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Giles Thomas - One of the best experts on this subject based on the ideXlab platform.
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Machine Learning and Cloud Computing for Remote Monitoring of Wave Piercing Catamarans: A Case Study using MATLAB on Amazon Web Services
Smart Ship Technology Conference 2020, 2020Co-Authors: Babak Shabani, Jason Ali-lavroff, Damien Holloway, Spiridon Penev, Daniele Dessi, Giles ThomasAbstract:Wave load cycles, wet-deck slamming events, accelerations and motion comfort are important considerations for high- speed Catamarans operating in moderate to large waves. This paper provides an overview of data analytics methods and cloud computing resources for remotely monitoring motions and structural responses of a 111 m high-speed Catamaran. To satisfy the data processing requirements, MATLAB Reference Architectures on Amazon Web Services (AWS) were used. Such combination enabled fast parallel computing and advanced feature engineering in a time-efficient manner. A MATLAB Production Server on AWS has been set up for near real-time analytics and execution of functions developed according to the class guidelines. A case study using Long Short-Term Memory (LSTM) networks for ship speed and Motion Sickness Incidence (MSI) is provided and discussed. Such data architecture provides a flexible and scalable solution, leading to deeper insights through big data processing and machine learning, which supports hull monitoring functions as a service.
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slam loads and pressures acting on high speed wave piercing Catamarans in regular waves
Marine Structures, 2019Co-Authors: B Shabani, D S Holloway, J Lavroff, Michael R Davis, Giles ThomasAbstract:Slamming loads and pressures on high-speed Catamarans with a centre bow (CB) differ from those on conventional Catamarans with flat deck structures. The latter are well covered by class rules, which provide empirical formulae to calculate the design slamming pressure. An experimental study was therefore performed to quantify slamming pressures in the archways between bow and main hulls and the CB slamming force on a 112m wave piercing Catamaran. The CB length was systematically varied on a 2.5m hydroelastic segmented Catamaran model, which was tested in regular head sea waves at a speed of 2.89 m/s, full-scale equivalent of 38 knots. Slamming pressures were measured by 18 pressure transducers fitted into the CB, while data obtained from CB accelerometers and load cells enabled identification of the slamming force. The results indicate that slamming loads increase significantly with increasing CB length while the maximum peak slamming pressures varies to a lesser extent. It was also found that wave encounter frequency has a strong effect on the location of maximum pressure along the CB, considerably more so than any influence of CB configuration. The distribution of the peak pressures within the CB archway shows that the inboard peak pressures are larger than those at the top of the arch and the outboard locations.
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fluid structure interaction simulation of slam induced bending in large high speed wave piercing Catamarans
Journal of Fluids and Structures, 2018Co-Authors: Jj Mcvicar, J Lavroff, Giles ThomasAbstract:A ship in waves may experience a water impact event known as a slam. In this paper, slam-induced bending of wave-piercing Catamarans in head seas is predicted by way of fluid–structure interaction simulations. The flow field during slamming of a wave-piercing Catamaran is highly non-linear and cannot be accurately captured using potential flow methods as a result of the interactions between the flow fields produced by water entry of the separate demihulls and centre bow. Thus, the Reynolds-Averaged Navier–Stokes (RANS) equations are solved for rigid body motion of a vessel at model-scale. Verification and validation is conducted using model-scale data from a Hydroelastic Segmented Model (HSM). One-way and two-way interactions are computed considering vibration of the hull girder. In the case of one-way interactions, the computed fluid loads affect the structure, but the structural response does not affect the fluid domain solution whereas for the two-way interactions the structural response affects the fluid solution. A new method for capturing the non-linear time variation in added mass is developed and deemed necessary when computing one-way interactions, primarily as a result of the large changes in forward wetted area present for a wave-piercing Catamaran. It is shown that two-way interaction simulation is not needed for predicting the slam induced hull girder loads. One-way interaction simulation can therefore be used allowing reduced computational effort.
