Considering the evolution of mechanical system parameters
and based on the continuous-time model and Ito Lemma
a time-varying reliability calculation model of multi-parameter complex mechanical system is established. In this model the systems' time-varying uncertainty can be expressed by drift functions and volatility functions
which are dependent on the drift rate and volatility rate known from basic design parameters. Thus the principle of evolution-based uncertainty design(EBUD)for complex mechanical systems is expounded. Compared with the traditional methods
this method can be applied to either the evolution-based uncertainty design of the elements(or subsystems)
or the uncertainty design for complex mechanical systems by establishing uniform system state equations. By thi
s means
the dynamic system reliability can be obtained
and the reliability at any time in the future can be calculated. Thereby the time-varying reliability calculation model can forecast the system's future development trend and offer early warnings
giving proper advice for the equipment maintenance. Taking the design of bolt group as an example and with the model applied
the time-varying reliabilities of screws in different positions are calculated and compared. In this example
the basic time-varying parameters include the turning torque M
the pre-load F
p
the minor diameter d
1
and the yield strength [S
]
of the screws. This method can also be used in other fields
such as evolution-based uncertainty design and reliability analysis of urban traffic control system
urban water-supply and drainage system
urban gas supply system
and so on.
关键词
Keywords
references
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