I think the problems here are that DF assumes that you have a continuous force behind the bolt and that the Armor-metal is only paperthin so to say. Imagine a block of balistic gelatin, if you fire a bullet at it, it will bore in but somewhere down the way it will stop.
If the simulation assumes that the projectile has a continuous force behind it, it would go all the way through.
The second point of failure might be that the Armor is virtually paperthin in the simulation so that the projectile dosent dissipate enough energy (if at all) on the Armor since the thickness of the armor isnt taken into account.
I'm not sure I understand what you are saying, but I don't think it's correct. The reason bolts/arrows defeat plate armor is very simple. They are modeled as being very massive (about 1 kg), traveling at very high speed, and having a very small impact area. There is nothing about the force being applied continuously or the armor being very thin. As far as I can tell (from extensive testing, see the wiki article and previous thread I linked in the OP), the mechanics for armor are fine, more or less (good armor stops melee attacks most of the time). It's just that bolts and arrows have such enourmous momentum that they cannot be stopped.
Also bolts should be more deadly against Chainmail - if the bolt hit, normally it should rupture one or two rings of the mail thus removing any resistance from the armor. As it stands now i would think the [STRUCTURAL_ELASTICITY_CHAIN_ALL] token (that raises the "STRAIN_AT_YIELD" to 50000) is what makes the chainmail better at blocking arrows/bolts.
Agreed. The [STRUCTURAL_ELASTICITY_CHAIN_ALL] causes armor to convert incoming edged attacks to blunt attacks. This makes them slightly less deadly, but still quite devastating in the case of bolts/arrows. I believe that chainmail can fail to convert edged to blunt if the attack has extremely high momentum, but even bolts/arrows do not have enough momentum for this, and I can't remember if this is true.
isn't it kind of ridiculous that arrows get through steel plate by default anyway? i mean, at very close ranges maybe. but at long? the arrow will bleed off a ton of it's kinetic force at even medium ranges. no way a high quality steel armored dwarf should die to a +bone bolt+
just seems silly. if he gets hit in the throat or something maybe, but the chest? makes no sense.
By default, plate armor does not cover the neck or face (including the throat) or upper arms, and therefore would provide no protection to these areas even if it did normally stop bolts. Chainmail covers the neck and upper arms, but I don't think it covers the face.
Since this thread seems pretty well derailed anyway, what I would ideally like to see is modeling projectiles as hitting armor at some angle, with the momentum transferred (and hence damage and armor penetration) proportional to the cosine of the incident angle. This would mean that even crappy armor would have some chance to deflect projectiles if they hit at a glancing angle, while a perfectly true hit might penetrate even good armor. In the simplest case, you could just still assume each part is hit with likelihood proportional to its size, and treat all parts as spheres. Then the probability to hit at given angle is just a simple function which does not depend on body part size [Edit - just set the angle equal to asin(sqrt(Rand)), where Rand is a random number equally distributed between 0 and 1].
If you want to get even more realistic, you could allow shooters to target a given body part, and then calculate how close they come to hitting the center of this (based on skill, range etc). A miss would then have a chance of hitting other connected body parts, depending on their size and how far away they are from the targeted part. This would require somewhat more complicated calculations, but would be fun as you could realistically target body parts. Also, this would make legendary archers more deadly than novices, as they would be able to hit targets dead center.
I suspect Toady has something more detailed (if not this, then something else) in mind, which is why he's not bothered to fix the current system - he probably wants to do a major rewrite at some future time to make ranged attacks more realistic.