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wave slamming loads on wave piercer Catamarans operating at high speed determined by hydro elastic segmented model experiments
Marine Structures, 2013Co-Authors: J Lavroff, D S Holloway, Giles ThomasAbstract:Catamaran vessels operating at high-speed can be exposed to deck diving and bow damage and one resolution of this problem is the wave-piercer design of INCAT Tasmania. Owing to the complexity of the unsteady non-linear flow in the bow area during large wave encounter model testing has been undertaken to identify the peak dynamic slam loads on the ship structure. This paper provides experimental benchmark information relating to the wave slam loads on wave-piercing Catamaran ferries. Since the time frames of transient slam loadings and whipping vibration of the entire hull in its first bending mode are similar it is important that the test model replicates the whipping response and therefore needs to be a hydroelastic model. A 2.5m hydro-elastic segmented Catamaran model has been developed based on the 112 m INCAT Tasmania wave-piercer Catamaran to establish the peak wave slamming loads acting on the full-scale vessel. Towing tank tests were performed in regular seas at a maximumfull-scale operating speed of 38 knots. The model was instrumented to measure the dynamic slam loads acting on the centre bowand vertical bending moments acting in the demihulls of the Catamaran model as a function of wave frequency and wave height. Peak slam loads measured on the centre bow were found to approach the total weight of the model, this being a broadly similar result to the peak loads measured at full-scale. It was found that global dimensionless heave and pitch accelerations peaked in the same range of encounter frequency as did the peak slam load.
D S Holloway - One of the best experts on this subject based on the ideXlab platform.
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centre bow and wet deck design for motion and load reductions in wave piercing Catamarans at medium speed
Ships and Offshore Structures, 2021Co-Authors: B Shabani, D S Holloway, J Lavroff, G A ThomasAbstract:For wave piercing Catamarans, the centre bow length and tunnel clearance are important design factors for slamming, passenger comfort and deck diving. This experimental study determined the influence of centre bow (CB) and wet-deck geometry on their motions and loads at reduced speed using five configurations. A 2.5 m hydroelastic segmented Catamaran model was tested in regular head seas in wave heights equivalent to 2.7 m, 4.0 m and 5.4 m at full scale. Higher wet-decks had higher vertical accelerations but reduced slamming loads. The greatest peak vertical CB loads ranged between 18–105% of the total hull weight. Regression models were obtained for the vertical loads and bending moments. A reduction of speed from 38 knots to 20 knots reduces the maximum slam loads by approximately 30% in regular waves. Considering both low and high speeds, the Short CB was found to be a consistent design for slamming reduction.
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Slam load estimation for high-speed Catamarans in irregular head seas by full-scale computational fluid dynamics
'Elsevier BV', 2021Co-Authors: Ali-lavroff J, D S Holloway, Davis MrAbstract:Global loads acting on high-speed wave-piercing Catamarans are investigated using computational fluid dynamics (CFD). Catamaran vessels are subjected to load cases that are not present on mono-hull vessels, such as transverse bending moment, pitch connecting moment and splitting force. As the speed and size of a Catamaran increases the severity of loads rises with slam induced effects. Full-scale CFD simulation is undertaken to investigate the pressure distributions and resultant global loads acting on the 98 m INCAT wave-piercer Catamaran HSV2 Swift, validated against sea trial tests. Rigid body dynamics are then applied to estimate the internal loads at different sections of the vessel based on the relative hydrodynamic and inertial force distributions. The estimated global loads are then checked according to DNV GL rules by comparing “design load limits”. Global loads are estimated for the 98 m INCAT HSV2 Swift Catamaran in headseas at a forward speed of 20 knots. Splitting forces are found to have a longitudinal distribution along the Catamaran hull, which causes prying moments. Peak values for LBM are examined relative to corresponding instantaneous wave height prior to the slam event. In addition, it is found that pitch acceleration has a linear correlation with LBM slam loads
