Algorithm Summary

Kinetic Energy Algorithm

SURVIVE^TM flies a weapon into the target and calculates its penetration and trajectory through the structure until it can penetrate no more structure or the fuse detonates. It is possible to asses all manner of weapons from bullets to supersonic missiles.
Recent upgrades have allowed the effects of shaped charges to be modelled. This capability has been based on trials as shown below.

External & Internal Impulse Loading Algorithms

SURVIVE^TM checks the structure in the detonation compartment, hull, superstructure, deck, bulkhead, wall or window against blast impulse. The algorithm determines if failure occurs independent of any QSP calculation.

Blast Algorithms

The initial Quasi Static Pressure (QSP) is calculated using from the explosion using either a method based on TNT equivalence or the detonation and combustion energies of the actual explosive. The structure is checked against the dynamically applied blast generated QSP and failure determined.

Blast is propagated through failed structure, including doors and windows, into adjacent compartments either based on a relative fill time algorithm for each compartment or a method derived from vent area and the combustion chemistry.

Internal blast effects can result from a rupture of external structure caused by an external explosion. This is based on the size of breach caused by the explosion either through impulse or shock holing. The energy imparted through the breach area from the external impulse is estimated and an equivalent internal blast generated.

Blast spread for vessel without protection

Blast spread for vessel with protection


Fragmentation Algorithm

SURVIVE^TM treats fragmentation in a hybrid deterministic/probabilistic manner, tracing many thousands of statistically managed trajectories through the target, accounting for actual fragment penetration based on a number of rules for different fragment/target material and thickness combinations. The actual fragments produced by the weapon (determined either experimentally or theoretically) are then assigned to these trajectories to give the average number of each type of fragment that might be expected to hit or penetrate each equipment item or structural element.

Shock Algorithm

SURVIVE^TM uses the underwater UK MoD Shock Grade Curve Scheme for a particular ship. These allow prediction of the structural response at any point of the vessel, generating the motion that each item of equipment experiences. Items attached to the structure via shock mounts can have their above-mount response calculated by a damped-spring oscillator given data for the particular mount. Items not attached to the structure may be thrown into the air, which is particularly important for the prediction of human injury.

Whipping Algorithm

Whipping is the flexing of a ship along its longitudinal axis that is seen when a detonation occurs in the water nearby. SURVIVE^TM makes use of QinetiQ's expertise in spring-beam whipping models to establish the whipping response of a ship that can be expected from a given underwater explosion. In a similar way to the shock algorithm, this motion is used to establish the failure of any items of equipment unable to withstand the event.

Flooding Algorithm

SURVIVE^TM predicts the flooding likely to occur in each compartment as a result of holing of the hull or fire-fighting actions. The algorithm proceeds through time, transferring into and between compartments and calculates the new attitude of the ship at each step. The ship's stability can be found at defined intervals. The effects of counter flooding and pumping can also be estimated.

Residual Strength Algorithm

SURVIVE^TM has incorporated 2 other programs in order to assess residual strength. NS94D determines the ultimate strength at a particular section and PC009A determines the bending moments seen in a variety of loading conditions.

Fire Algorithm

A two-zone model capable of modeling whole ship fire scenarios can be used to rapidly simulate the spread of fire and smoke over a period of time. Fire loads can automatically be applied depending on compartment function, data having come from a survey of a Type 23 frigate. Custom fire loads can also be defined for special cases. The code models smoke generation and transport throughout the ship and to the external environment. It tracks plate temperature on both sides, conduction through the plates and allows different insulation schemes to be applied. Compartments that receive sufficient incident heat either via the plates or hot smoke can catch fire. Runtimes are short; a 2 hour fire scenario on a typical warship takes less than 30 seconds to process. This allows a wide variety of scenarios to be tested. The model responds dynamically to changes in the scenario - such as doors being opened and closed - and considers the effects of passive and active firefighting.

Crew Movements & Evacuation Algorithm

A model based upon experimental Royal Navy data for movement through a ship at different conditions can be used to assess the movement and evacuation of a ship's crew. The model can also be used to examine evacuation of buildings.