Research On Vibration Characteristics And Suppression Methods Of Cable-stayed Bridge Cable-beam-nonlinear Energy Sink Mode

In view of the objective background of transportation energy consumption,automobile energy-saving technology has been developed vigorously.Among them,energy vehicles（EVs）as new transportation tools are in a rapid development period in our country and the world.The high specific energy power battery represented by lithium-ion battery is the core energy storage component that drives the "power heart" of EVs.It is often accompanied by thermal runaway,the outstanding problems faced by thermal management technology and thermal safety protection system need to be further improved.And develop an efficient and reliable battery thermal management system（BTMS）,so as to effectively control the working temperature of the battery module.This is the urgent focus right now.Therefore,this paper is based on the heat generation theory of lithium-ion battery.Combined with numerical simulation and relevant experimental verification,the optimization design method of active and passive thermal management system is further proposed.Also,the evolutional law of heat transfer and temperature control performance are revealed under multi-scenario conditions.The main research contents and conclusions are as follows:（1）The 20 Ah LiFePO₄ lithium-ion prismatic battery is used for research,an equivalent substitution method is adopted to construct a battery thermodynamic model based on Bernadi ’s heat generation theory.And the model is checked and error analysis.Meanwhile,relying on thermal imaging and temperature sensing technology,the evolution laws of the local temperature rise characteristics and capacity characteristics of lithium-ion batteries are explored.（2）The thermal flow field characterization method based on the field synergy principle explores the pressure diodicity of the "Tesla valve" heat conduction element.A design method for an active irreversible liquid cooling system is further proposed.And the thermal and hydraulic performance of the typical liquid cooling system is compared and analyzed by combining numerical simulation and experimental means.It is found that reverse direction of the MSTV channel is compared with linear channel and forward direction of the MSTV channel.Its temperature gradient decreased by15.3% and 21.4%,respectively.And the maximum temperature decreased by 4.8℃ and6.5℃,respectively.But the reverse direction of the MSTV channel needs to provide greater pump power consumption（?P=437.4 Pa）.（3）To solve the problem that the active irreversible liquid cooling method cannot realize the rapid recovery of fluid working medium.An active reversible double-layer tree-like channel liquid cooling system is designed based on fractal theory.At the same time,it is optimized that the influence of different tree-like structure parameters on the operating temperature of liquid cooling system and pump power consumption by Murray’s law.Finally,combined with numerical simulation and design of experiment（DOE）methods,the structural configuration parameters dominated by the optimal performance of the liquid cooling system are formed.It is found that the maximum pump power consumption is only 181.75 Pa,compared with the active irreversible（serpentine channel）liquid cooling system.Therefore,the reversible liquid cooling system can not only meet the temperature control performance requirements of the battery module,but also provide low energy consumption driving capability.（4）Solid-liquid variable medium enhanced heat transfer is another important branch of temperature control research in active and passive thermal management systems.To overcome the problems of high liquid overflow and low latent heat of phase change materials（PCMs）,this paper uses encapsulated n-octadecane phase change microcapsules as the main matrix material.Composite phase change material specimens（MPCM/EG/HDPE）with different ratios are prepared by melt blendinghigh temperature hot pressing sintering molding method.Finally,the microstructure and thermal characteristics of the composite PCMs are analyzed by means of modern experimental instrument analysis.It is found that the proportion of the phase change component matrix material is within a certain range,the resisted heat leakage temperature is 807℃.The EG content increased to 25wt%,the solidification endothermic peak temperature remained at 32.1-34.4℃.And the peak melting temperature decreases to 42.3℃.This phase change temperature threshold can effectively improve the working performance of the battery module.（5）Based on the above research of active and passive battery thermal management system,NCA 21700 cylindrical lithium-ion battery is taken as the research object,and solved by numerical simulation and algorithm optimization.The thermal control method of active indirect liquid-cooled coupled passive phase change medium hybrid thermal management system（MP-BTMS）is studied.And explore the performance comparison between MP-BTMS and traditional thermal management system（SPBTMS）in multiple scenarios.It is found that the battery module is deeply discharged at a large rate,the maximum temperature of MP-BTMS could be 39.53°C,and the surface temperature deviation of the battery module is 2.6°C.Compared with SPBTMS,the total energy consumption of MP-BTMS decreased by 79.9%.Especially under extreme conditions（-10℃）,its holding time is 229.3% higher than that of SPBTMS.In summary,the active and passive thermal management system（including active reversible liquid cooling,irreversible liquid cooling and passive phase change medium enhanced heat transfer subsystem）are studied by combining experimental and numerical simulation methods.The research results and method can meet the multiple functional requirements of lithium-ion battery,such as heat dissipation,temperature equalization and preheating.It is of great significance to further promote the long-term development and application of EVs.