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Machine learning and cloud computing for remote monitoring of wave piercing Catamarans: a case study using Matlab on Amazon web services
The Royal Institution of Naval Architects, 2020Co-Authors: Shabani B, D S Holloway, Ali-lavroff J, Penev S, Dessi D, Thomas GAbstract:Wave load cycles, wet-deck slamming events, accelerations and motion comfort are important considerations for high-speed Catamarans operating in moderate to large waves. Although developing a hull monitoring system according to classification guidelines for such vessels is broadly acceptable, the data processing requirements for outputs such as rainflow counting, filtering, probability distribution, fatigue damage estimation and warning due to slamming can be as sophisticated to implement as the system components themselves. Advanced analytics such as machine learning and deep learning data pipelines will also create more complexities for such systems, if included. This paper provides an overview of data analytics methods and cloud computing resources for remotely monitoring motions and structural responses of a 111 m high-speed Catamaran. To satisfy the data processing requirements, MATLAB Reference Architectures on Amazon Web Services (AWS) were used. Such combination enabled fast parallel computing and advanced feature engineering in a time-efficient manner. A MATLAB Production Server on AWS has been set up for near real-time analytics and execution of functions developed according to the class guidelines. A case study using Long Short Term Memory (LSTM) networks for ship speed and Motion Sickness Incidence (MSI) is provided and discussed. Such data architecture provides a flexible and scalable solution, leading to deeper insights through big data processing and machine learning, which supports hull monitoring functions as a service
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slam loads and pressures acting on high speed wave piercing Catamarans in regular waves
Marine Structures, 2019Co-Authors: B Shabani, D S Holloway, J Lavroff, Michael R Davis, Giles ThomasAbstract:Slamming loads and pressures on high-speed Catamarans with a centre bow (CB) differ from those on conventional Catamarans with flat deck structures. The latter are well covered by class rules, which provide empirical formulae to calculate the design slamming pressure. An experimental study was therefore performed to quantify slamming pressures in the archways between bow and main hulls and the CB slamming force on a 112m wave piercing Catamaran. The CB length was systematically varied on a 2.5m hydroelastic segmented Catamaran model, which was tested in regular head sea waves at a speed of 2.89 m/s, full-scale equivalent of 38 knots. Slamming pressures were measured by 18 pressure transducers fitted into the CB, while data obtained from CB accelerometers and load cells enabled identification of the slamming force. The results indicate that slamming loads increase significantly with increasing CB length while the maximum peak slamming pressures varies to a lesser extent. It was also found that wave encounter frequency has a strong effect on the location of maximum pressure along the CB, considerably more so than any influence of CB configuration. The distribution of the peak pressures within the CB archway shows that the inboard peak pressures are larger than those at the top of the arch and the outboard locations.
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Global load determination of high‑speed wave‑piercing Catamarans using finite element method and linear least squares applied to sea trial strain measurements
'Springer Science and Business Media LLC', 2019Co-Authors: Lavroff J, D S Holloway, Shabani B, Davis MrAbstract:Twin hull high-speed Catamarans encounter a wide range of sea wave loads. This paper studies the full-scale prediction ofglobal loads on a high-speed Catamaran using linear regression analysis based on finite element results. Load cases basedon Det Norske Veritas rules are applied to a finite element model to derive load–strain transformation. Strain responses areevaluated at 16 different locations on the Catamaran finite element model corresponding to the strain gauges positioned onthe HSV-2 Swift 98m Incat Catamaran during sea trials. A transformation matrix is generated using the concept of ordinaryleast squares, to convert from strain responses to the equivalent DNV global load cases. This is applied to determine globalloads during several sea trial runs in different heading angles and speeds of 10, 20 and 35 knots. These loads then are comparedto show each global load severity at specific speed or heading angle
Hasan Basri, Kevin A. - One of the best experts on this subject based on the ideXlab platform.
