# Summarization of Remaining Life Prediction Methods for Special Power Plants
## 2 Research Status at Home and Abroad
### State of Research on Dynamic Model-Driven RUL Prediction Methods  
Model-driven RUL prediction uses differential equations or difference equations to characterize the mapping relationship between mechanical equipment degradation processes and many degradation factors [28]. In classical models, physical quantities with practical significance such as stress, strain, fatigue damage, and energy are often used to characterize the degradation process of equipment. Experts and scholars at home and abroad have conducted a large number of studies on finite element model modification, rigid-flexible coupling analysis, the vibration characteristics of special beams, and the collision characteristics of multi-body structures [29; 30]. Finite element model correction technology has a high accuracy and meets the need to provide a guiding confidence degree for practical engineering practice. According to the widespread nonlinear characteristics in a real structure, an important research direction for future computational finite element models is to constantly revise the structural linear simplification of the computational model [31; 32]. Another key problem in dynamic analysis is the analysis of high displacement motion and flexible deformation for the computational model. At present, the analytical methods mainly include flexible modeling based on commercial dynamic analysis software [33; 34] and coordinate system method numerical calculation analysis [35; 36]. The combination of the two can better realize dynamic analysis. However, there is still significant room for improvement in terms of model refinement and computational efficiency. The research on the dynamic characteristics of special power plants mainly focuses on the analysis of the collision characteristics of multi-body structures and the vibration characteristics of special beams. Among these aspects, research on the collision characteristics of multi-body structures mainly focuses on material deformation characteristics, contact crash mechanic models, friction and wear morphology, and the optimization characteristics of characteristic structures. The research on material deformation characteristics and contact crash mechanic models is interrelated and influential. The deformation characteristics of materials include elasticity, plasticity, and the critical point of transition between the two stages of deformation [37]. There are many factors influencing this characteristic, such as the working state of the device, the microstructure of the material, and the processing technology of the material. The action characteristics of a specific material need to be obtained by combining experimental and theoretical analyses [38]. The contact crash mechanic model is a mathematical simulation of the contact crash process that can be achieved by fully understanding the deformation characteristics of materials. By obtaining initial parameters such as the elasticity damping mass, the contact crash process can be reasonably simulated, and important variables such as the force and displacement in the process can be obtained [39]. At present, the Lankarani-Nikravesh model and other spring-damping mass models are commonly used to simulate the contact crash process. Through theoretical analysis and simulation experiments, the contact crash process of special power plants can be well-recreated with a multi-cycle reciprocating motion [40]. At present, contact crash experiments are mostly simulation experiments, and the obtained test results are mostly indirect verification results. The lack of testing techniques for deriving theoretical analysis results and the actual physical phenomena that occur in the research process of special power plants using this analytical method are key research directions in this stage. Thestudy of friction and wear morphology should consider the impacts that the harsh working conditions within special power plants have on their specificity.