Study & Development Of The System On Life Forecasting And Risk Assessment For Propulsion Plants Of Ship

Modern ship is a big system engineering. With the development of science technology and manufacturing level for industry, the ship added many elements so that the whole system complexed,the equipment and propulsion plants of ship had a tendency to automation.Moreover,because of the development of large-scale and all-purpose, the cost increased largely. On the economy of work, if the ship hadn't worked for a day, large wealth would be lost and the breakdown would cause some person to die propbably. So the reliability was given a higher demand. As the center of ship-propulsion plants, it will affect the reliability and security of ship directly. The paper, taking propulsion plants of ship as object, inquires into the life forecasting of system reliability, analysises whether repair is difficult or easy, is economic or not, is effective or not, studies the risk assessment of fault. According to this, we developed a system of life forecasting and risk assessment.The paper analysises and calculates the reliability of system according to reliable diagram. We can make use of approximate integral in the method of Simpson to get the MTBF of system. Then we can gain the curve with time. According to the fact, we can give a minimal value of MTBF. When one value is smaller than the minimality, the relevant time may be thought of the theoretical lifetime of system.The paper sums up all kind of characters of repair-ability to shipping mechanism, for example complexity of structure, reachiability, check-ability, the ensure degree of Spares, the possession and quality of using and defense on documents, the degree of worker's skill and practice and so on. Taking advantage of Analytic Hierarchy Process and the result of bedding assessed by expert on all indexes, we can calculate the proportion. As long as we select the concrete content of all indexes at the time of repairing, we can assess whether repair is difficult or easy. Aiming at one repair plan and making use of the method of NPW ,We can judge whether repair is economic or not. There are some characters that aren't indicated by income and expenses directly, but the characters affect the system effect, for example noise, vibration, start, operation, convenience and so on. Making use of the method of, we can determine whetherrepair is effective or not. At last, we put together the two aspects for synthetic assessment.The paper uses QRA (Quantitative Risk Assessment) to assessing propulsion plants of ship and analysises the breakdown risk on propulsion plants of ship for determining the influent aspects to risk, so that we can gain larger safety reliability at the cost of small investment, avoid to loss the unnecessary money and person.At last, we developed a system of life forecasting and risk assessment using Powerbuilder7.0.The system can calculate the reliability, MTBF and forecast the reliable lifetime. So it gives a basis for design and decision; Moreover, the system can determine whether repair is difficult or easy, is economic or not, is effective or not; Thirdly, the system can draw FTA and ETA, get the minimal cut-assembly, calculate quantitativly, analysis the result of breakdown.