I've been thinking a lot about making SR2 look more detailed and one of the things that makes it look unrealistic (compared to other games like KSP) is how plain the textures are. They're very useful and detailed but they lack scratches, bumps, burns...
I think the best approach (and kind of simple) would be a texture overlay with 4 layers (or 5 as I explain at the end):
- Heat damage
With this overlays 3 part attributes (heatDamage, collisionDamage, useDamage) that are directly correlated to the respective layer transparency and also to real consecuences like part failures over certain threshold.
Heat damage should increase if a part goes over certain temperature, and the higher the temperature the faster it increases. As it raises the part turns black/brownish (with noise, not just plain black) and it gets to the max opacity at about 2/3 the maximum suffered heat damage. When reaching the max heat damage threshold the part is destroyed.
Collision damage should increase with collisions over a certain speed. As in heat damage the stronger the collision the faster it increases. Max opacity should be at the same value than the max damage threshold.
Use damage should increase both with time (and even start in a non 0 value for parts outside of a fairing) and with low speed collisions and increase the scratch layer opacity, this alone shouldn't be able of reaching the max damage threshold but it should contribute, and the part failure point should be calculated with the 3 parameters combined.
A 5th layer may be useful for part temperature making the colors of the parts under 0 degrees white and the respective black body radiation color with glow to hot parts.
EDIT: Different fuselage styles could be added with different resistance, isolation, reliability... properties, changing price, available volume, fuel boiling...