Lloyd's Register Research Articles

Design method for steel deck plates under quasi-static patch loads with allowable plastic deformations

Plastic deformation of plates in steel deck structures under heavy vehicle or helicopter wheel loads is common in ships and offshore structures, and is therefore of significant interest to designers of ro-ro/cargo ships, helicopter-carrying ships and offshore platforms. To provide insight into the plastic deformation of plates, the nonlinear elasto-plastic response of stiffened steel plates loaded quasi-statically by a central rigid rectangular indenter is investigated both experimentally and numerically. The numerically-determined stiffened plate permanent deflections compare well with those obtained experimentally. The concept of applying the elasto-plastic method to the design of deck plates under wheel patch loads is introduced, and the design principle of wheel patch loaded plating is studied together with the design criteria. A simple design formula to determine plating thickness is proposed based on an acceptable level of permanent set. Ship-mounted helideck plating design cases are given to illustrate the elasto-plastic method, and comparisons are made between the thicknesses derived using the proposed design formula and those found from Lloyd's Register (LR), Bureau Veritas (BV) and DNV-GL rule requirements.

Monitoring and modeling of environmental load considering dependence and its impact on the failure probability

Extreme weather conditions put heavy environmental loads on systems and may cause catastrophic failure. Classification societies such as Lloyd's Register, DNV GL and the American Bureau of Shipping recommend methods for environmental load calculations. These methods do not consider dependencies among parameters when calculating environmental loads. This paper proposes a novel methodology to consider the copula-based bivariate failure function to evaluate the dependence structure of parameters and minimize uncertainty in load calculations. It also presents a robust operational failure assessment model that considers real-time environmental parameters along with their dependencies. The proposed methodology and models are tested on a semi-submersible mobile unit (SMU). The failure probability corresponding to the wind and wave loads imposed on the SMU is calculated using a physical reliability model and Bayesian network. The copula-based bivariate failure function defines the dependence using the parameters δ, which are estimated using maximum likelihood estimation. A detailed case study illustrates the advantage of the proposed methodology. The proposed method is of vital significance to developing a safe operating envelope for offshore assets likely to face extreme weather conditions.

The impacts of risk level based on PSC inspection deficiencies on ship accident consequences

Global economic growth has stimulated the growth of international trade, leading to more maritime transport activities. However, in a complex and high-risk environment at sea, heavy ship accidents are difficult to eliminate. In order to prevent ship accidents more effectively, this study constructs a Bayesian network model to investigate the impact of various factors on the ship's risk level and accident consequences. To improve the reliability of the model, it proposes two hidden variables, the ship risk level and the PSC inspection level, to the model. The risk level variable represents the overall risk status of a ship. The PSC inspection level variable is used to aggregate complex PSC inspection results. Through analysis, it can not only identify the key factors affecting ship risk level, but also analyze the impact of the risk level on the consequences of the accident. The data used in this study is obtained from three databases, Lloyd's Register of Shipping (LR), International Maritime Organization (IMO) and Tokyo Memorandum (MoU). The model structure is learned through the Greedy thick thinning (GTT) algorithm, and it is evaluated using K-fold cross validation, log-likelihood function (LL), and Akaike Information Criterion (AIC). It also uses an overall sensitivity analysis to verify the validity of the model. The results of the model show that ship age, ship type and the PSC inspection level have the most significant impact on ship risk level. It also validates the effectiveness of PSC inspections on accident prevention.

Preliminary assessment of the design requirement against blast load for ship superstructure

ABSTRACT This paper attempts to rationalise, and assess, the existing design requirement for the sizing of the outer plating of a ship superstructure against an external air blast. First, a review of the current design guideline, specifically on how the blast load parameters were specified by the Rules and Regulations of Lloyd's Register and the assumptions behind the use of the scantling equation, is provided by the way of a design case study. Next, a non-linear SDOF model that incorporates a new plastic membrane phase is developed in this paper, together with three-dimensional FE simulations, to model the large inelastic deformation of the platings. The required plate thickness needed to resist a specified load intensity is then compared for the three different methods, viz. Lloyd's Register design rule, SDOF and FE. As expected, it will be shown that existing design guideline achieves the purpose of maintaining water or gas-tight integrity of a plating; however, there exists significant unnecessary redundancies (or over design) with implications on light-weighting. Additionally, the results will be summarised in the form of a failure map that will be useful to designers.

