Feature 5
Numerical and visual results are outputted SURVIVE caters for both outcomes, loss of strength occurs.
in user-friendly forms. using a number of rules to calculate shock SURVIVE uses a two-zone fire model
hole size and the Shock Grade Curve to predict the spread of fire and smoke
input: ship target method to measure effect of shock inside through the ship and to the external
SURVIVE offers a versatile target the ship. The grade curves predict the environment. It tracks boundary
definition capability. The SURVIVE target shock-induced motion of a particular temperatures, conduction through
description starts with a triangulated outer piece of structure. Hard-mounted boundaries and allows different insulation
skin surrounding internal structure made equipment experiences the full effect of schemes to be applied. The model responds
up of cuboid shaped building blocks. These this motion, whilst un-mounted items dynamically to changes in the scenario
simple blocks are joined together to create can be thrown through the air and collide (such as doors being opened and closed)
the complex compartmentalisation seen with structure or other equipment. Where and considers the effects of manual or
in modern warships. Doors and hatches shock mounts are installed to protect automatic fire fighting.
are represented as openings in internal or items SURVIVE carries out an assessment As SURVIVE simulates the spread
external structure. of mount response. of damage through the ship, it tracks
Items of equipment (including crew) are SURVIVE uses a spring-beam the effect of primary and secondary
represented as a series of simple shapes, representation of the longitudinal mechanisms on stowed munitions. By
or can be built up in any user-specified structure of a ship or submarine to assess comparing cumulative damage against
shape if required. Equipment items are the effect of an oscillating underwater initiation criteria specific to the munition
built up into logical systems representing bubble of explosive products. This predicts involved, it can predict the level of reaction
the functionality of the ship. The resulting the maximum bending imposed. from a simple burn to a full detonation.
fault trees give a clear visual impression Flood water can propagate through The damage due to this new event is then
of what must be available for the ship to damaged structure and intact simulated to give an overall effect.
conduct a particular function. non-watertight structure. At each time The effect of each damage mechanism
step SURVIVE calculates the flooded on each item of equipment is predicted,
input: weapon state of each compartment and the with a set of kill criteria specific to each
One or more threat weapons can be defined new static attitude accounting for the category/ subcategory combination
in a given scenario. The main properties floodwater. Fire fighting and pumping giving the probability that a given item is
of each threat that can be included are: occurring during the recoverability phase damaged. The equipment vulnerabilities
geometry; fuzing; charge; fragmentation are included. At specified intervals a static are combined to give the vulnerability of
types; fragmentation distribution; fuel; stability check is undertaken, accounting each system using a Monte Carlo analysis
and shaped charge. for the free surface effect and applied of the system fault trees.
SURVIVE contains a number of wind heeling lever. Crew movements are simulated on a
algorithms for predicting the level of The structural representation of the network of paths making up routes. The
blast applied by an explosive charge and ship in SURVIVE includes information speed that a particular crew member
the propagation of that blast internally on the type and spacing of stiffeners at can take depends on factors such as
or externally. The spread of blast through any location, which can be built up very congestion, ship’s attitude, equipment
doors, hatches, windows and patches is an quickly in an easy-to-user interface. By being carried and presence of smoke.
important factor. The visualisation of blast combining this with rules dictating the When a path runs through a door or hatch
can be coloured by severity. Numerical effect of joints and hull shape SURVIVE opening and closing times are important.
levels of blast pressure experienced can can calculate the ultimate strength of A queue may form at one or both sides of
also be interrogated. the ship at any longitudinal location in the opening.
SURVIVE generates many thousands the intact and damaged states. This is The crew movement capability can
of test lines orientated around the threat’s compared to the wave induced bending be used for evacuation analysis and
primary axis to represent possible initial moment at the given sea state, accounting the simulation of recoverability – in
paths for any fragmentation. The required for any flooding present, to establish when undertaking damage searches, changing
fragmentation distribution is allocated
to these test lines probabilistically before
blast spread.
SURVIVE begins to trace the lines away
from the detonation point. Each time a
line interacts with structure or equipment
SURVIVE tests for penetration, ricochet
and also equipment damage where
appropriate.
Underwater detonations cause
waterborne shock waves that can damage
both structure and installed equipment.
Warship Technology March 2010 31
WT_Mar-2010_p30-31-32.indd 31 23/02/2010 16:01:13
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