V.V. Sukhov – Dr.Sc.(Eng.), Head of Engineering Department, JSC «Concern «Morinsys-Agat» (Moscow)
The problems the resource of ship computing systems under external influences are considered. It is determined that all dependencies are complex systems of differential equations. It is shown that spread of durability indicators is the result of the following factors: random properties of the realization of external influence, while the operating conditions are characterized by fixed of the system parameters; the range of operating condition, which in turn may vary; variability of the properties of the product (or system) and its components. The above object are a set of systems of modules, the interaction of which can be described in the framework of the system theory of reliability. Complex systems, for example, computational, with similar ERE, emit a large of heat during operation. This leads to the need to use additional devices for forced cooling, which have their own properties of reliability and can provide for the reliability of the entire system.
The initial information for the design of devices (or systems) are the data on the materials included in the units and blocks, loads and operating conditions, requirements for the properties of reliability (failure-free, durability, maintainability and persistence), including the normative values of resource and service life. The purpose of forecasting is to predict the values of the turnaround resource, establish the dependence of these values on the initial data and indicate rational ways for matching the expected values of the resource with the normative values. Forecasting also includes a study of ways to manage the resource. Most of the information at the design stage is statistical in nature or very approximate. Based on the probabilistic-statistical concept, the missing information can be obtained from the probabilistic model, i.e. the initially selected distribution is updated when new information about the object is received.
When designing the equipment and the system as a whole, it is necessary to strive to reduce the resource dispersion when it is reached at its high values. The requirement for a small resource dispersion is also associated with the maintenance of products during operation. The large scatter of the resource causes problems with repair and maintenance, supply of spare parts. It is also associated not only with the physical and mechanical properties of materials or the quality of components, but also with the variability of operating conditions, variable loads and effects of a natural nature, which cannot be controlled and predicted. Therefore, resource scatter will occur, although sometimes it is possible to create two products that are the same.
Based on this, we can conclude that the durability at the present stage is important, which directly relates to the ship equipment in connection with the long-term operation (up to 30 years) of ships. The reason for the decline of one of the indicators of durability – a resource is physical aging, elements included in the equipment, which is caused by degradation processes. It is shown that the latter are provoked by destructive effects (loads) on the equipment (thermal cycles, long continuous operation, humidity, multiple power on/off, mechanical effects).
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