Papers by Bruce Cartwright
Bulletin of the American Physical Society, 2019
generation in channels is usually achieved through wavemakers (moving paddles) acting on the surf... more generation in channels is usually achieved through wavemakers (moving paddles) acting on the surface of water. Although practical for this purpose, wavemakers have issues: they perform poorly in the generation of long waves and create evanescent waves in their vicinity. In this talk, we introduce a framework for wave generation through the action of an underwater multi-point mechanism. We analyze the linear response of waves in a uniform channel in terms of the frequency and wavelength of the bottom action. The system behaves as a long-pass filter in space and a high-pass filter in time with a sharp resonance limited by viscosity. The framework naturally solves the problem of the performance for long waves and reduces evanescent waves to thin boundary layers at the bottom. We also show that a proper synchronization of an orbital motion on the bottom can produce waves that mimic deep water waves with great accuracy. This last feature has been proved to be useful and efficient to study fluid-structure interaction in simulations based on smoothed-particle hydrodynamics.
Intra-ply shear locking in finite element analyses of woven fabric forming processes
Composites Part A: Applied Science and Manufacturing, 2006
This study was motivated by the observation of physically unrealistic wrinkles, named spurious wr... more This study was motivated by the observation of physically unrealistic wrinkles, named spurious wrinkles, seen in finite element simulations of diaphragm forming of woven fabrics. Essential intra-ply shear modes for 4-node and 3-node shell elements were investigated. When these essential modes, which show dependency on mesh orientations, are not fully implemented, the stiffness of an element may be overestimated. The
Composite Structures, 2008
A validated simulation methodology has been developed to support the bird-strike certification of... more A validated simulation methodology has been developed to support the bird-strike certification of the carbon fibre epoxy composite, moveable trailing edge (MTE) of the Boeing 787 Dreamliner. The explicit finite element software PAM-CRASH TM was selected to perform the simulations utilising the advanced composite material, fastener and smooth particle hydrodynamic bird models available in the code. The modelling procedures were validated firstly through comparison with existing test data and secondly through the testing and analysis of representative structures. Subsequent use of the validated modelling procedures during the analysis of the MTE facilitated the evaluation of numerous bird-strike scenarios, leading to improved design efficiency and safety, while significantly reducing certification costs.
This paper presents a numerical modelling technique for the prediction and understanding of struc... more This paper presents a numerical modelling technique for the prediction and understanding of structural degradation of maritime assets, including defence vessels and offshore structures. The response of such structures to specific sea-state conditions is considered, accounting for the effect of the structure under degradation processes such as cracks, corrosion and accidents. The paper specifically considers the stresses developed in a ship traversing ocean waves using the technique of fluid-structure interaction by combination of smoothed particles for the hydrodynamics (SPH) with finite elements (FE) for the structure [1]. Selected aspects of the employed SPH and the coupling approach will be discussed. The time-varying stresses are the consequences of the hydrodynamic forces on the ship, the resulting ship motions, and the reaction of the ship structure to those motions. The wave height and wave period of the sea state are specified in the simulation. The simulations are based on ...
One of the most important aspects of an amphibious ship is the ability to safely and swiftly tran... more One of the most important aspects of an amphibious ship is the ability to safely and swiftly transport and transfer large numbers of troops and their associated equipment from sea to shore. Such transfers are usually conducted using landing craft, which are loaded using a flooded well dock at the stern of the ship. Hence, the behaviour of landing craft within the flooded well dock is of critical importance to the operators of an amphibious ship. This paper describes, and presents results from, an investigation into the effect of the design of the well dock on the motions of a landing craft when operating in a seaway.
Fluids, 2021
Experimental wave generation in channels is usually achieved through wavemakers (moving paddles) ... more Experimental wave generation in channels is usually achieved through wavemakers (moving paddles) acting on the surface of the water. Although practical for engineering purposes, wavemakers have issues: they perform poorly in the generation of long waves and create evanescent waves in their vicinity. In this article, we introduce a framework for wave generation through the action of an underwater multipoint mechanism: the pedal-wavemaking method. Our multipoint action makes each point of the bottom move with a prescribed pedalling-like motion. We analyse the linear response of waves in a uniform channel in terms of the wavelength of the bottom action. The framework naturally solves the problem of the performance for long waves and replaces evanescent waves by a thin boundary layer at the bottom of the channel. We also show that proper synchronisation of the orbital motion on the bottom can produce waves that mimic deep water waves. This last feature has been proved to be useful to st...
Recent Features and Industrial Applications of the Hybrid SPH-FE Method
International Journal of Computational Fluid Dynamics
Finite element simulations of the doublediaphragm forming process
Revue Europeenne Des Elements Finis, Apr 26, 2012
ABSTRACT This document provides a comprehensive evaluation of finite element simulations of doubl... more ABSTRACT This document provides a comprehensive evaluation of finite element simulations of double diaphragm forming of CF/EP plain weave prepreg. The simulations were performed using the PAM-FORM software, and incorporated critical advances recently achieved in composite forming simulations. The material properties were obtained from characterization tests, or estimated in conjunction with rationalization analyses. By using only one set of material and simulation parameters, the best-match simulations correlate well with all four experimental trials of different setups, which include one good and one wrinkled forming trail of rudder rib shape, and one good and one wrinkled forming trial of a simple cup shape. The simulations also highlight the effects of contact penalty, and the sensitivity to inter-ply friction, and re-confirm the necessity to scale-up the measured intra-ply shearing stiffness.
