SEAWAY LOADS INTEGRATION WITH SHIP FINITE ELEMENT ANALYSIS
Presented by the SNAME T&R Hydrodynamics, Ship Structures, Ship Design and Ship Production Committees
The Technical & Research (T&R) Committee in collaboration with its Hydrodynamics, Ship Structures, Ship Design, and Ship Production Committees is embarking on a series of monthly webinars to inform the ship design and shipbuilding community of the state-of-art of predicting seaway loads and their crucial impact on ship design and construction. The webinar series will also identify shortcomings of existing prediction methods and conclude with an in-person workshop to gain consensus on drafting a roadmap for developing reliable methods for predicting seaway loads in early-stage ship design.This webinar presents the solution MAESTRO-Wave and its post-processors Extreme Load Analysis (ELA) and Spectral Fatigue Analysis (SFA) provide for a fully integrated solution to the complex challenge of developing lifetime extreme loads for structural design of ships and other floating structures. The solution requires a seakeeping and wave loading analysis over the operational life of the ship and accurate mapping of the predicted hydrodynamic design loads to the finite element model for design analysis. The mapping task has proven to be a difficult problem to solve. Likewise, accurate, high-fidelity spectral fatigue analysis requires solving a large number of global finite element analyses for each combination of ship speed and heading in each incremental wave frequency in the ship's operating profile. This requires analyzing as many as 7200 load cases, caching the results, and post-processing element level stress Response Amplitude Operators (RAOs). Few high-fidelity solutions to this SFA problem exist worldwide, and accurate structural fatigue analysis is critical to designing a ship that will operate successfully through its planned service life.MAESTRO-Wave uses a unique approach to leveraging the wetted surface finite element model for the hydrodynamic surface grid. The hydrodynamic loads are also processed uniquely in MAESTRO-Wave to generate accurate and balanced hydro loads which avoid the more typical need for inertia relief to balance the finite element solution. MAESTRO-Wave is seamlessly integrated with the MAESTRO modeling and FEA environment, such that the structural engineer is fully capable of conducting the hydrodynamic analysis. The ELA module performs engineering searches to identify the critical conditions of ship speed, heading and sea state that generate the highest load conditions for the hull girder. These become the extreme lifetime loads for the structural design process. The webinar will summarize the basic technical approach of these software tools and describe their practical use by the ship design team.The presentation will conclude with a summary of future webinars on Prediction of Seaway Loads.ALL ARE WELCOME!SPEAKERS/PRESENTERSMing Ma, PhD and Professor Adrian S. OnasMing Ma, PhD, Partner, Technical Director, MAESTRO Marine LLC.Ming Ma earned his Ph. D. in ship structures from Virginia Tech in 1994. Dr. Ma is a partner and the Technical Director of MAESTRO Marine LLC, where he leads the development and technical support of the MAESTRO software and provides software development and naval architecture design services to shipbuilders, design firms and U.S. government agencies including NAVSEA, the U.S. Coast Guard and DARPA. His areas of expertise include ship structural software development, structural analysis, limit state evaluation, hydrodynamic loading analysis and structural optimization. Dr. Ma supports the use of MAESTRO by the U.S. Navy and other national navies and commercial design groups throughout the world for naval and commercial ships and craft.
Prof. Adrian S. Onas, Webb Institute
Dr. Onas is a Naval Architect with over 25 years of ship design, operation and research experience in the maritime industry and academia. His experience includes a 15-year career with DNV, followed by an on-going academic appointment as Professor of Naval Architecture and Director of the Circulating Water Channel at Webb Institute since 2011. Prof. Onas' interests include extreme events in nonlinear systems, theoretical and computational hydromechanics, transom stern hydrodynamics and innovative ship design. He is currently the Chair of the SNAME T&R Hydrodynamics Committee, within which he also leads the Seakeeping Characteristics Panel (H-07), and a member of the SNAME T&R Marine Forensics Committee. Dr. Onas holds a PhD in Ocean Engineering from Stevens Institute of Technology. His dissertation was titled "Nonlinear roll motions of a frigate-type trimaran and susceptibility to parametric roll resonance". Prof. Onas has an MS in Naval Architecture/Marine Engineering from University of New Orleans (1998) and a BS in Naval Engineering from the Romanian Naval Academy and Constanta Maritime University (1993). He is a Fellow of the Society of Naval Architects and Marine Engineers (SNAME), a Fellow of the Royal Institution of Naval Architects (RINA), a member of the International Hydrofoil Society (IHS) and SNAME Representative to the U.S. National Committee for Theoretical and Applied Mechanics (USNC/TAM) on behalf of the National Academies of Sciences, Engineering and Medicine (NASEM).