Мехатроника 1 Бөлім mechatronics
Reliability in the period of normal operation
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Мехатроника 1 том Баймухамедов М.Ф., Джаманбалин Қ.Қ.,Ақгул м.К.
| 5.4 Reliability in the period of normal operation
During the normal operation of mechatronic module gradual failures have not yet manifested and the reliability is characterized by a sudden failure. These failures are caused by the unfavorable confluence of many circumstances and therefore have a constant intensity, independent of duration of prior use of the product: λ(t) = λ = const, Where λ = 1/ m t – constant failure rate; m t – mean time to failure (usually in hours). Then λ , expressed by the number of failures per hour. In this case, the probability of failure-free operation: It obeys the exponential law of distribution of uptime. If, as usual, λ(t) ≤ 0,1, then P(t) ≈ 1 – λ(t) Density of distribution: Probabilities of failure-free operation depending on λ(t)t = 1 0,1 0,01 0,001 0,0001 P(t) = 0, 368 0,9 0,99 0,999 0,9999 So when = 1 probability P(t) = 0,368, then 63.2% of failures occur in time t < m t and only 36.8% later. To ensure a probability of failure-free operation of 0.9 or 0.99, only a small fraction of the average life span (0.1 or 0.01, respectively) can be used. If the work of the product occurs under different conditions, and then and the failure rates λ 1 (for the time t 1 ) and λ 2 (for the time t 2 ), then: 245 To determine the failure rate from experiments estimate the average opera- ting time to failure: where N is the total number of observations (products); t i – duration of the i -th time interval; K is the number of time intervals. Then The average number n of items that will fail to a given moment of time at λt ≤ 0.1: and the average number of N(p) items that will remain operational: N p ≈ N (1 – λt). жүктеу/скачать 11,25 Mb. Достарыңызбен бөлісу:
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