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Desain Konsep Kapal Perang Serbu Catamaran Tank Boat Dengan Sistem Penggerak Utama Turbojet Sebagai Kekuatan Pengamanan Wilayah Maritim Indonesia
2018Co-Authors: Hasan Basri, Kevin A.Abstract:Indonesia merupakan negara maritim yang terbesar di dunia dengan 80% dari wilayahnya yang berupa lautan. Luasnya sektor perairan yang mencapai 80% dari seluruh luas wilayah Indonesia, menyebabkan susahnya pengawasan terhadap keamanan dan kedaulatan wilayah NKRI khususnya dalam sektor maritim. Cukup banyak kapal perang asing yang terlambat terdeteksi dan terlanjur masuk ke Indonesia akibat dari kurangnya pengawasan dan cepat tanggap kapal perang negara kita yang hanya memilik 160 unit kapal perang dari 700 kapal yang dibutuhkan. Hal hal yang berkaitan dengan sumber daya alam Indonesia akhir-akhir ini juga sering terjadi masalah, yakni mengenai pencurian SDA di sektor perairan. Ditambah dengan strategisnya posisi Indonesia yang diapit dua samudera dan dua benua yang dapat memicu terjadinya konflik teritorial dengan negara asing. Dibutuhkan armada yang kuat untuk mengusir kehadiran mereka agar tidak terulang kembali.Terobosan yang mulai dilakukan negara untuk memperbaiki masalah ini seperti pembuatan kapal perang lambung ganda serta alusista yang canggih sudah mulai digalakkan.Oleh karena itu untuk memanfaatkan teknologi di bidang perkapalan ini, dibutuhkan desain kosep kapal cepat katamaran yang baik dan cepat tanggap sebagai alusista perang dan pengamanan wilayah maritim Indonesia. Tujuan dari desain kapal Tank Boat ini adalah 1. menentukan operational requirements kapal perang serbu Catamaran Tank Boat dengan Turbojet untuk operasi wilayah perairan Indonesia, 2. Memperoleh ukuran utama kapal perang serbu Catamaran Tank Boat dengan Turbojet, 3. Mendapatkan lines plan dan rencana umum kapal perang serbu Catamaran Tank Boat dengan Turbojet, 4. Mendesain layout awal rencana umum dan model 3D kapal perang serbu Catamaran Tank Boat dengan Turbojet. Dalam proses desain awal kapal perang ini, dilakukan penentuan operational requirement kapal dan ukuran utama kapal yang diperoleh dari metode parent ship dengan ukuran utama LOA=18 m, B=6,6 m, T=1 m. Hasil akhir dari desain ini yakni operational requirement dari Catamaran Tank Boat dengan fungsi dan tugasnya sebagai Fast Patrol Boat armada pemukul bantu yang akan memulai operasinya ketika mendapat perintah dari pusat pertahanan Indonesia dan Patroli penjagaan wilayah maritim Indonesia. Wilayah operasional kapal yakni seluruh perairan Indonesia khususnya ZTE, kecepatan maksimal kapal 55 knot, kecepatan saat pengejaran 45 knot, kecepatan patroli 25 knot. Untuk kemampuan operasional, kapal dapat beroperasi selama 148 menit dengan kecepatan 55 knot, 154 menit dengan kecepatan 45 knot dan 6,5 jam dalam operasi patroli. Untuk Hasil dari analisis teknis didapatkan ukuran utama akhir dengan LOA = 18 m, Lpp = 17.03 m, B = 6.6 m,H = 2.8 m, T = 1 m serta hasil desain Lines plan, General Arrangenment, dan 3D kapal Catamaran Tank Boat. =====================================================================Indonesia is the largest maritime country in the world with 80% of its territory form by the oceans. The area of water sector which reaches 80% of the total area of Indonesia, causing the difficulty of monitoring security and sovereignty of the Indonesian territory, especially in the maritime sector. Many foreign warships that were late detected and already enter Indonesia due to the lack of security and quick response of our state warships. Indonesia only have 160 units of warships of the required 700 ships. Another problem related to Indonesia's natural resources, There are many natural resources stealing evidence this day. Indonesia was located between two oceans and two continents that can trigger territorial conflict with foreign countries. Indonesia needs strong fleets to counter this problem. Indonesia started to build and concept the manufacture of Catamaran warships to defend its territory. With Catamaran technology and turbojet applications on the vessel, it is hoped soon to form new fleets capable and can overcome the problem of security and