Structural integrity
Structural integrity was an engineering term used to describe something's natural or artificial ability to withstand outside physical forces, such as the hull of a starship. Structural integrity power was one way to assist with maintaining structural integrity.

While standard architecture uses supports and bulkheads to make constructs stronger or more durable, the fantastic  presented by combat, warp fields and spatial phenomena have caused engineers in the Federation and other spacefaring species to use force fields to hold the shape of a construction together. This was referred to as a structural integrity field.

In 2063, Data informed Captain Jean-Luc Picard that the structural integrity of the Phoenix was intact, even after the attack by the Borg sphere. Later, Geordi La Forge informed Zefram Cochrane that the structural integrity of the Phoenix was holding as the ship prepared to go to warp speed. ()

In 2151, Malcolm Reed and  repolarized the gravity plating of  to absorb the plasma recoil, caused by the newly integrated phase cannons, and shunt the energy to structural integrity. ()

In 2152, Travis Mayweather polarized the hull plating of Enterprise to strengthen the structural integrity before entering a neutronic wavefront. ()

The stress of a Romulan tractor beam caused sub-microscopic deformations in the structural integrity, especially the nose section and aft thrusters of the Type 15 shuttlepod Onizuka. ()

In 2369, Geordi La Forge planned to run a structural integrity scan of a conduit located in cargo bay 4 aboard the , but had to report to sickbay due to an issue with his VISOR. Data stated that he would run the scan instead, and had just started it when La Forge returned from sickbay, having been abducted without his knowledge by the solanogen-based lifeforms. ()

The same year the tractor beam of Deep Space 9 was able to stabilize the structural integrity of Tosk's ship. ()

In 2372, the 's structural integrity began to weaken after the shuttlecraft  went to transwarp and Voyager was unable to sustain warp 9.97 to capture it. ()

In 2374, during an encounter with a group of Omega molecules, Captain Kathryn Janeway ordered Chakotay to increase the structural integrity of a shuttlecraft in order to properly dispose of the molecules. ()

Failures of structural integrity

Hull stress 
Hull stress was a condition where, on a starship, space station or other installation, the hull encounters a form of stress. This could be caused from a form of pressure pulling against the ship, such as an object pulling against another. Hull stress, if critical enough, can lead to a buckling and eventually a hull breach.

When the  was caught in a quantum singularity in 2371, they found what they thought to be another ship caught further in the singularity. When Voyager attempted to lock on the ship with a tractor beam, the singularity started to pull the ship in. The ship was put into full reverse impulse, but with the tractor beam still on, this caused hull stress. ()

Microfractures 
Microfractures were microscopic cracks in the hull of a starship that, while invisible in the naked eye, could widen over time if something aggravated it and cause more drastic problems. The term also has a medical context.

The structural integrity of a material was diminished when microfractures were present. This could have dangerous, even deadly, consequences when the deterioration occurred in a ship's hull or other structure which provided containment, shelter, or life support, or in a living tissue. However, under certain conditions, a limited amount of microfracturing could be tolerable. ()

Some microfractures could be sealed by an engineering team, yielding a temporary or permanent repair. Other microfractures required the rebuilding or replacement of the structure. (; )

Causes
While approaching a second Sphere in the Expanse, Enterprise suffered microfractures on its hull due to gravitational anomalies ()

Microfractures could result from torsional stress damage or from weakening of stress-bearing material by some environmental condition. ()

The 's displacement wave which transported the  from the Badlands to the Delta Quadrant caused several microfractures to the ship's warp core. ()

Duranium alloys could be vulnerable to certain silicon-based parasites, which consumed the material. The weakened duranium could microfracture under stresses that normally would be within tolerances. ()

Theta radiation could degrade hull materials, yielding microfractures when stress levels were normal. ()

Gravimetric distortions created violent stresses that caused damage beginning with microfractures and ultimately yielding total structural failures, if not mitigated by escaping the distortion. (; )

Proton bursts caused great stress on a ship's hull, leading to over 630 microfractures. ()

High warp core pressure, near critical levels, could microfracture the dilithium matrix. ()

Microfractures could occur in warp nacelles, accumulating over time until maintenance became necessary. ()

A physical injury to a living being could damage the skeleton with microfractures. ()

Effects
Microfractures left un-repaired could widen to become full hull breaches. ()

EPS conduits could experience  drains if microfractures were present as the energy escaped from damaged conduits. ()

In 2369, the shuttlecraft Fermi was destroyed when an energy anomaly caused molecular deterioration and microfractures in the bulkhead. () A plasma conduit aboard the Tyrus VIIA station exploded, due to an undetected microfracture. ()

In 2375, Varro saboteurs aboard the Varro generational ship destabilized the warp reaction when their synthetic parasites caused microfractures. ()

Prevention
A vessel's structural integrity field could provide enough reinforcement to prevent microfractures or to preserve integrity when microfractures were already present. ()

Twenty-second century hull plating was some protection against hull stresses which could cause microfractures, as was trellium. ()

Compensation for a microfractured dilithium matrix was possible, in order to avoid warp engine problems. ()

A metallurgical scan was one way to discover microfractures. ()

Hull breach 

The term hull breach or hull rupture refers to the failure of structural integrity where the shell surrounding said pressurized environment breaks, stresses or develops a gap for any reason. In space-faring vessels, this is usually catastrophic. The pressure of a contained atmosphere forcing its way outward in an explosive decompression can cause further damage to the area, and also have the added effect of endangering or killing any lifeform present. Since the pressure is internally generated, Lieutenant Commander Data stated to Commander William T. Riker in 2364 that being "blown out" was probably a more accurate term than being "sucked out." (; )

