Evaluation of distortions in laser welded shipbuilding parts using local-global finite element approach

In recognition of the differences of scale between the welding pool and the heat affected zone along the welding line on one hand, and the overall size of the components being welded on the other, a local-global finite element approach was developed for the evaluation of distortions in laser welded shipbuilding parts. The approach involves the tandem use of a 'local' and a 'global' step. The local step involves a three-dimensional finite element model for the simulation of the laser welding process using the Sysweld finite element code, which takes into account thermal, metallurgical, and mechanical aspects. The simulation of the laser welding process was performed using a non-linear heat transfer analysis, based on a keyhole formation model, and a coupled transient thermomechanical analysis, which takes into account metallurgical transformations using the temperature dependent material properties and the continuous cooling transformation diagram. The size and shape of the keyhole used in the local finite element analysis was evaluated using a keyhole formation model and the Physica finite volume code. The global step involves the transfer of residual plastic strains and the stiffness of the weld obtained from the local model to the global analysis, which then provides the predicted distortions for the whole part. This newly developed methodology was applied to the evaluation of global distortions due to laser welding of stiffeners on a shipbuilding part. The approach has been proved reliable in comparison with experiments and of practical industrial use in terms of computing time and storage.

An intelligent assistant for design and material engineers in the submarine cable industry

This paper describes an industrial application of case-based reasoning in engineering. The application involves an integration of case-based reasoning (CBR) retrieval techniques with a relational database. The database is specially designed as a repository of experiential knowledge and with the CBR application in mind such as to include qualitative search indices. The application is for an intelligent assistant for design and material engineers in the submarine cable industry. The system consists of three components; a material classifier and a database of experiential knowledge and a CBR system is used to retrieve similar past cases based on component descriptions. Work has shown that an uncommon retrieval technique, hierarchical searching, well represents several search indices and that this techniques aids the implementation of advanced techniques such as context sensitive weights. The system is currently undergoing user testing at the Alcatel Submarine Cables site in Greenwich. Plans are for wider testing and deployment over several sites internationally.

Safer by design: using computer simulation to predict the evacuation performance of passenger ships

When designing a new passenger ship or modifiying an existing design, how do we ensure that the proposed design is safe from an evacuation point of view? In the building and aviation industries, computer based evacuation models are being used to tackle similar issues. In these industries, the traditonal restrictive prescriptive approach to design is making way for performance based design methodologies using risk assessment and computer simulation. In the maritime industry, ship evacuation models off the promise to quickly and efficiently bring these considerations into the design phase, while the ship is "on the drawing board". This paper describes the development of evacuation models with applications to passenger ships and further discusses issues concerning data requirements and validation.

The development of an advanced ship evacuation simulation software product and associated large scale testing facility for the collection of human shipboard behaviour data

When designing a new passenger ship or modifying an existing design, how do we ensure that the proposed design and crew emergency procedures are safe from an evacuation point of view? In the wake of major maritime disasters such as the Herald of Free Enterprise and the Estonia and in light of the growth in the numbers of high density, high-speed ferries and large capacity cruise ships, issues concerned with the evacuation of passengers and crew at sea are receiving renewed interest. In the maritime industry, ship evacuation models offer the promise to quickly and efficiently bring evacuation considerations into the design phase, while the ship is "on the drawing board". maritimeEXODUS-winner of the BCS, CITIS and RINA awards - is such a model. Features such as the ability to realistically simulate human response to fire, the capability to model human performance in heeled orientations, a virtual reality environment that produces realistic visualisations of the modelled scenarios and with an integrated abandonment model, make maritimeEXODUS a truly unique tool for assessing the evacuation capabilities of all types of vessels under a variety of conditions. This paper describes the maritimeEXODUS model, the SHEBA facility from which data concerning passenger/crew performance in conditions of heel is derived and an example application demonstrating the models use in performing an evacuation analysis for a large passenger ship partially based on the requirements of MSC circular 1033.

Fire safety engineering and ship design using advanced fire and evacuation simulation

When designing a new passenger ship or modifying an existing design, how do we ensure that the proposed design and crew emergency procedures are safe from an evacuation resulting from fire or other incident? In the wake of major maritime disasters such as the Scandinavian Star, Herald of Free Enterprise, Estonia and in light of the growth in the number of high density, high-speed ferries and large capacity cruise ships, issues concerning the evacuation of passengers and crew at sea are receiving renewed interest. Fire and evacuation models with features such as the ability to realistically simulate the spread of heat and smoke and the human response to fire as well as the capability to model human performance in heeled orientations linked to a virtual reality environment that produces realistic visualisations of the modelled scenarios are now available and can be used to aid the engineer in assessing ship design and procedures. This paper describes the maritimeEXODUS ship evacuation and the SMARTFIRE fire simulation model and provides an example application demonstrating the use of the models in performing fire and evacuation analysis for a large passenger ship partially based on the requirements of MSC circular 1033

Analysing the evacuation procedures employed on a Thames passenger boat using the maritimeEXODUS evacuation model

On the 19 June 2001, a Thames passenger/tour boat underwent several evacuation trials. This work was conducted in order to collect data for the validation of marine-based computer models. The trials involved 111 participants who were distributed throughout the vessel. The boat had two decks and two points of exit from the lower deck placed on either side of the craft, forward and aft. The boat had a twin set of staircases towards the rear of the craft, just forward of the rear exits. maritimeEXODUS was used to simulate the full-scale evacuation trials conducted. The simulation times generated were compared against the original results and categorised according to the exit point availability. The predictions closely approximate the original results, differing by an average of 6.6% across the comparisons, with numerous qualitative similarities between the predictions and experimental results. The maritimeEXODUS evacuation model was then used to examine the evacuation procedure currently employed on the vessel. This was found to have potential to produce long evacuation times. maritimeEXODUS was used to suggest modifications to the mustering procedures. These theoretical results suggest that it is possible to significantly reduce evacuation times.