sovereignty of the country because of its efficiency and good function. Therefore, to utilize technology in the field of shipbuilding, the concept design of a good and quick response Catamaran fast boat is needed as war fleet and secure the maritime territory of Indonesia.The goals of this Tank Boat design were 1. To determine the operational requirements of this Catamaran Tank Boat with Turbojet for Indonesian maritime territory operation, 2. To get the main dimensions of this Catamaran Tank Boat with Turbojet, 3. To get the lines plan and general arrangement of this Catamaran Tank Boat with Turbojet, 4. To design the first layout of general arrangement and design the 3D model of this Catamaran Tank Boat with Turbojet. In the initial design process of this warship, the determination of the operational requirement of the ship and the main size of the ship obtained from the parent ship method with the main size LOA = 18m, B = 6.6, T = 1m. In the initial design process of this warship, the determination of the ship operational requirement and the main size of the ship obtained from the parent ship method with the main size LOA = 18 m, B = 6.6 m, T = 1 m. The final result of this design is operational requirement of Catamaran Tank Boat with its functions and duties as the Fast Patrol Boat fighting fleet that will operated when it got command from the Indonesian center defence and security fleet of Indonesian maritim teritory. The ship operational area are Indonesian maritime teritory especially ZTE, the maximum speed of 55 knots, 45 knots for attack, and 25 knots for patrol mode. For the operational capability the boat has endurance 148 minutes of 55 knots speed, 154 minutes for 45 knots, and 6,5 hour for patrol mode. The results of the technical analysis obtained the final major size with LOA = 18 m, Lpp = 17.03 m, B = 6.6 m, H = 2.8 m, T = 1 m and Lines plan, General Arrangenment and 3D Catamaran Tank Boat
Aryawan, Wasis Dwi - One of the best experts on this subject based on the ideXlab platform.
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Desain Konsep Kapal Perang Serbu Catamaran Tank Boat Dengan Sistem Penggerak Utama Turbojet Sebagai Kekuatan Pengamanan Wilayah Maritim Indonesia
'Lembaga Penelitian dan Pengabdian kepada Masyarakat ITS', 2018Co-Authors: Basri, Kevin Alfinno Hasan, Aryawan, Wasis DwiAbstract:Indonesia merupakan negara maritim yang terbesar di dunia dengan 80% dari wilayahnya yang berupa lautan. Hal ini menyebabkan susahnya pengawasan terhadap keamanan dan kedaulatan wilayah NKRI khususnya dalam sektor maritime. Oleh karena itu dibutuhkan desain kosep kapal cepat katamaran yang baik dan cepat tanggap sebagai alusista perang dan pengamanan wilayah maritim Indonesia. Tujuan dari desain kapal Tank Boat ini adalah 1. menentukan operational requirements kapal perang serbu Catamaran Tank Boat dengan Turbojet, 2. Memperoleh ukuran utama kapal perang serbu Catamaran Tank Boat dengan Turbojet, 3. Mendapatkan lines plan dan rencana umum kapal perang serbu Catamaran Tank Boat dengan Turbojet, 4. Mendesain layout awal rencana umum dan model 3D kapal perang serbu Catamaran Tank Boat dengan Turbojet. Dalam proses desain awal kapal perang ini, dilakukan penentuan operational requirement kapal dan ukuran utama kapal yang diperoleh dari metode parent ship dengan ukuran utama LOA=18 m, B=6,6 m, T=1 m. Hasil akhir dari desain ini yakni operational requirement dari Catamaran Tank Boat dengan fungsi dan tugasnya sebagai Fast Patrol Boat armada pemukul bantu dan patroli penjagaan wilayah maritim Indonesia. Wilayah operasional Kapal, yakni seluruh perairan Indonesia khususnya ZTE, kecepatan maksimal kapal 55 knot, kecepatan saat pengejaran 45 knot, kecepatan patroli 25 knot. Untuk kemampuan operasional, kapal dapat beroperasi selama 148 menit dengan kecepatan 55 knot, 154 menit dengan kecepatan 45 knot dan 6,5 jam dalam operasi patroli. Hasil dari analisis teknis didapatkan ukuran utama akhir dengan LOA = 18 m, Lpp = 17.03 m, B = 6.6 m,H = 2.8 m, T = 1 m serta hasil desain Lines plan, General Arrangenment, dan 3D kapal Catamaran Tank Boa
Jj Mcvicar - One of the best experts on this subject based on the ideXlab platform.
