Originally posted by zraver
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the thicker plates are stronger than a laminated stack of thinner plates - with rolled hardened steel armor. the flexing is the start of failure, the thinner plates are defeated in detail, thick plates are stronger because they don't yeild as soon
spalling is a problem - they used splinter decks
Thus, with plates that follow the Linear Velocity Rule (and ignoring any other effects on the projectile due to the impact at the moment), using anything but single solid plates is clearly inferior to the single solid plate case, with the laminated case varying in its amount of reduction depending on the materials used (I usually spit the difference between the solid plate and the spaced plate cases when I calculate the laminated case, which works for most ductile plates that can form petals or plugs depending on the projectile nose shape and impact obliquity).
please see multiplate pdf
The US Navy after WWI, when determining the resistance of two laminated plates of the same type, simply assumed that the upper plate was reduced by 30% -- was only 70% as strong -- as to its thickness and then physically added to the complete thickness of the lower plate. For example, if the upper plate was 5" STS and the lower plate was 2" STS, the total effective deck thickness, regardless of the angle of impact or projectile type, was T(deck) = (0.7)(5) + 2 = 5.5" compared to 7" of total weight. This is quite a loss of strength for the weight, so there had better be a very good reason for not using a solid 7" plate.
1210. Summary of armor development.-It will be seen from the preceding review that each change in armor has added something, and that modern armor contains all the essentials of each successive product. First, for marine use, we had the simple wrought-iron armor, which was later developed into compound iron-steel armor. Then all-steel armor displaced the compound armor, and was, in turn, improved by the addition of nickel. Next we have a return to the hard face principle, but with homogeneous structure, in the application of Harveyizing. Finally we have the introduction of chromium and the development of decremental hardening as applied to both cemented and non-cemented plates.
http://www.eugeneleeslover.com/ARMOR-CHAPTER-XII-B.html
ARMOR-CHAPTER-XII-C
here is some data to illustrate - using the most modern battleship gun - the Alaska class 12"
note the lower velocity to defeat a thinner plate - the upper plate will be defeated, and the next plate will be attacked by the remaining velocity in the projectile - the thicker plate requires substantially more velocity to defeat
12” AP PROJECTILE MARK 18 (1,140 LB) (NEW IN REV. “J”):
These were for new ALASKA Class cruiser guns only. The remaining 12”-gunned battleships still used their old 12” Mk 15 MOD 6 “Midvale Unbreakable” (1916-vintage) shells, usually with new Mk 21 Base Detonating Fuzes.
In 500 projectile lots (except for initial lots, as specified by BuOrd).
3 projectiles for ballistic test from each lot;
1 projectile for fragmentation test from 1st lot only (unless further tests needed for some reason);
6 projectiles for flight test from 1st lot of new contract (range table verification) and 3 for flight test from each 5th lot thereafter (quality control).
Maximum Striking Velocity in any test was 2,300 ft/sec.
Ballistic Test Against Class “B” Armor @ 50° Obliquity:
Plate Thickness Striking Velocity (ft/sec)
4.0” 1,090
4.5” 1,190
5.0” 1,300 (1221 adjusted to 35 deg)
4.5” 1,190
5.0” 1,300 (1221 adjusted to 35 deg)
Ballistic Test Against Class “A” Armor @ 35° Obliquity:
Plate Thickness Striking Velocity (ft/sec)
9.0” 1,580
10.0” 1,720
11.0” 1,870
12.0” 2,010
13.0” 2,160
10.0” 1,720
11.0” 1,870
12.0” 2,010
13.0” 2,160
Modern laminated tank armor is a different animal - it is thicker and lighter by volume and addresses different threats than were faced by battleships
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