Most hull breach dangers are from pressurized material contained within a vacuum, or lower pressure, environment. However, it is just as possible that the pressurized vessel could be surrounded by high pressure gases or even liquid, causing an implosion, forcing the surrounding environment into a vessel. The  experienced such breaches in 2372 when trapped in the atmosphere of a gas giant. ()

Vessels of spacefaring civilizations and cultures, such as the Federation Starfleet, protect themselves against the extreme stresses of both pressure and vacuum, as well as the added dangers of impacts, warp drive stress, weapon damage, energy phenomena and anomalies, by implementing a structural integrity field. This force field is designed to occupy the same space as the ship's hull, effectively giving them hundreds of times the ability to hold its shape. Force fields are also used to automatically contain the atmosphere, and repel external forces, should the hull be breached. (; ; ) Prior to the development of these technologies, emergency bulkheads and polarized hull plating were used to contain and avoid breaches ()

Notable hull breaches 
  sank due to a hull breach struck by an iceberg.
  cargo module 8 caused by Matthew Ryan while the away team from Enterprise was trapped inside in 2151. ()
's C-deck, caused by two Vulcan patrol ships and a  ship. ()
Enterprise NX-01's G-deck, in the Battle of Andoria. ()
Enterprise NX-01 suffered multiple haul breaches when they struck a cloaked Romulan Tricobalt Mine in their minefield in a system that was annexed by the Romulan Star Empire. One of the mines latched itself onto the hull and Archer and Reed had to go out and defuse it finally jettisoning the mine into space and detonating it while using shuttle pod doors as shields to protect them from the blast. ()
 suffered multiple hull breaches and damage to the warp core and dilithium crystal converter assembly after being attacked by  which was commandeered by Khan and his Augment crew. ()
's Saucer section, which was hit by a torpedo from General 's Bird of Prey. ()
's Engineering section, which was presumed to have killed James T. Kirk. ()
In 2365 the  experienced hull breaches and loss of atmosphere and structural integrity from a cutting beam after Q sent the Enterprise into the path of a Borg cube. ()
A year later in 2366 the Borg invaded the , kidnapped Captain Picard, and forced him to destroy the Federation Fleet at Wolf 359. During the battle several Federation ships were damaged or destroyed including . The Enterprise herself was also damaged during the climax of the battle and had to be sent to McKinley Station for emergency repairs and upgrades. 
 In 2369 Deep Space 9 had several hull breaches and fractures in their bulkheads caused by the graviton pulses of the embryonic lifeform. ()
 In 2370 Deep Space 9 had a hull breach on Section 14. ()
One of Deep Space 9's upper pylons was destroyed by a Jem'Hadar strike team. ()
In both Years of Hell, several breaches on the  due to the Krenim. In the second version of this year, Voyagers Deck 5 suffered a breach, caused by damage from Krenim weapons fire. ()
In 2371, Voyagers hull breached when a 's grappler was torn off. The breached section quickly exploded afterward. ()
In 2371 during the Battle of Veridian III, the  suffered hull breaches on decks 31 through 35. ()
's bridge, caused by disruptor damage from the Scimitar; as well as several decks' worth when the Enterprise rammed the Scimitar. ()
In 2380, the  and  were breached by terraforming emulsion. ()

Hull temperature 
The hull temperature was the temperature experienced on a starship's hull when exposed to extreme . It was one of many factors taken into account for establishing starship design parameters. 

As  approached a hypergiant in 2154, the ship could only get as close as about twenty thousand kilometers out, before the hull temperature approached 1,100 s. During this mission, they encountered a Vissian starship, which had a hull constructed with trinesium and allowed it to withstand temperatures up to 18,000°. ()

As the  pursued a Denevan ship heading into the Denevan sun in 2267, Spock began noting the ship's outer hull temperature on approach beginning at 480°, before announcing the temperature was at 1,000° and rising, and that they were getting too close. ()

The following year, when the Enterprise was hijacked by the Kelvans and forced to travel across the galactic barrier, as they made contact with the object, Montgomery Scott warned that the outside hull temperatures had risen to over 2,000°. ()

In 2364, Geordi La Forge attempted to cajole a cloaked and hostile Echo Papa 607 unit out of hiding, while it and the  were in orbit of the planet Minos, by entering the ship's battle section into the planet's atmosphere. In doing so, Lian T'Su initially warned that the hull temperature was at 1000° and rising, prompting La Forge to request emergency power to the deflectors. When the hull temperature reached 2,500°, Worf warned that the ship's deflectors were nearing overload. After the hull temperature reached 3,000°, Worf warned that they were about to lose number four deflector, and at 3,300°, the same deflector became inoperative. ()

Later that year, the Enterprise responded to a distress call from the Ornaran freighter , which had lost helm control and began losing orbit. Upon arrival, Worf observed that the freighter's hull temperature was passing 3,000°, some moments later, the freighter began to disintegrate as its' hull temperature approached critical. ()

In Doctor Beverly Crusher's attempt to shake a pursuing Borg type 03 by hiding by a nearby sun, she requested that Taitt and Barnaby bring the metaphasic shielding program online so that they could enter the sun's corona. Prior to initializing the program, the Enterprises hull temperature was at 12,000°, and the radiation level was near 10,000 rads. After activating the program, the ship's hull temperature dropped to a more tolerable 7,000°. ()

When 's outer hull temperature reached 9,000°, the ship's hull began to buckle. ()

External link 
 
Physics