Announcement on New Awards - Lloyd Register Electrical and Electronic Engineering Prize & Shunichi Hayashi Prize (Outstanding Graduate Student Encouragement Prize)

Announcement on New Awards - Lloyd Register Electrical and Electronic Engineering Prize & Shunichi Hayashi Prize (Outstanding Graduate Student Encouragement Prize)

Stress concentration factors in FRP-strengthened offshore steel tubular T-joints under various brace loadings

The stress concentration factors (SCF) in FRP strengthened tubular T-joints subjected to brace axial loading, in-plane and out-of-plane bending moments were investigated. The numerical analyses were performed using ABAQUS Finite Element software package. The benchmark joints were validated against the Lloyd's Register and API equations together with the experimental results. Six different types of FRP materials such as Glass/Vinyl ester, Glass/Epoxy (Scotch ply 1002), S-Glass/Epoxy, Aramid/Epoxy (Kevlar 49/Epoxy), Carbon/Epoxy (T300-5208) and Carbon/Epoxy (AS/3501) were used as strengthening material in order to investigate the SCF values on the chord member of the tubular T-joints. Results derived from analyses are promising and show that the FRP strengthening method could be considered as an effective method to reduce the SCFs and consequently extend the fatigue life cycle of tubular T-joints. Results of the analyses for a 6 mm CFRP layup show that under axial loading (AX), the FRP strengthening decreases SCFs up to 30% and 50% at Crown and Saddle points on the chord, respectively. Moreover, under the action of in-plane bending (IPB) and out-of-plane bending (OPB) moments, SCF reductions of about 45% and 50% were observed, respectively.

Crew and passenger deaths from vessel accidents in United Kingdom passenger ships since 1900.

There is very limited systematic analysis of the causes and consequences of maritime accidents across the whole passenger sector during the twentieth century either in United Kingdom (UK) or in other maritime nations, but some of the larger events have been the subject of detailed investigations that led to improved safety measures. In recent years, there has been increased attention to the analysis of passenger ship accidents, especially in relation to the two now dominant markets: vehicle/passenger ferries and cruise ships. Long-term trends since 1900 in passenger and crew deaths on UK seagoing pas- senger ships that have sustained a maritime accident, as defined by Lloyds Register, have been collated and analysed. Over the course of the 20th century, there has been a continuous fall in the number of incidents and in their severity. This may be a reflection of improved vessel safety, however the scale and nature of UK passenger shipping has also changed markedly over the period. In addition to the reducing frequency of deaths it is apparent that the majority of fatalities in both crew and passengers came from a very small number of major events during the study period. Altho- ugh there has been no major disaster involving a UK passenger ship in the last 30 years, major casualties with heavy loss of life continue in the world passenger fleet, in recent years involving flags such as Greece, Indonesia, Italy, Panama and The Philippines.

Balancing a Destroyer on a Wave for Strength and Stability

A wave-balancing approach, where a ship is hydrostatically balanced on a wave with either the crest or the trough at midship, is often used to assess the inherent strength and stability of the vessel in waves. This work examines the differences between the wave types (sinusoidal and trochoidal) as well as the values of wave length, wave height, and position of the crest along the ship, with the goal of looking for the worst-case conditions for both intact stability and longitudinal strength. A notional destroyer is used as a case study to look at the trends in strength and stability in the upright condition and at angles of heel in waves. The notional destroyer is intentionally similar to but not the same as any existing design. The study shows that looking at a wider set of wave conditions and ship states can identify more extreme wave loading and stability degradation, suggesting that this more detailed analysis would be beneficial as a standard practice. 1. Introduction Both stability and longitudinal strength are key factors in a successful ship design. In both cases, it has long been recognized that the hydrostatic and hydrodynamic effects of waves are fundamentally important. Before the advent of computers and modern numerical models and methods, naval architects relied on hydrostatic analysis to determine the stability and strength characteristics of a given vessel. They typically added safety margins to account for other influences including wave dynamics. Some, however, used the method of "balancing a ship on a wave" to partially account for the influence of waves. In this methodology, the vessel was hydrostatically balanced on the crest or in the trough of a wave. The method was used first for finding bending moments, and later some experts used the method for assessing the stability of a ship. Although the method does not account for the dynamics of ship motion or hull loading transients, it is still used as a design tool today and is embedded in standards for strength (Lloyd's Register, NSR 2012) and stability (BV 1030-1 2012). It does give a "snapshot" of the hydrostatic forces and moments for a particular condition.

