In the field of pressure vessel fatigue life, the study of fracture failure is very important. Based on the Paris law, the relation model between fatigue crack size and residual fatigue life is established by considering the circumferential stress. The relationship between the crack length and the crack depth is introduced. According to the specific structure of the pressure vessel, the relationship model between the fatigue crack size and the residual strength is established based on the residual strength allowable value. The S-N curve of pressure vessel is obtained based on two models. The fatigue life of the pressure vessel is predicted combined with the actual test data. By comparing with the actual service life, the feasibility of the model is verified, which provides a new method for predicting the residual life of pressure vessels.
To predict the life of clutch friction plate, friction characteristics of the friction plate and the steel sheet assembly are analyzed in the full life cycle. A contact model of friction surface is built based on micro-convex body model. Wear mathematical models of friction plate are established respectively based on the contact model and sliding work model. The wear results of the two models are compared and analyzed. The effect of temperature on wear is considered. Fatigue life of the friction plate is predicted by wear mathematical model according to the actual working conditions. The accuracy of the contact model and the influence degree of temperature on the wear are determined through comparative analysis of each prediction result.
Estimation of battery state and parameters play an important role in electric vehicle battery management system (BMS). Second-order RC model is applied, the initial parameters of battery model are determined by experiments. Data points of open circuit voltage and state of charge (OCV-SOC) are determined by experiment. Different function forms are used to fit the OCV-SOC discrete points, and the function form with great fitting effect is selected as the OCV-SOC fitting form. Dual extended Kalman filter which is divided into Parameter filter and state filter is applied. Battery state in state filter is a fast-time-varying parameter, The battery model parameters in parameter filter are divided into two parts. the battery model parameters are classified according to the influence of each parameter on the terminal voltage. A longer sampling time is applied to the parameters that have a strong impact on the terminal voltage, and a longest sampling time is applied to the parameters that have a weak impact on the terminal voltage. The time-scale classification method is validated both quantitatively and qualitatively. Compared with the previous methods, the three-time-scale classification method can reduce the number of parameter updates.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.