Table 5 shows the value of parameters of each distribution that represents each set TTF data of diesel engines. It is seen that five out of seven set diesel engines TTF data are modeled using Weibull distribution either using two or three-parameter, while the other two are modeled using normal distribution.

Basically, the plotting of failure rate curve are plotted based upon equation (6). For a set of data that follows Weibull distribution, either two or three-parameter, equation (13) will be employed to plot he failure rate. While for a set of data that follows normal distribution, equation (6) is employed by counting the value of pdf and R(t) at certain time first.

Fig. 5, shows the comparison of failure rates of seven diesel engines plotting in a single curve plane. It can be seen that two diesel engines, they are HANSHIN/6LU28 and FUJI/6S32F, indicate a highly failure rate. These failure rates are relatively higher than those of other five diesel engines are. These two diesel engines can be categorized into wear-out region of widely known bath-up curve. Between these two diesel engines, HANSHlN/6LU28 has higher failure rate than that of FUJI/6S32F.

Taking out these two diesel engines, one will have five of analyzed diesel engines left and one can compare the failure rate among them. Fig. 6 shows the comparison of failure rates of seven diesel engines plotting in a single curve plane. We can see that three diesel engines already entered the wear-out region. They are OTSHUKA/50D6-29, LANG/SLD 315RPT, and DEUTZ/RBV 6M545, which has the failure rate from the highest one to the lowest one. The other two diesel engines, they are MAKITA/GNL H 6275 and NIIGATA/6M28, started to enter the wear-out period.

　

Fig. 5 Failure rates comparisom of seven diesel engines

Fig. 6 Failure rates comparison of five diesel engines

　

5.　CONCLUSIONS

　

This paper has discussed the failure rates analysis of seven different type diesel engines that have similar specification, that is the power delivered of each engine is 1000 HP. Among seven diesel engines analyzed, five of them have entered wear-out period while the other two stated to enter wear-out region.

Prior to the quantitative failure analysis, the qualitative analysis has also been performed. The analysis was performed by grouping the failures based upon the number their number of failures. Regular patterns were also obtained. Group 1 contains the upper parts of diesel engines. Group 2 consists of parts around the cylinders and pistons of the diesel engines, while group 3 covers lower parts of the diesel engines except for exhaust gas unit and camshaft.

This paper has revealed that most of diesel engines are in wear-out period, and replacing the existing diesel engines with the new ones is strongly recommended.

　

6. REFERENCES

　

　

Table 4 The value of MLE for each distribution tested

　

Table 5 The value of distribution parameters of each set data of TTF

　

　

　

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