the shorthand of saying, "The majority of armor materials in Eve spaceships are more susceptible to being ablated off the hull by continued deformation, stress and shock than by directed energy." That, or they're not intended be taken at face value, but as said, the abstraction for different material/weapon interactions which saves the servers from having to make complicated physics calculations everytime the F1 key is pushed.

Even the different projectile rounds which do explosive damage only have it as a component. This probably describes the different effects, in an abstract form, of what the round actually does and how it is designed. A Fusion round does kinetic damage as a function of its initial impact and then explosive as a form of concussive/shock effect against the armor plate designed to cause local area buckling, deformation and stress. A Phased Plasma round does kinetic damage as a function of its initial impact, but then only thermal (no explosive) as the plasma is released against the hull plate.

This abstraction of damage types might also be why explosive damage is less effective against shields. Because it's describing the effects of specific types of rounds designed to transfer concussive effects which are highly effective against dense materials like armor plating, but less so against whatever sort of energy/particle field shields are made out of.

That's about the best I can offer beyond, "Minmatar space magic" because without having the specifics of the warhead design or the materials used for armor in Eve I would say it's impossible to describe the exact mechanisms or effects involved beyond the abstract system given in the game.

Kurilaivonen|Concern
Kel hound
The Scope
Gallente Federation
#24 - 2013-09-25 01:07:01 UTC
Savira Terrant wrote:
...
On the site you linked, they were talking about how this effect is even possible with a detonation in empty space, of up to a kilometer away from the ship (although resulting in lower energy at impact due to the inverse square law).
My point is: Where does impulse shock come from (which would supposedly be the effect that causes damage akin to a traditional atmospheric shockwave)? Because if there is no fluid to pass on an impulse, than the energy released would not be able to dissipate with kinetic impulse so will as EM waves instead.

...

So how can I understand what impulsive shock is?



The impulse shock is caused (as far as I can tell) by a rapid, almost instantaneous change in temperature on the ships hull and/or armor. In essence, the radiated thermal energy from the bomb is transmuted into raw kinetic energy as it comes into contact with the metallic hull as dictated by inverse square law. No medium is necessary.
Isis Dea
Society of Adrift Hope
#25 - 2013-09-25 06:04:41 UTC
EM = EM (present day concept)
Explosive = HEAT (present day concept)
Kinetic = Sabot (present day concept)
Thermal = Incendiary (present day concept)

Think similar fundamentals as per type of weapon being used within EVE and you won't be far off.

Example A: Kinetic missile discards sabot tails and drives a silver needle into the hull of the target.

Example B: Thermal missile slams into hull, proceeding to eat into it (much like a plasma conceptual warhead in typical sci-fi).


Be wild in imagination, no weapon/ammo maker makes everything the same, and we simply translate the post effects of the ammo into one of the four types of damage. You can also use the descriptions of the ammo to help with your imagination.

"Missing constantly? Maybe where you bought your ammo is to blame..."

More Character Customization :: Especially compared to what we had in 2003...
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