Using an interactive parallelisation toolkit to parallelise an ocean modelling code

This paper describes an interactive parallelisation toolkit that can be used to generate parallel code suitable for either a distributed memory system (using message passing) or a shared memory system (using OpenMP). This study focuses on how the toolkit is used to parallelise a complex heterogeneous ocean modelling code within a few hours for use on a shared memory parallel system. The generated parallel code is essentially the serial code with OpenMP directives added to express the parallelism. The results show that substantial gains in performance can be achieved over the single thread version with very little effort.

Integrated fire and evacuation in maritime environments

When designing a new passenger ship or modifying an existing design, how do we ensure that the proposed design and crew emergency procedures are safe from an evacuation resulting from fire or other incident? In the wake of major maritime disasters such as the Scandinavian Star, Herald of Free Enterprise, Estonia and in light of the growth in the numbers of high density high-speed ferries and large capacity cruise ships, issues concerning the evacuation of passengers and crew at sea are receiving renewed interest. Fire and evacuation models with features such as the ability to realistically simulate the spread of fire and fire suppression systems and the human response to fire sas well as the capability to model human performance in heeled orientations linked to a virtual reality environment that produces realistic visualisations of modelled scenarios are now available and can be used to aid the engineer in assessing ship design and procedures. This paper describes the maritmeEXODUS ship evacuation and the SMARTFIRE fire simulation model and provides an example application demonstrating the use of the models in performing fire and evacuation analysis for a large passenger ship partially based on the requirements of MSC circular 1033. The fire simulations include the action of a water mist system.

Simulation of ship evacuation and passenger circulation

This paper describes work carried out in the FIRE EXIT research project. FIRE EXIT aims to develop an Evacuation Simulator, capable of addressing issues of mustering, ship motions, fire and abandonment. In achieving these aims, FIRE EXIT took as its starting point the state-of-the-art in ship evacuation simulation (the maritimeEXODUS software), fire simulation (the SMARTFIRE software) and large-scale experimental facilities (the SHEBA facility). It then significantly enhanced these capabilities. A number of new technologies have been developed in achieving these objectives. The innovations include directly linking CFD fire simulation with evacuation and abandonment software and automatic data transfer from concept design software allowing rapid generation of ship simulation models. Software usability was augmented by a module for interpretation of evacuation software output. Enhancements to a ship evacuation testing rig have resulted in a unique facility, capable of providing passenger movement data for realistic evacuation scenarios and large scale tests have provided meaningful data for the evacuation simulation.

Advanced evacuation simulation software and its use in warships

The newly formed Escape and Evacuation Naval Authority regulates the provision of abandonment equipment and procedures for all Ministry of Defence Vessels. As such, it assures that access routes on board are evaluated early in the design process to maximize their efficiency and to eliminate, as far as possible, any congestion that might occur during escape. This analysis can be undertaken using a computer-based simulation for given escape scenarios and replicates the layout of the vessel and the interactions between each individual and the ship structure. One such software tool that facilitates this type of analysis is maritimeEXODUS. This tool, through large scale testing and validation, emulates human shipboard behaviour during emergency scenarios; however it is largely based around the behaviour of civilian passengers and fixtures and fittings of merchant vessels. Hence there existed a clear requirement to understand the behaviour of well-trained naval personnel as opposed to civilian passengers and be able to model the fixtures and fittings that are exclusive to warships, thus allowing improvements to both maritimeEXODUS and other software products. Human factor trials using the Royal Navy training facilities at Whale Island, Portsmouth were recently undertaken to collect data that improves our understanding of the aforementioned differences. It is hoped that this data will form the basis of a long-term improvement package that will provide global validation of these simulation tools and assist in the development of specific Escape and Evacuation standards for warships. © 2005: Royal Institution of Naval Architects.

An analysis of passenger performance on stairs and upper deck slides during evacuation trials: a report from the VERRES project

This paper reports on research work undertaken for the European Commission funded study GMA2/2000/32039 Very Large Transport Aircraft (VLTA) Emergency Requirements Research Evacuation Study (VERRES). A particular focus of VERRES was on evacuation issues and several large-scale evacuation trials were conducted in the CRANFIELD simulator. This paper addresses part of the research undertaken for Work Package 3 by the University of Greenwich with a focus on the analysis of the data concerning passenger use of stairs and passenger exit hesitation time analysis for upper deck slides.

Data collection in support of the modelling of naval vessels

Evacuation analysis of passenger and commercial shipping can be undertaken using computer-based simulation tools such as maritimeEXODUS. These tools emulate human shipboard behaviour during emergency scenarios; however it is largely based around the behaviour of civilian passengers and fixtures and fittings of merchant vessels. If these tools and procedures are to be applied to naval vessels there is a clear requirement to understand the behaviour of well-trained naval personnel interacting with the fixtures and fittings that are exclusive to warships. Human factor trials using Royal Navy training facilities were recently undertaken to collect data to improve our understanding of the performance of naval personnel in warship environments. The trials were designed and conducted by staff from the Fire Safety Engineering Group (FSEG) of the University of Greenwich on behalf of the Sea Technology Group (STG), Defence Procurement Agency. The trials involved a selection of RN volunteers with sea-going experience in warships, operating and traversing structural components under different angles of heel. This paper describes the trials and some of the collected data.