Aim. Calculations are an integral part of the development of any complex technical object. Normally, they are subdivided into the calculations to confirm product operability (kinematic, electrical, thermal, strength, hydraulic and pneumatic systems analysis, etc.) and calculations to confirm its dependability (calculation of reliability, longevity, maintainability, storability and other indicators). As it is understood and provided in statutory documents, dependability calculation involves procedures of identification of an object’s dependability indicators using methods based on their calculation using reference information on the object’s components dependability, on the dependability of analog objects, on the properties of the materials and other information available at the time of calculation. However, in the case of development of unique highly vital systems, obtaining statistical data for dependability calculation is impossible due to two conflicting conditions, i.e. the limited number of produced objects and the requirement of high accuracy of the input information. Nevertheless, in the author’s opinion dependability calculations must be performed. The only question is how to calculate the dependability and what such calculation should mean.Methods. In the classic dependability theory, the conventional understanding of probability of no-failure is the frequency of failures in time, yet for unique highly vital systems the failure rate must tend to zero over the entire period of operation (preferably, there should be no failures at all). For this reason the concept of “failure” in the context of unique highly vital systems should probably be interpreted not as an event, i.e. any fact, which as a result of experience can occur or not occur, but as possible risk, i.e. an undesirable situation or circumstance that is characterized by the probability of occurrence and potentially negative consequences. Then, an event in the form of a real or potential failure in operation can be associated with a risk in the form of probability of failure with negative consequences, which in terms of the consequences is equally unacceptable with regard to unique highly vital systems. In this case dependability calculation can be reasonably substituted with risk assessment, a process that encompasses risk identification, risk analysis and comparative risk assessment. Thus, risk assessment enables the achievement of the target dependability directly by substantiating the stability of manifestation of a specific product’s properties and not indirectly through undependability caused by failures of analog products.Results. The paper shows the procedure of risk assessment for unique highly vital systems. Using the example of a mechanical system with actuated parts represented by a spacecraft single-section pivoted rod the risk assessment procedures are shown. The feasibility of risk assessment with the use of design engineering analysis of dependability is demonstrated.Conclusions. It is shown that the absence of statistical data on the dependability of analogs of unique highly vital systems does not prevent dependability calculation in the form of risk assessment. Moreover, the results of such calculations can be a source and guidelines for adopting design and process engineering solutions in the development of products with target dependability indicators. However, legalizing the method of such calculations requires the modifications of the technical rules and regulations to allow for dependability calculation by other means than with the use of statistical data on the failures of analogs.

Aim. The paper examines the problems caused by the conventional interpretation of dependability that prevent the practical use of dependability analysis (assessment) as a tool for engineers involved in the creation of unique highly vital systems and substantiates proposals for their resolution. Methods. The paper analyzes the problem of quantitative estimation of the dependability of unique highly vital systems without the use of probability statistical models. The view of dependability as a physical property of a product (as a result of changes in its internal state) allows at the physical level ensuring lasting capability to fulfil the required functions and quantitatively estimating the criteria of the required functions’ performance, that can be defined by, for instance, specifying a set of parameters for each function that characterize the capability to perform, as well as the permissible limits of such parameters’ variation. Such approach causes the requirement to take the origin of dependability into consideration and examine the causes of unlikely failures that are to be identified by means of additional analysis in parallel with calculations and experiments performed to support dependability. The solution to the problems of fuzzy terminology allows revealing the interrelation between the quality and the dependability, thus enabling using the single information basis of design and process engineering solutions the analysis, synthesis and assessment of the dependability of unique highly vital systems based on performance parameters without the use of probabilistic statistical models. Results. The solution of the above dependability-related problems allows ensuring dependability based on the physicality (causal connections) and physical necessity (consistency with the laws of nature) of the causes of failures. The dependability of unique highly vital systems must be ensured from the very early lifecycle stages based on consecutive execution of certain design, process engineering and manufacturing procedures, as well as application of engineering and design analysis of dependability, which also allows solving problems indirectly related to dependability, e.g. improving the quality and reducing the cost of the manufactured products. Conciusions. The paper shows that the application of design engineering methods for the dependability analysis (assessment) allows within the framework of existing views, yet with certain corrections solving dependability-related problems without the use of the mathematics of the classic dependability theory. High dependability can be achieved by the same ways as undependability comes about, i.e. through design and process engineering solutions. The analysis, substantiation of engineering solutions and specification of necessary and sufficient requirements for the manufacturing process allows achieving the target dependability by engineering means through higher quality of design and process engineering. If we regard dependability as a multiparametric property, parametric models of products can be developed that enable the evaluation of the temporal stability of parameter values using methods of individual design dependability and/or design engineering analysis of dependability. The principles of unity of the design concept and its implementation in manufacture enables the development of products and assessment of their dependability based on a single foundation, i.e. the design and process engineering solutions directly associated with the capabilities of a specific manufacturing facility.

Успешность перехода на цифровые технологии проектирования и инжиниринга в условиях Индустрии 4.0 определяется не только совершенствованием технических и программновычислительных средств проектирования, но и эффективностью человеческой деятельности при их использовании. Одним из вызовов новой промышленной революции является необходимость повышения профессионального уровня проектанта и конструктора в области подготовки и верификации исходных данных на входе в компьютерную модель и валидации результатов его работы на выходе. Главным образом это касается наиболее трудоѐмких и ответственных работ по проектированию сложных изделий с малой вероятностью отказов. Результат может быть достигнут за счѐт применения новых методов конструкторско-технологического анализа для смягчения или исключения человеческих ошибок при принятии технических решений. Использование методов конструкторско-технологического анализа надѐжности не нарушает естественный ход процессов проектирования и конструирования, при этом обеспечивает обоснование параметров функционирования, которое необходимо для принятия конструкторских решений. Для этого используются методы анализа, позволяющие представить конструкторскую документацию в виде параметрической модели функционирования. Данная модель позволяет эмулировать аварийные ситуации при худших сочетаниях режимов и условий эксплуатации, что невозможно достичь при экспериментальной отработке. На основании такого моделирования принимаются обоснованные конструкторские решения, исключающие потенциальные отказы. Для исключения маловероятных отказов предусмотрена оригинальная опция, позволяющая устанавливать необходимые и достаточные требования в конструкторской документации для достижения бездефектного производства.Ключевые слова: Индустрия 4.0, цифровой двойник, цифровая тень, малая вероятность отказов, конструкторско-технологический анализ надѐжности.

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