The paperwork presents the way the reliability logic schemes could be used for modeling the reliability of the systems in the conditions the reliability models for their components are known. There is presented an application for a complex system of the vehicle, the breaking system, based on the normal or exponential identified models for the components reliability. The achieved results confirm the applicability of the proposed working method and highlight that this approach easily allows the forecast in an analytical way of the reliability of the complex systems.

The paper aims to identify a sufficiently precise and easy method that will ultimately lead to a working tool easily accessible and used for modeling reliability through the most widely used mathematical law in the field of reliability - the Weibull law. An analytical method for linearizing the Weibull function is proposed in order to allow, by using the linear regression function of the Microsoft Office software, to obtain the parameters of the reliability model. The calculation program created in Microsoft Excel allows the identification of the 3 parameters of the Weibull model and based on the Weibull model thus determined, the validation or invalidation of the reliability objectives. The application presented reveals that the proposed working tool is easy to use and the Weibull model obtained has a very good probability.

The reliability evaluation of an equipment is made through its functionality analysis in specific conditions. When these conditions are various, the accomplishment of functional requirements could be partial, not integral. In these cases, the reliability evaluation is realised through methods specific to systems with many stages, those based on the fuzzy logic being one of them. In this paperwork there are presented the most used algorithms for evaluation.