5 results about "Limit state function" patented technology

The invention discloses a time-varying reliability optimization design method and system for a helical gear. The method comprises the following steps: establishing a gear reliability optimization design model which takes gear volume minimization as an optimization target and takes full-life-cycle time-varying reliability as a constraint; constructing a gear contact fatigue time-varying limit state function coupling the time-varying load spectrum and the material strength degradation model; constructing a time-varying reliability analysis module based on an agent model and an active learning strategy so as to evaluate the time-varying limit state function; and an optimization algorithm is adopted to solve the gear reliability optimization design model, the time-varying failure probability of the candidate scheme is evaluated by calling the time-varying reliability analysis module, the time-varying reliability constraint is processed according to the time-varying failure probability, and optimal gear design parameters meeting the constraint are output. According to the method, efficient cooperation of time-varying reliability high-precision evaluation and lightweight optimization design is realized, and the problem that a time-varying factor cannot be considered in optimization due to too high analysis cost in a traditional method is solved.

The embodiment of the invention discloses a mode importance analysis method for a turbine blade in a fuzzy failure state, which comprises the following steps of: constructing a creep-fatigue life reliability analysis model of the turbine blade in the fuzzy failure state, introducing a one-dimensional standard normal variable, and fusing fuzziness of the failure state into a limit state function to form a generalized limit state function; a Kriging model of a generalized limit state function corresponding to each mode is updated by adopting a sequence, repeated training of the Kriging model is avoided, the utilization rate of a training sample is improved, the system reliability and the component reliability are analyzed respectively, and then mode importance analysis under a turbine blade fuzzy failure state is completed in combination with a mode importance index system. According to the analysis result, the importance sequence of the fatigue life reliability of each part of the turbine blade in the fuzzy failure state can be explored, the characteristics of key parts of the turbine blade in the fuzzy failure state can be identified, and a scientific and reasonable basis is provided for structural optimization and fault detection of the turbine blade.

The present invention discloses a method for calculating load and resistance partial factors, a storage medium, and a device, belonging to the field of ballastless tracks. By establishing a structural limit state function, simplifying it, and introducing an equivalent resistance attenuation coefficient g*, an empirical calculation formula for g* can be obtained through the derivation and simplification of the equivalent resistance attenuation coefficient. On this basis, by introducing the third-moment reliability theory, μ R0 , σ G0 , α 3G0 , β 2T0 , μ RT , σ G , α 3G , β 2T and other parameters can be obtained, and the calculation formula for load and resistance partial factors considering the degradation of structural resistance performance in the whole life cycle can be accurately constructed, and the acquisition of load and resistance analysis coefficients can be quickly realized. The method in the present invention is simple in method and convenient in operation, can fully consider the attenuation of the structural resistance performance of the design object, avoid the iterative calculation process in the existing design process, simplify the calculation process of reliability design, shorten the design cycle, improve the design efficiency, and has good practical value and practical significance.

The application discloses a kind of oblique-tooth cylindrical gear time-varying reliability optimization design method and system, the method includes: the gear reliability optimization design model of minimum volume of gear body is established as optimization goal, and time-varying reliability in whole life cycle is constraint;Coupling time-varying load spectrum and material strength degradation model is constructed gear contact fatigue time-varying limit state function;Time-varying reliability analysis module based on proxy model and active learning strategy is constructed to evaluate time-varying limit state function;Optimization algorithm is used to solve the gear reliability optimization design model, the time-varying failure probability of candidate scheme is evaluated by calling the time-varying reliability analysis module and accordingly the time-varying reliability constraint is processed, and the optimal gear design parameter meeting the constraint is output.The application realizes the efficient cooperation of high-precision evaluation and lightweight optimization design of time-varying reliability, solves the problem that traditional method cannot consider time-varying factor in optimization due to high analysis cost.

The present invention discloses a method, medium and equipment for directly calculating the load resistance partial coefficient based on the moment method, which belongs to the field of ballastless track. By establishing a structural limit state function and setting a corresponding calculation formula, the method can successively complete μ Rcheck 、μ G , σ G , α 3G , β 2Tcheck The calculation of parameters such as , and then the structural resistance design value μ can be calculated R , and on this basis complete the target second-order reliability index β 2T The method of direct calculation of load resistance partial coefficients based on the moment method of the present invention is simple and easy to calculate. It can quickly realize the direct calculation of structural resistance design value and load resistance partial coefficient, simplify the calculation process of engineering structure reliability design, avoid the iterative calculation process of the existing design process, shorten the reliability design cycle, improve the efficiency of reliability design, meet the actual needs of engineering applications, and have good practical value and realistic significance.