The Safety And Risk Assessment Of Mechanical And Structural Systems Considering Hybrid Uncertainty Quantification

To the complexity of the mechanical structure of the system, on the one hand, it reflects on the system performance, on the other hand, it reflects on the system application environment. Because of the complexity, the uncertainty phenomena are widespread in the mechanical structure system. In the case of random uncertainty, safety and risk evaluation method based on probability has increasingly mature; For the lack of knowledge, fuzzy and incomplete data, it causes cognitive uncertainty, and safety risk evaluation method based on possibility has showed a certain advantages; But for it contains both random and cognitive uncertainty, there are not a complete set of security risk assessment system and an optimization design method.In order to adapt to the mechanical structure of the system in the process of the safety and risk assessment model that exists low versatility, high computational complexity and realistic problems, in this paper, we put up the high-grade CNC machine tool and its key components as the main engineering background. In addition, combining with the probabilistic reliability and the reliability theory, we aim to explore a way to handle the hybrid uncertainty in the safety risk evaluation and optimization design process. It can provide a technical support for the reliability design of mechanical products. Then main research content of this article is as follows:(1) Without considering the application environment, to the cognitive uncertainty, based on Hilbert Hilbert space and interval analytic hierarchy process(IAHP) security risk evaluation method, we quantize the uncertainty evaluation indexes and ensure the risk grade. And such as the CNC system that we verify this method(2) Considering the environment, to the safety and risk assessment under the condition of hybrid uncertainty, numerical fitting and model validation method is used to determine the failure distribution function, and we can obtain a priori information. Combining with bayesian theory, we put forward the safety and risk assessment model. Analysing the typical CNC machine system, we verified the method that has good feasibility, and the system risk prediction of the mechanical structure is very practical.(3) In order to reveal the failure mode effectively under framework of the hybrid uncertainty, we adopt the test information and numerical simulation to quantize and margin(QMU) the performance parameters of key components. Combining with the V&V technology and the design experiment, we put forward a surrogate model, and study the expansion research of the QMU probability problem. To the performance parameters of the CNC machine, this method is proven that we could give out a reasonable evaluation and certification of the structure of the system based on the simple information.(4) To the hybrid uncertainty, combining with safety and reliability analysis method based on probability; in this paper we propose a hybrid uncertainty to structure reliability optimization design method. At the same time, sequence optimization and reliability evaluation can improve the computational efficiency. To the bolt of the pneumatic transmission system in the CNC machine structure, according to analysis, we proved that the method is feasible. And the uncomplete information affects the design results and the risk assessment.