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Technical and research (T&R) | Bulletins and reports
The results of midship bending stress measurements made on 22 ships of various types have been converted to a common bending moment coefficient, plotted and compared. Trends of wave bending moment with ship type 1 trade route, length and fullness are shown. Recommendations are made for future measurements, analysis and comparisons with model and analytical studies.
The concept of applying probabilistic methods to the structural design of ships and other marine structures has aroused a great deal of interest in some quarters and skepticism in others. Partial application of probability theory in recent years has already had a profound effect on standards of longitudinal strength, as found in classification society rules. At the same time, many of the doubts and questions felt by some designers may be the result of a lack of clear, simple explanations of a subject which at first appears to be complicated and baffling.
It has been more than fifteen years since the 1968 publication of the Bibliography on Ship Slamming. Over these years, interest in the topic has broadened and deepened as efforts continued toward the development of ships and other marine structures that possess ever better seakeeping and structural integrity characteristics. The HS-2 panel in pursuit of its mandate has tried to keep track of the developing literature on this subject and related areas of research and development. With the panel’s growing awareness of the increasing number of meaningful works that were available in the literature but not included in the earlier compilation, it was determined that a bibliography update would be timely and useful to the profession. The results of that determination are presented in the following which include all known references from 1965 forward to 1983 and not noted in the earlier work.
T&R Bulletin 2-29A: Measurement and Evaluation of Structural and Machinery Vibration in Ships (2004)
T&R Bulletin 2-29A together with the underlying ANSI documents supersedes the existing SNAME T&R Bulletins 2-25 and 2-29 and SNAME Codes C1, C4, and C5.
This Bulletin supplements ANSl documents S2.19, S2.25, S2.26,S2.27, S2.28 and S2.29 pertaining to ship vibration. The ANSl documents contain guidelines for the measurement and evaluation of structural and machinery vibration on ships. They also specify data acquisition and processing procedures which will result in consistent and reliable data to compare with the guidelines. However, the ANSl documents do not provide a lot of detail about how to make the vibration measurements or do the analytical calculations that are required.
"SLAMMING" damage sustained by the forward bottom structure of ships has been a consequential problem for over half a century; it has been a substantial contributor to the total cost of repair of hull damage to the U.S. Flagships. The Society of Naval Architects and Marine Engineers has a panel of its T&R organization studying the problem of ship slamming, its causes, and its effects. The work of researchers the world over are being reviewed and assimilated, the analyses and recommendations evaluated. It is appreciated by all that the problem of ship slamming has not yet been solved and is of such complexity, that it will most probably remain unsolved for some time into the future. However, much is now known about slamming and it is believed that it would be of service to the technical community if the Panel's Notes on Slamming were prepared in a form that could be of use in the future design of ships. By so doing, it is hoped that there will result in an order of magnitude reduction in the risk of forward bottom damage to ships, the short term goal for research on ship slamming.
The Notes are organized into five chapters which the Panel believes best reflects the major subdivisions of interest in the problem. The first chapter qualitatively describes the general problem, its history, and its consequences. The second and third chapters present hydrodynamic and structural aspects of slamming, giving both theoretical and experimental evaluations of various phenomena involved. Chapter four presents structural requirements for ship's forward bottoms as set down in the construction rules of several classification societies, while in chapter five, interim design methods are set down that the Panel believes will provide guidance for the development of more successful structural performance in ship forward bottoms.
The Notes are intended as an introduction to, and summary of, many developments and theories. It is not possible to fully discuss all the work on Ship Slamming in this document. It is anticipated that in those areas of particular interest, the reader will obtain original documents and determine the applicability, limitations, and assumptions of the work to their ship designs.
This bulletin was compiled by Dr. Dominique Béghin as Chapter 17 for the revised edition of the book Ship Structural Design, edited by Dr. Owen F. Hughes, and will ultimately be published in that form. It is released now as a T&R bulletin in order to make it available for use at an earlier date.
This bulletin was compiled by Dr. Dominique Beghin as Chapter 5 for the revised edition of the book Ship Structural Design, edited by Dr. Owen F. Hughes, and will ultimately be published in that form. It is released now as a T &R Bulletin in order to make it available for use at an earlier date.
The efficiency of a ship design and its structural integrity hinge upon the extent to which design loads adequately represent the corresponding true service loads expected. Historical methods employed to determine hull-girder design loads are not suitable for the design of many of the newer types of surface ships that continue to be proposed.
A new way of model testing in waves was developed that includes at the same time the measurement of ship motions, wave loads (both ordinary wave induced and hydrodynamic impact), and the ship structural response. This approach became possible partially by evolving model testing techniques over the years, but especially through newly developed testing techniques, instrumentation, and data collection systems for this type of testing. This report documents these model testing techniques and provides a reference point for future testing and innovation in the field.
Development of this new far more accurate approach to measuring ship motions and wave loads required extensive collaborative discussion and speculation by previously separate and distinct technologies and practitioners and involved the close working relationships between T&R Panels HS-1 (Hull Loading) and HS-2 (Impact Loading & Response) with subsequent reviews by Panel H-7 (Seakeeping).
This T&R Bulletin provides a unique and practical guide to materials engineering for the maritime industry. It covers aspects of materials engineering, testing and evaluation, corrosion, and failure that are of specific interest to marine designers as well as those who maintain structure and machinery in the marine environment. The guide also provides information on the non-destructive test and evaluation techniques and their use and addresses advanced materials and processes. Additional references are provided to assist those who require more detailed information on a specific process.
Part I of this Bulletin lists each research project report to The Society of Naval Architects and Marine Engineers in response to its inquiry to industry requesting information on projects concerned with the design, development, construction, and use of ships' machinery. Where the statement is made that "results are of a proprietary nature," "tests are..." "details are ... ",etc., it should not be construed that information is not available. In general, the correspondent may discuss the project with qualified inquirers on the basis of an exchange of information; or may discuss results, methods, details, etc., depending upon the nature of the inquiry and the inquirer.
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