Analysis on the hull girder ultimate strength of a bulk carrier using simplified method based on an incremental-iterative approach

The hull girder ultimate strength of a typical bulk carrier is analyzed using a simplified method based on an incremental-iterative approach. First, vertical bending moment is examined by seven different methods. The moment versus curvature curves and the values of the ultimate longitudinal moments at collapse states are determined for both hogging and sagging cases. Second, the ultimate strength under coupled vertical and horizontal bending moment is accounted. An interaction curve is obtained, which corresponds to the results of series of calculation for the ship hull subject to bending conditions with different angles of curvature. It is found that the interaction curve is asymmetrical because the hull cross section is not symmetrical with respect to the horizontal axis and the structural response of the elements under compression is different from that under tension due to nonlinearity caused by buckling. The angles of the resultant bending moment vector and that of the curvature vector are different in investigated cases. The interaction design equations proposed by other researches are also addressed to discuss the results presented by this study

The evolution of fetal protection policies

This article examines the evolution of fetal protection policies (FPPs) by detailing their historical legacy and a range of contemporary social forces that have contributed to their maintenance. It is based on a case study of the 1977 U.S. Department of Labor, Occupational Safety and Health Administration (OSHA) hearings to revise the industrial lead standard, the 1991 U.S. Supreme Court decision that such policies are unconstitutional ( United Auto Workers v. Johnson Controls , 1991), and the case law preceding that decision. A primary issue is the notion that women and fetuses are disproportionately susceptible to lead. This study reveals the ways in which this belief is framed, disputed, and appropriated by various parties to the fetal protection policy debate. Implications of this case study for family health policy are also discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44656/1/10834_2006_Article_BF02353687.pd

Improving techniques for ship inspection and maintenance planning

A good inspection plan is crucial in order to detect defects in time and to make decisions about how quickly they must be repaired. Inspection planning may be based on experience (determined by class rules) which will, by default, treat all ships with the same inspection program or on first principal reliability-based methods. In the first case, only some of the knowledge that could be used to predict structural problems in case of ship-to-ship variation (construction or use) is gained from the data gathered. In the second case, reliability models (methods) can deal reasonably well with individual part but they do not give a good estimate of the overall reliability of the ship and they lack the 'experience database' that the experience-based, methodology uses so the reliability models are not calibrated by reality. This work will attempt to develop a method to calibrate the reliability models using the data from experience-based methods. The expected outcome of this work is a methodology to calibrate the reliability models, which will be produced as a report and as a computer program. The system, which will target the critical structural details in the ship, is intended to be used by the inspection companies, class surveyors, ship managers and ship designers and for the calibration of the inspection planning and reliability models as a decision support system tool to improve the safety of the ship and make inspections cost-effective. This research is funded by EU Project RlSPECT part of the 7th framework program

A new look at the effect of bandwidth and non-normality on fatigue damage

A new attempt is made in this paper to quantify the effect of bandwidth and non-normality in fatigue damage analysis. For the lack of actual stress history, a series of non-Gaussian and homogeneous random processes are generated with fast Fourier transform (FFT) acceleration. A factor is defined on the basis of rain-flow counting and Palmgren-Miner rule to correct the narrow band and normality assumption. It is revealed that the fatigue damage evaluated through the traditional method may be either conservative or rather unconservative. The upper and lower bounds of the correction factor are studied with respect to kurtosis and skewness of the generated random process and the slope of S-N curve