Sandwich Core Material Development for Ship Deck Structure

Development of sandwich materials for ship structure is aimed mainly to reduce the ship light weight so that the ship payload increases. This paper addresses development of sandwich core material suitable for ship structure. The core materials were composed of synthetic resin and talc; percentages of talc by total weight investigated were 10%, 20%, 30%, and 40%. Laboratory tests stipulated by the Lloyd’s Register (LR) and Det Norske Veritas (DNV) were performed on the core materials. Moreover, sandwich plates consisted of steel faceplates and the core materials were tested using ASTM standards including tension, shear, and flexure tests. The sandwich plates were applied for designing car deck of a ro-ro ship. Analysis of the sandwich deck under design load utilizing finite element approach was carried out to select the best sandwich core materials developed in this study. It was observed that the sandwich panel deck composed of synthetic resin and core material with 40% talc was better than the others.

A Safety Management and Signaling System Integration Method for Communication-Based Train Control System

The safety and the correctness of signaling system not only relate to the safety and efficiency of the rail transit operation, but also link with the life safety of passengers. In order to guarantee the safety of a signaling system for metro, the safety certificate for the trial operation with carrying passengers must be obtained. In this paper, a suitable safety management and signaling system integration model are explored according to the CENELEC standards and applied in China. With taking account of the strict safety requirements for the Communication-Based Train Control (CBTC) system, a safety assurance and assessment method based on safety verification and validation process was put forward. This method was applied in every phase of the CBTC system development life cycle to monitor and control each activity in the life cycle and to review each document in system development process. At the same time, this method is also used to ensure the traceability of relevant documents and to test all the functions of the whole system sufficiently and completely. So that the safety operation of train control system can be ensured. Up to now, the independently developed CBTC system with the safety management had been applied in many urban rail transit lines of Beijing, such as Yizhuang Line, Changping Line, Line No. 14, and Line No. 7. The CBTC signaling systems of these projects have been authorized by the safety certification from a third party, e.g., Lloyd Register which is a British company and famous for the safety verification and validation process.

Design and Calibration of a Full Scale Active Magnetic Bearing Based Test Facility for Investigating Rotordynamic Properties of Turbomachinery Seals in Multiphase Flow

The recent move toward subsea oil and gas production brings about a requirement to locate process equipment in deepwater installations. Furthermore, there is a drive toward omitting well stream separation functionality, as this adds complexity and cost to the subsea installation. This in turn leads to technical challenges for the subsea installed pumps and compressors that are now required to handle multiphase flow of varying gas to liquid ratios. This highlights the necessity for a strong research focus on multiphase flow impact on rotordynamic properties and thereby operational stability of the subsea installed rotating machinery. It is well known that careful design of turbomachinery seals, such as interstage and balance piston seals, is pivotal for the performance of pumps and compressors. Consequently, the ability to predict the complex interaction between fluid dynamics and rotordynamics within these seals is key. Numerical tools offering predictive capabilities for turbomachinery seals in multiphase flow are currently being developed and refined, however the lack of experimental data for multiphase seals renders benchmarking and validation impossible. To this end, the Technical University of Denmark and Lloyd's Register Consulting are currently establishing a purpose built state of the art multiphase seal test facility, which is divided into three modules. Module I consists of a full scale active magnetic bearing (AMB) based rotordynamic test bench. The internally designed custom AMBs are equipped with an embedded Hall sensor system enabling high-precision noncontact seal force quantification. Module II is a fully automatized calibration facility for the Hall sensor based force quantification system. Module III consists of the test seal housing assembly. This paper provides details on the design of the novel test facility and the calibration of the Hall sensor system employed to measure AMB forces. Calibration and validation results are presented, along with an uncertainty analysis on the force quantification capabilities.

