Reinforce Field

So you have a deflector shield that stops incoming objects or propagating fields. It's cool. You know what we really need to stop from moving too much? Parts of armor plates and loaded girders. Or, if you prefer, electric fields of electron shells and nuclei of respective atoms. So if it can work inside condensed matter, it could (and should) be used to make materials more resilient.

Some settings have "structural integrity fields" reinforcing the spaceship's existing frame. As an extreme variant, few settings have extra-extra-large constructions (including spaceships) that are explicitly stated to be physically possible only due to force fields keeping them from being crushed or torn apart. Size matters, but scaling things up is not cheap. Spaceships can be free from the burden of gravity, but unlike loose asteroids and orbital stations they have to move, and any noticeable acceleration of a great mass involves great forces, and turning—even inertial—gives G-force increasing proportionally to radius. Of course, strengthening effects have lots of other uses, up to and including reinforcing frail melee weapons to make them both sharp and resilient.

See also Deflector Shields, Containment Field and Inertial Dampening. An opposite effect is Disintegrator Ray.

Giant Craft

 * Full Metal Panic! once had a 40 meter tall Humongous Mecha, in which the fact that a mecha of it's size normally shouldn't be able to support its own weight was a major plot point. The only reason it even manages to stand up is due to it being supported by a Reinforce field. Sure enough, when it was damaged, the entire thing collapses on itself.
 * Galactic Civilizations 2: Massive-class ships. A couple of research projects tinker with the "Q-field" to increase the resilience of your ships.
 * Master of Orion 2: Doom Star class ships are stated to require these to be feasible.
 * Tensor fields in Star Wars.
 * One might argue that, from their description in the Star Wars technical manuals for the extended universe, that Particle Shields are a type of reinforcement field that makes armor more resilient against physical impact. (Ray Shields, by contrast, are most definitely Deflector Shields.)
 * In Mikhail Akhmanov's Invasion, a massive alien starship arrives to the Solar System and proceeds to Curb Stomp Battle a large chunk of the Earth Space Navy (to be fair, humans have just begun to explore space at this point and lack FTL). When the ship lands in the Antarctic to use melted ice as raw materials for repairs, a different alien teleports on-board and gives the protagonist a device that will destroy the ship's bio-computer. Apparently, the ship is too massive to be able to support itself, and it's being reinforced with force fields that are controlled by the computer. As soon as the computer dies, the ship collapses on itself like a tin can, killing everyone onboard. Apparently, the aliens have never heard of backup systems. The Reinforce Field has not been mentioned in later novels.

Miscellaneous

 * The almighty Peter F. Hamilton has, in his The Nights Dawn Trilogy, 2 things like this. The first is the Molecular Binding Force Generator, which reinforces materials several times over their normal strength (it might be only with some specially-made materials, but it's not clarified), and the Valency Generator, which is cleverly used in an airbag-like safety mechanism: in a collision, the vehicle is flooded with a gel or foam-like substance, and then the valency generator kicks in, making the substance rigid, absorbing the momentum of the passenger. Yeah, you need to be cut out of it, but still, you're safe.
 * Star Trek has lots of shields and force fields. On Star Trek: Enterprise, we even get to watch these get invented. Later ships have a "structural integrity" system, to or from which one can divert power. The abundance of Tim Taylor Technology coupled with the availability of force fields has led some to theorize that, in fact, all Federation technology is held together by tiny force fields.
 * Mentioned in the Quentyn Quinn, Space Ranger Take That aimed at Star Trek, among many other aspects of the Federation that get the treatment.
 * The Structural Integrity Field [TM] first received that name on Star Trek: The Next Generation. Presumably, the "polarized hull plating" of Star Trek: Enterprise was the forerunner to TNG's structural integrity field.
 * In Dungeons and Dragons magic items are more resilient than their mundane prototypes, and all artifacts are almost indestructible (much like the One Ring). There were even enchantments specifically making important things much less fragile.
 * "Glassteel" is the glass enchanted to be as strong as steel. And it's still as non-conductive, corrosion-resistant, and light as glass. Thus, the natural choice for armor of various flying warriors, whether Aarakocra, Avariel or Nimbral (Forgotten Realms) pegasi cavalry.
 * Player’s Option: Spells & Magic has spell "Greater Sign of Sealing" that locks a portal or item and gives it a hefty bonus to all saving throws and resistance to damage equal to caster's level (for 6-level spell it's from 11 and up). And AD&D2 and PO are not very generous with damage bonuses, so this DR is rather formidable in itself, especially if you don't want to use overkill spells that will blast everything around it into ashes too.
 * Forgotten Realms being a well-detailed setting, there are several other permanent spells for this specific purpose (Nulatoe's Ninemen for organic remnants, Veladar's Vambrace and Holy Might for other things). Merald's Meld "glues" parts together so that instead of breaking the whole only fall to components, Crown Meld doesn't enhance in itself, but "borrows" the best resistance of all component materials (enchanted items save to negate damage, as steel vs. impacts + as ceramics vs. fire, acid and electricity = Nigh Invulnerable).
 * The Epic Level Handbook in D&D3E contains an adventure which includes a wizard tower with walls made of two thick layers of obsidian with a thin forcefield in-between.
 * Shiki's glasses in Tsukihime are indestructible, period. The reason for this is that they block out his Evil Eye effects that allow him to destroy anything, period. Makes sense to have an indestructible Power Limiter on an omni-destructive ability, doesn't it?
 * A variant of this is in Fate/stay night. Reinforcement is one of the most basic forms of magic, and can be described as concentrating an objects traits. For instance, reinforcing a wooden sword makes it temporarily harder, sharper, and more resilient, reinforcing a body makes it Made of Iron and minor Super Strength, reinforcing eyes gives you eagle vision etc.
 * Every so often (especially in the guidebooks), a structural integrity field is used to explain why Iron Man can withstand a punch from the Hulk.
 * One sample explanation for the cosmic armor in GURPS: Spaceships is that it increases the binding energy between atoms.
 * Minds in Iain Banks' The Culture series don't even bother to reinforce normal matter, their entire structure is made of shaped force fields.
 * In Magic: The Gathering's "Scars of Mirrodin" expansion, the flavor text for Tumble Magnet suggests and inverts this trope: "Magnetic devices that keep massive golems and structures standing can also be used for the opposite purpose."
 * Earlier in Mirrodin there is the Darksteel, magical metal that is plain Indestructible. Things made of Darksteel has eerie light balls orbiting them, be they weapons, golems, or metal fortresses.