Yes they do interact between layers. I coat my armor with 500micron aluminum coat, the same material used in 77nm laser mirrors. It works really well against those extreme UV lasers.
Now, aluminum is a good mirror, but it cannot withstand that much heat. Aluminum alone would melt instantly under such laser. (As proven by stock designs) Graphene and 3d-graphene filler under that aluminum on the other hand have really high spec-heat and thermal conductivity. They absorb the heat from the aluminum layer and spread them all over the hall, making the aluminum last much longer.
Thank god, you've ended my paranoid delusions. So many screenshots of a railgun-riddled test target on my hard drive, as I pour over them, muttering
what does it meaaan!? It can be hard to analyze cause and effect sometimes because you've only the visual cues to work with, and those are limited for various practical reasons. The Mysterious Vanishing Crew Module is my biggest challenge, because visual evidence of spalling damage can be quite hard to spot sometimes. Then there's also shock and possible nuclear effects, which is also complicated by detonators being a little finicky - I've had shells from the stock nuclear cannon fail to detonate entirely. The shells hit the well-armored test target and the heavy, dense uranium core just punches right through for a kinetic kill.
From after-affects damage - with a single hole in the outer whipple shield, but glowing, heated armor only on the interior - it can be hard to tell if the missile physically penetrated the whipple shield before detonating and causing the backstop layer to spall and penetrate subsequent layers, or if the whole thing was an accidental nuclear EFP affect from the nose-cone armor (on my missile designs.)
Also, that heat-sink inner layer/aluminium outer layer design for anti-laser defense is
brilliant. I've been looking for a way to exploit the reflectiveness of aluminum for laser defense for a while now but couldn't find a good application. I'll be stealing that.
Mass also plays an important role.
Its illustrated pretty decently by my graphene armor scheme ( probably broken to begin with ).
Top to bottom.
2cm Si-gel.
1mm graphene
1m void
4mm graphene
5cm Al-foam.
2mm graphene.
Is generally quite sturdy.
However changing the 4mm graphene layer by a 4mm maraging steel layer led to less leakers.
The physical stats of maraging steel are worse ( very respectable overall ofcourse ) but I think the ~35x sectional density offered by the maraging steel does more to slow down projectiles in combination with the Al-foam and graphene backstop.
Mass does indeed matter. Consider the kinetic energy equation:
K = 1/2
mv2 (m = mass, v = velocity.) It's easy to see why railgun designs favor tiny masses at high velocities; the velocity has a much larger say in the eventual kinetic energy delivered. It's also much easier to accelerate lower-mass projectiles, because of inertia, the measure of a body's resistance to changes in velocity (a body at rest tends to stay at rest, etc.) The equation for inertia is simply
p = mv. In short, mass is a
lot more significant in inertia than it is in total kinetic energy. Thus your marang steel layer, with its 35x superior sectional density, has a lot more effective inertia, and thus negates more of the incoming projectile's inertia.
Very dense materiel is valued as armor for planetary applications because mass is usually less of a concern than volume, but in space the opposite holds true, which is why bulkier, lighter armor tends to be favored. I learned that the hard way when I realized my complex composite armor designs, using thin layers of high-grade materiel, were being outperformed by the simple stock ship armor designs, with a simple whipple shield and a thick layer of carbon or ceramic beneath it. When you take into account how that inertial relationship between railgun rounds and armor encourage them to
deflect very easily, however, dense armors become more attractive; since a round that skips off imparts a lot less kinetic energy (and thus does a lot less damage) to the armor, allowing it to outlast a mass-equivalent layer of amorphous carbon. You just need to angle your ship right, of course.
Apropos of nothing, but how do you tell when a crew module's been destroyed by radiation effects from nukes? Does the crew module actually vanish, as if it'd been hit with weapons fire normally?