Lloyd's Register—Cyber CBM (Condition based maintenance)

Classification survey requirements are anchored on the concept of a periodic, time-based preventive maintenance regime. The underlying principle of the periodic maintenance philosophy is that parts and components of equipment, machinery, systems and structures eventually wear out, thus the safety and reliability of parts and components – indeed the entire vessel – are directly correlated with time and operational age. While development of techniques and technologies have continuously improved surveys and inspection, the periodic maintenance philosophy has been the de-facto standard in marine and offshore industries for many decades. This paper presents Lloyd Register’s Cyber condition based maintenance (CBM) technique: a scalable evaluation of components, equipment, machinery, systems and structures that detects their emergent faults, and characterises their progression to failure. This is an important step in the evolution of in-service classification:moving away from a periodic, time-based maintenance regime into an intelligent, real-time and predictive vessel health maintenance regime.

The Mermaid Atoll Shipwreck-A mysterious early 19th-century loss MYRA STANBURY with 16 Contributors 307 pp., including 9 appendices, 222 figs mostly colour, 46 tables Australian National Centre of Excellence for Maritime Archaeology and the Australasian I

The Mermaid Atoll Shipwreck-A mysterious early 19th-century loss MYRA STANBURY with 16 Contributors 307 pp., including 9 appendices, 222 figs mostly colour, 46 tables Australian National Centre of Excellence for Maritime Archaeology and the Australasian I

DES Prediction of Cavitation Erosion and Its Validation for a Ship Scale Propeller

Lloyd's Register Technical Investigation Department (LR TID) have developed numerical functions for the prediction of cavitation erosion aggressiveness within Computational Fluid Dynamics (CFD) simulations. These functions were previously validated for a model scale hydrofoil and ship scale rudder [1]. For the current study the functions were applied to a cargo ship's full scale propeller, on which the severe cavitation erosion was reported. The performed Detach Eddy Simulation (DES) required a fine computational mesh (approximately 22 million cells), together with a very small time step (2.0E-4 s). As the cavitation for this type of vessel is primarily caused by a highly non-uniform wake, the hull was also included in the simulation. The applied method under predicted the cavitation extent and did not fully resolve the tip vortex; however, the areas of cavitation collapse were captured successfully. Consequently, the developed functions showed a very good prediction of erosion areas, as confirmed by comparison with underwater propeller inspection results.

Measuring Britain's Merchant Shipbuilding Output in the Twentieth Century

This article reports on work done to arrive at a reliable estimate of British shipbuilding output in the twentieth century. Three datasets are considered: the annual figures of the Shipbuilding Conference, those of Lloyd's Register and those of the British Shipbuilding Database (BSD). Differences between the figures are explored and reconciliation attempted by examining the sources used by compilers of the datasets in order to arrive at what is believed to be the most accurate estimate yet attempted of British shipbuilding output in the twentieth century. The article is notable in that for the first time a table of completions has been compiled for the entire century.

Estimation methods for the steel weight of inland tank ships

In this paper, two methods to estimate the steel weight of inland coated tank ships during the earliest design stages are presented: the first is a set of simple functions that are valid for ships with common dimensions and length-to-beam ratios of European inland ships. The second is a single more elaborate function that covers a larger range of dimensions and length-to-beam ratios. Both methods are based on the calculated weights of a large series of computer-generated ship designs. To calculate these weights, a computer program was developed that generates ship structures on the basis of Lloyds Register's rules for inland ships and estimates the steel weight of those ship structures. The approach to generate the ship structures as well as a validation of their scantlings and steel weight are also discussed.

