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Naval Architecture & Marine Engineering length of the sea conditions through which it is passing; and its speed must bear a certain relationship to both the wavelength and the vessel's natural rolling frequency. The 1998 incident and its severe cargo loss warranted a full investigation, the results of which opened the maritime industry's eyes to a long-standing prob- lem, the impact of which it had not yet fully appreciated. This investigation, which included model tests and numeri- cal simulations, determined that hulls with fine, underwater bodies coupled with wide, flat sterns and pronounced bow flare - typical of modern container- ships - may be susceptible to parametric roll. ABS began its own investigations into the causes and remedies for parametric roll. The two-year project has involved theoretical analyses and numerical sim- ulations, and included collaboration with Prof. J. Randolph Paulling, who in the 1970s first observed the paramet- ric roll phenomenon in model tests. "Shipowners would often approach me at conferences with nervous ques- An ABS research project deflates the mys- tique surrounding parametric roll, a rare but dangerous phenomenon particularly threatening to containerships. tions about parametric roll, asking why and how it happens." says Vadim Belenky, the engineer leading ABS' investigations into parametric roll. "Over time, I came to see that there is a kind of mystique and fear about this phenomenon," A ship motions specialist and former professor at the Kaliningrad University of Technology in Russia, Belenky is still an educator at heart and has dedicated himself to understanding and explaining the phenomenon. "The message I want to communicate to the industry is that there is no mystique to parametric roll. We at ABS understand the phenomenon very well and are tak- ing actions to help keep our clients safe from it." The Problem Parametric roll is a phenomenon that occurs in head or following seas, when a ship is traveling more or less perpendic- ularly to the wave front. The phenome- non was first recognized almost 50 years ago but, in the past, it was seen as affect- ing only smaller ships of poor stability in following seas. The development of Composites analysis Is inherently complex and challenging. Choosing the right FEA software provider becomes that much more important. Six years of experience with NEiNastran advanced software features coupled with superb service and support has confirmed my choice." Phi! Craven. America's Cup Composites Anolysi jm m Ms "" ;?.<• r -' 4L. - * • " A-2*. The top contenders^ iir'the America's Cub iise NEiNastran. lifiSft - 9* u i TU a 11« « .I The rest use something else.1 What software ajif i i**: 4 you using? / • THE CHALLENGE America's Cup yacht design is about pushing the envelope in performance. Here, marginal designs are quickly left behind. They finish in back with the rest of the pack...and sometimes not at all! THE SOLUTION NEiNastran users design, analyze and optimize their designs early in the development cycle. Noran Engineering technical support is there also to help them get the most out of structural, fluid dynamic and advanced composite modules. They get things right when it's time to build. They push the envelope...without breaking. THE OPPORTUNITY: "FREE COPY" Whether you're designing for the America's Cup or facing your own product development race, Noran Engineering can provide the design, analysis and simulation software that solves your problem and fits within your budget. We're so sure that you'll see the value in NEiNastran that we want you to use it free for 30 days. Experience the difference and compare the cost. www.NENastran.com/freecopy n Structural analysis of a composite mast ' JSSSL ^ ~ —* ' ' Customer DrtandoMuB ...Turning your ideas into reality with engineering software for analysis, design and simulation. Circle 285 on Reader Service Card • r Jy* 'jf- . v W . tfm Noran Engineering, Inc. 5555 Garden Grove Blvd., Ste 300 Westminster, CA 92683, USA Email: info@noraneng.com www.NENastran.com USA/Canada (877) - Nastran France (09) 241-5710 Germany (49) 0-8153-990-447 Italy (39) 0-574-404642 Scandanavia (46) 0-21-303-840 United Kingdom (44) 0-1438-791093 China (86) 10-8852-6939 India (91 >044-827-2688 Japan (81)8-2850-2210 South Korea (82) 02-2222-4081 November 2004 21
