As the 2nd report, we present a practical calculation method for torsional vibration of highly damped system with rubber couplings. This calculation system, constructed by a modal analysis technique, outputs frequency response characteristics, forced vibration responses, and mode animations.
In respect of a damping model and calculation accuracy, it was verified that the assumption of general viscous damping, employed in this calculation, give the satisfactory results close to measured ones.

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There are two types of manipulations of electrodes in arc welding such as stringer bead and weaving bead. The latter is widely used to reduce the number of weld passes, since it can place much deposited metal with one pass of welding bead. It is considered that the welding operation using weaving bead decreases the welding speed because the welding arc moves right and left while travelling in the direction of weld seam, and that the weld zone would be cooled more slowly than that welded by stringer baed. In this paper, the cooling process of weld zone with weaving bead is quantitatively evaluated by three dimensional finite difference method in the transient temperature field. The effects of weaving bead on the cooling cycle are compared with those by stringer bead. The validity of the numerical approach proposed here is ascertained by executing shielded metal arc welding by an expert worker.

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In case of analyzing the reliability data, we should consider that some different condition like a building age, technical skill, quality of material, sea condition, atmosphere condition and fuel oil quality. Diesel ship's relability is increasing due to set up mechatronic system in these years. But it can say that mechatronics system is increasing the failure rate caused by itselves. We analyzed about alarm rate of 47 modernized M0 ships and these summary as follows. Total alarm rates are 11. 1 cases per a month in 1981 to 1988, and it mean that an alarm occurred once per 3 days. Alarm rates of auxiliary equipment and auxiliary boiler system are over the average. Alarm rates of main engine system are closed to the average, but other rates are positioned in lower rate zone. The following items are requsted to increase reliability in future, but alarm rates of them are high level. They are boiler miss firing, L0 purifier abnormal leakage, C fuel oil purifier abnormal leakage, C fuel oil purifier abnormal leakage, bilge well high level, distillateplant high saliniity, bilge pump long running, M/E exhaust gas high temperature and soot-blow off system abnormal. Heavy failure occurred about 2% of total alarms, this failure occurred each 3500 hrs and system abnormal time is 87 minutes per case. But system abnormal time without alarm is 134 minutes per case. In comparison between the item number of alarm and alarmless (alarm rate is less than 8 year), the former items are 128 (62%) and the latter items are 80 (38%) . Therefore we can make reducing the measuring points due to change the setting position of them and to use the another equipment or to have additional cycle check in engine room.

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