New Estimation Methods for the Steel Weight of European Inland Dry Bulk Ships

There are hardly any methods available for the estimation of the steel weight of inland ships in the earliest design stages. The few weight estimation methods that are available are out of date, limited to a narrow band of main dimensions and not sensitive enough to be used for innovative designs. In this article, which summarizes key results from the PhD thesis of Hekkenberg (2013), new methods are derived for the estimation of the steel weight of inland dry bulk ships. The estimation methods that are presented are derived from large systematic series of computer generated ship designs that comply with Lloyds Register's rules regarding their structure and with the European rules for freeboard. The structure and weight of these designs are validated by a comparison of modeled scantlings with the scantlings of midship sections of existing ships. Further validation is done by a comparison of the modeled overall steel weight with the steel weight of actual ships and the weight estimates of existing methods. The designs are used to derive two types of estimation methods: the first is a set of simple formulas that are valid for inland ships with common sizes and L/B ratios and the second is a more complex set of formulas that allows estimation of the steel weight of inland ships with draughts ranging from 1.5 to 4.5 m, lengths of 40–185 m, beams of 5–25 m, and L/B ratios of 4–20.

New Estimation Methods for the Steel Weight of European Inland Dry Bulk Ships

There are hardly any methods available for the estimation of the steel weight of inland ships in the earliest design stages. The few weight estimation methods that are available are out of date, limited to a narrow band of main dimensions and not sensitive enough to be used for innovative designs. In this article, which summarizes key results from the PhD thesis of Hekkenberg (2013), new methods are derived for the estimation of the steel weight of inland dry bulk ships. The estimation methods that are presented are derived from large systematic series of computer-generated ship designs that comply with Lloyds Register's rules regarding their structure and with the European rules for freeboard. The structure and weight of these designs are validated by a comparison of modeled scantlings with the scantlings of midship sections of existing ships. Further validation is done by a comparison of the modeled overall steel weight with the steel weight of actual ships and the weight estimates of existing methods. The designs are used to derive two types of estimation methods: the first is a set of simple formulas that are valid for inland ships with common sizes and L/B ratios and the second is a more complex set of formulas that allows estimation of the steel weight of inland ships with draughts ranging from 1.5 to 4.5 m, lengths of 40‐185 m, beams of 5‐25 m, and L/B ratios of 4‐20.

효율적인 철도안전관리 체계 구축에 관한 연구 - 한국철도공사 안전관리체계를 중심으로 -

Advanced Safety Management System(SMS) of Korea Railroad Corporation for risk management should be established applying contents-centered domestic standard according to Railway Safety Act and process-centered international standards suggested by Lloyd's Register Company. Besides, laws, regulations, guidelines and manuals which are optimized for each sector should be systematically integrated to strengthen the consistency of SMS of KORAIL. New safety regulations and guidelines for safety management/train operations/maintenance should be established according to the safety policy of KORAIL to boost effective field work by regulations, guidelines, manuals, etc. The advanced Safety Management System will lead KORAIL as a competent global enterprise with its boosted reputation in the international railway market.

EVALUATION OF NOₓ EMISSION AND DISPERSION FROM MARINE SHIPS IN KLAIPEDA SEA PORT

The aim of the presented research was to assess the NOx emission and dispersion from marine ships in Klaipeda sea port. NOx emissions from ships operating in Klaipeda sea port were calculated using the Lloyd's Register detailed ship movement method, after collecting the information about technical characteristics of each marine ship visiting the port and the time spent staying in the port. After calculating the emission, the modelling using AERMOD software was completed and the dispersion of pollutants over different seasons of the year was determined. When performing the evaluation of NOx emissions it was estimated, that most of these pollutants enter the atmosphere from stationary vessels moored to quays with active auxiliary motors; this accounts even for up to 72% of the total NOx emission from marine ships in Klaipeda port. It was calculated that a total of 945.6 tons of NOx compounds enter the air basin from ships which operate in Klaipeda port. It was determined that the seasonality and meteorological conditions are a significant factor affecting the dispersion of pollutants. During winter time, a higher dispersion of pollutants is typically found at the source of contamination, and in the summer pollutants are decomposed more quickly and their concentrations as formed above the port are 30% lower, however, 40-50% higher concentrations are formed over the Klaipeda city residential districts.