辐射4这次使用的是动态伤害减免，你的防御和对方攻击比较，防御超过对方攻击伤害后，防御效果(根据gengxiaoqi童鞋的提醒这里应该翻译成防御收益?)就极大下降。具体公式为50 potential weapon damage against 0 damage resistance (no ratio): ~50 damage is done (0% damage reduction).
60 potential weapon damage against 10 damage resistance (1/6 ratio): ~57 damage is done (~5% damage reduction).
20 potential weapon damage against 10 damage resistance (1/2 ratio): ~13 damage is done (~35% damage reduction).
20 potential weapon damage against 20 damage resistance (1/1 ratio): 10 damage is done (50% damage reduction).
30 potential weapon damage against 60 damage resistance (2/1 ratio): ~10 damage is done (~61% damage reduction).
25 potential weapon damage against 500 damage resistance (20/1 ratio, easily possible with power armor):~4 damage is done (~83% damage reduction).
Damage resistance returns in Fallout 4. However, the stat is no longer a 1-1 relationship with actual % damage reduced, as its value can be seen to be as high as 1000 on power armor.
Instead, the amount of damage reduction the player character gets out of the damage resistance is actually based on how much potential weapon damage is coming in; unlike previous games, net damage reduction is based on a ratio between the potential weapon damage done and the damage resistance, with diminishing returns for high damage resistance.
The amount of damage reduced by damage resistance climbs very quickly until damage resistance is about half of the potential weapon damage, after which diminishing returns means you get less and less damage reduction per point of damage resistance. Notably, if damage resistance is exactly equal to the potential weapon damage done, then exactly half of the damage is negated. In other words, if you have 50 ballistic damage resistance and are shot by an enemy doing 50 ballistic damage, then you'll receive 25 damage.
Note that the most important factor is the ratio between damage resistance and potential weapon damage.
The upshot is that unlike previous games, it is very hard to get to the point where e.g. enemy damage is reduced to the range ~20%. In addition, because the ratio between damage resistance and weapon damage is so important and because damage reduction grows very quickly at first for low values of the ratio, a higher damage resistance pays off mostly because it gives you better damage reduction against more-damaging attacks, not necessarily because it gives you better damage reduction against the same, weaker attack as before.
In other words, going from 20 to 40 damage resistance will only further reduce the damage done from a 10-damage shot by about ~12% (~61% to ~69% damage reduction), but it will dramatically boost your damage reduction against a 100-damage grenade by about 23% (~10% to ~30% damage reduction). Howeve, significant mitigation against such high damage is harder to achieve, since it is harder to get enough damage resistance to generate an appreciably high resistance-to-damage ratio. In otherwords, getting a 5-1 ratio is easy against a 20 damage shot, but very difficult (essentially limited to power armor) against a 100 damage grenade.
All final values below are adjusted by difficulty (for a player attacking an enemy):
x2.0 Very easy
x0.5 Very hard
Note that this is applied *after* the ratio and exponent are calculated, so damage resistance is applied on the base potential weapon damage, before difficulty-based multipliers are included in. This means that damage resistance is the same level of effectiveness (or ineffectiveness) on every difficulty level.
x2.0 Very easy
x0.5 Very hard