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fluid structure interaction simulation of slam induced bending in large high speed wave piercing Catamarans
Journal of Fluids and Structures, 2018Co-Authors: Jj Mcvicar, J Lavroff, Giles ThomasAbstract:A ship in waves may experience a water impact event known as a slam. In this paper, slam-induced bending of wave-piercing Catamarans in head seas is predicted by way of fluid–structure interaction simulations. The flow field during slamming of a wave-piercing Catamaran is highly non-linear and cannot be accurately captured using potential flow methods as a result of the interactions between the flow fields produced by water entry of the separate demihulls and centre bow. Thus, the Reynolds-Averaged Navier–Stokes (RANS) equations are solved for rigid body motion of a vessel at model-scale. Verification and validation is conducted using model-scale data from a Hydroelastic Segmented Model (HSM). One-way and two-way interactions are computed considering vibration of the hull girder. In the case of one-way interactions, the computed fluid loads affect the structure, but the structural response does not affect the fluid domain solution whereas for the two-way interactions the structural response affects the fluid solution. A new method for capturing the non-linear time variation in added mass is developed and deemed necessary when computing one-way interactions, primarily as a result of the large changes in forward wetted area present for a wave-piercing Catamaran. It is shown that two-way interaction simulation is not needed for predicting the slam induced hull girder loads. One-way interaction simulation can therefore be used allowing reduced computational effort.
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Slam induced bending of high-speed wave-piercing Catamarans
2017Co-Authors: Jj McvicarAbstract:The unique geometry of wave-piercing Catamarans causes the slamming process to be complex and challenging to predict. The overall slam generally consists of multiple sequential events (demihull bottom slam, centre bow entry and wet-deck arch slam), which impart energy to the structure on differing spatial and temporal scales. In this thesis, the relationship between the slam impact and the resulting bending response of wave-piercing Catamarans was investigated through analytical investigations and numerical simulation. A simplified analytical model of the hull girder being exposed to impact loads was developed and this showed that, compared to conventional craft, the relatively shorter slam duration has the potential to excite higher order bending modes which may contribute significantly to the distribution and magnitude of the hull girder bending moment. One-way and two-way coupled fluid structure interaction simulations accounting for global hull bending, but not local panel flexibility, were established to simulate the slamming behaviour of Catamarans. The wet and dry structural systems were identified by input-output system identification experiments conducted on a 2.5m hydroelastic segmented model. A new method for evaluating and accounting for the time variation in hull added mass was developed and implemented in the one-way coupled simulations. The simulations were verified and validated against prior experimental data in regular head seas. The one-way coupled simulations were found to be sufficient to capture the hull response over a wide range of encounter frequencies. Compared to the two-way simulations this significantly reduced the computational resource requirements and computation time. Allowing for the time variation of added mass in the one-way coupled simulations captured temporal variation in whipping frequency but had a relatively small effect on the bending response amplitudes. The effects of global hydroelasticity were thus found to be small, however, increased hull flexibility was found to appreciably reduce the peak slamming forces acting on the model. From the simulation output data, a method for estimating the transient forces acting on the hydroelastic segmented Catamaran model from the hull bending and global motion response was developed. It is proposed that using this method would lead to significant weight reduction for future hydroelastic scale models. This would allow experimental slamming characteristics to be considered at reduced displacements or facilitate inclusion of additional instrumentation. The contributions to bending from each of the events within the overall slam were estimated from simulation and it was shown that the centre bow entry and arch slam are the largest contributors to hull bending. Centre bow entry was found to be non-impulsive in relation to the hull girder frequencies, acting to generate a pre-strained hull girder prior to each arch slam. The rapid onset and release of the arch slam was found to cause high frequency excitation; exciting modes with natural frequencies up to four times the fundamental longitudinal bending frequency and having significant implications for the design hull girder bending distribution - particularly for hull sections in the vicinity of the slam location