Method and apparatus for welding of polymer composite components
Smoothed Particle Hydrodynamics (SPH) is used to model the ditching of a helicopter. Helicopters ... more Smoothed Particle Hydrodynamics (SPH) is used to model the ditching of a helicopter. Helicopters have a high centre of gravity, are not integrally watertight so tend to roll over and sink within seconds of landing on the water surface. Modern helicopters employ Emergency Flotation Systems (EFS) that are essentially large air-bags to provide increased buoyancy and stability to the helicopter, thereby enhancing occupant survival rates. A hybridised finite element code that includes SPH elements, rigid finite elements, flexible finite elements, sliding contact interface algorithms and air-bag simulation tools from the automotive industry is used to demonstrate the behaviour of the complex fluid-structure interaction scenario of a helicopter landing on water with and without inflating air-bags. I.
Thermo-forming and structural analysis of combat helmets
Journal of Manufacturing Science and Engineering, 2015
To reduce combat casualties, military helmets are designed to provide protection against projecti... more To reduce combat casualties, military helmets are designed to provide protection against projectiles. Modern combat helmets are constructed of relatively lightweight composite materials that provide ballistic protection to the soldier. The manufacture of most composite helmets is labor intensive and involves the manual application and smoothing of individual layers of reinforcement to a concave mold surface. The recently developed double diaphragm deep drawing thermoforming process turns as-purchased, flat-form composite materials into structurally efficient three-dimensional shapes. Using this process, prototype shells have been produced and subsequently tested structurally. The success of the outcome has been greatly assisted through the use of specialized virtual prototyping techniques to provide insight into the thermoforming process of the shells and subsequently their structural performance by accounting for the actual fiber orientations of those finished shells.
Finite element simulations of the double-diaphragm forming process. Comparisons with experimental trials
Revue européenne des éléments finis, 2005
This document provides a comprehensive evaluation of finite element simulations of double diaphra... more This document provides a comprehensive evaluation of finite element simulations of double diaphragm forming of CF/EP plain weave prepreg. The simulations were performed using the PAM-FORM software, and incorporated critical advances recently achieved in composite forming simulations. The material properties were obtained from characterization tests, or estimated in conjunction with rationalization analyses. By using only one set of material and
Hydrodynamics and fluid-structure interaction by coupled SPH-FE method
Journal of Hydraulic Research, 2009
... novel approach to generate free surface waves in an arbitrary domain and validation for secon... more ... novel approach to generate free surface waves in an arbitrary domain and validation for second ... (1999) Simulation results for this case using a commercial, finite volume based CFD code have ... Figure 11 Comparison of RAO's from simulation, tank tests and potential flow methods ...
The modelling of landing craft motions inside a flooded Well dock using smoothed particle hydrodynamics
Pacific 2006 …, 2006
... Full Text PDF (520kb). To cite this article: Cartwright, Bruce; McGuckin, Damian; Turner, Ter... more ... Full Text PDF (520kb). To cite this article: Cartwright, Bruce; McGuckin, Damian; Turner, Terry and Cannon, Stuart. The Modelling of Landing Craft Motions inside a flooded Well Dock Using Smoothed Particle Hydrodynamics [online]. ... (1) Pacific ESI Unit 22 Campbell St. ...
9th Symposium on …, 2004
Examples of challenging scenarios for the analysis of ship performance in waves are discussed. Th... more Examples of challenging scenarios for the analysis of ship performance in waves are discussed. The software tool that allows these scenarios to be analysed in a conceptually clean and coupled numerical problem, employs smoothed particle hydrodynamic techniques (SPH) integrated into an existing explicit finite element structural analysis code.
Composite Structures, 2008
A validated simulation methodology has been developed to support the bird-strike certification of... more A validated simulation methodology has been developed to support the bird-strike certification of the carbon fibre epoxy composite, moveable trailing edge (MTE) of the Boeing 787 Dreamliner. The explicit finite element software PAM-CRASH TM was selected to perform the simulations utilising the advanced composite material, fastener and smooth particle hydrodynamic bird models available in the code. The modelling procedures were validated firstly through comparison with existing test data and secondly through the testing and analysis of representative structures. Subsequent use of the validated modelling procedures during the analysis of the MTE facilitated the evaluation of numerous bird-strike scenarios, leading to improved design efficiency and safety, while significantly reducing certification costs.
Finite element simulations of the doublediaphragm forming process
This document provides a comprehensive evaluation of finite element simulations of double diaphra... more This document provides a comprehensive evaluation of finite element simulations of double diaphragm forming of CF/EP plain weave prepreg. The simulations were performed using the PAM-FORM software, and incorporated critical advances recently achieved in composite forming simulations. The material properties were obtained from characterization tests, or estimated in conjunction with rationalization analyses. By using only one set of material and
Intra-ply shear locking in finite element analyses of woven fabric forming processes
Composites Part A-applied Science and Manufacturing, 2006
This study was motivated by the observation of physically unrealistic wrinkles, named spurious wr... more This study was motivated by the observation of physically unrealistic wrinkles, named spurious wrinkles, seen in finite element simulations of diaphragm forming of woven fabrics. Essential intra-ply shear modes for 4-node and 3-node shell elements were investigated. When these essential modes, which show dependency on mesh orientations, are not fully implemented, the stiffness of an element may be overestimated. The
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Papers by Bruce Cartwright