Implications of extremely strong composite materials?

Question

Ogre, a sci-fi tabletop wargame from 1977, used the development of an extraordinarily strong composite armor called 'biphase carbide' (BPC) as a technobabble justification for the widespread deployment of nuclear munitions in conventional warfare and a resurgence of tanks as the primary combatants of world powers. The intro to the game states that the armor is so light that even a ground-effect vehicle can carry several centimeters of protection, which is still enough to require 'the equivalent of a ton of TNT' to breach. Armored vehicles protected by layers of BPC are effectively invulnerable to anything short of a contact nuclear detonation.

It seems to me that widespread development of this material would have implications beyond being used simply as armor. While the game is deliberately vague about the material beyond stating that it's both very tough and very light, I'd think that a material that is so strong that it requires tactical nukes to breach while being lighter than steel should be useful for more than just armoring tanks. The focus of the game is on the AI-controlled supertanks, but I'm curious as to what the wider applications of this material would be. Lighter engines? More stable architecture? Should the implied materials science translate to civil applications, or do properties that make for good armor not necessarily have wider uses (eg, nobody makes buildings out of Chobham)? Or am I missing some obvious, world-changing application?

What would be the world-changing implications of widespread access to an extremely strong, but extremely light composite material?

Criteria and constraints for this material. I'm not a materials scientist so please bear with me.

• I've read that carbon fiber is currently about eight times more expensive than steel, and that price has thus far limited its adoption, so let's put the overall price for manufacturing (tooling, production costs, etc) at roughly four times that of steel. So cheaper than carbon fiber, and much more capable for the same roles (high strength, light weight), but still more expensive than steel.

• It's not particularly difficult to produce, or reliant on exotic materials. I'll say comparable to carbon fiber.

• It's not able to survive sitting on a nuke. It's strong enough to render conventional weapons ineffective, not invulnerable. Given that the Chobham armor of an M1 Abrams is speculated to be around five times more effective than a steel equivalent, I'll say that this material is fifty times tougher than steel per unit mass.

• Its density is a fifth that of steel, so a given volume of this material is ten times stronger than steel at a fifth the mass.

• Given the above, I know that this is pretty much an impossible wonder-material. Let's say it runs on the magic of handwavium and try to focus on the implications rather than the physical implausibility.

These are all ballpark figures, but I think may help narrow down the parameters. It's more expensive than steel, but far stronger despite less density. It has limits, especially cost-related, but it's physical capabilities are pretty high. So, what are the practical applications? Where will this technology change the world in immediately noticeable ways?

Answer 1

The purpose of armor is not to 'stop' a bullet, but to spread the kinetic force of a projectile (bullet, missile, knife, sword, shrapnel) into a non-lethal (preferably non-wounding). This might be by having a surface that cause the the energy to be redirected, such as a ricochet, or a sliding glancing blow. Others, like reactive armor have layers to absorb a direct hit and reduce the kinetic energy before it hits the next layer. However the first layer is reduced in effectiveness each time and a hit in the same spot will penetrate much deeper.

Now with a light substance that is almost impossible to penetrate, it really means it is EXTREMELY good at spreading out any kinetic energy applied to it, and maybe even able to channel/direct it. Because if I'm in a car that get's hit by a depleted uranium round from an Abrams tank, even if it doesn't breach the car, (especially with light armor) the impact will still rattle me around inside, possibly making a mess, like hitting a semi head on (a little hyperbole there!)

So most vehicles and other forms of personal transport would likely have this 'armor'. However just because a material can take a hit, does not mean it can actually support a large structure. It might crumble under the mass of a large building, so might only be a skin on the outside.

Now, taking into account the kinetic dispersal capabilities of this material, lots of sports might be made even more extreme. Why have a parachute, when you can put yourself in a sphere, and just 'bounce' after jumping from a plane, or off a mountain top? Why worry about a helmet for bike racing when a small bubble around the vehicle will save your life?

Answer 2

One thing which was not explored in the game was "how" the armour works so effectively. Some possible forms of armour absorb the energy of incoming blows by shattering or breaking, such as ceramic "strike plates" in body armour. The bullet hits the plate, and the energy is converted into creating a pile of fragments and dust inside the carrier. Unless you are exceptionally unlucky and get hit in the same place again, you survive the bullet strike by picking yourself off the ground and putting in a new plate.

Prior to the introduction of composite armour in modern tanks, many experiments along these lines were conducted, including ideas like putting panes of glass between two armour plates, with the glass shattering and taking the energy of the incoming round. I believe other materials tested were various types of salts as well (the salt also had the property of absorbing and dissipating much of the energy of things like HEAT rounds). As you can imagine, while things like this might work once, to properly protect a vehicle the armour would have to be in the form of "scales" so damaged pieces can be replaced. As well, much like dealing with Explosive Reactive Armour (ERA) bricks, multiple warheads on the same round (tandem warheads) are used to clear a path through the ERA so the main charge can get through the tank and kill the crew.

Going a different way, spider silk is about 5X stronger than steel by unit weight. Armour made of super fibres has been mentioned in other comments and answers, but because the strength is in tension, it has to be used in different ways than ordinary materials which are strong in compression.

The properties of these sorts of armours don't really lend themselves to other uses like structural support or engine blocks for vehicle motors, so while you can have an insanely light and strong material which might even need the use of nuclear firepower to breach, it might not have much of an effect on other industries.