In the measurement of damping material's dynamic mechanical performance(DMP) using flexural resonating cantilever beam method,the specimen's adhesive characteristic influences the test precision and accuracy. ...In the measurement of damping material's dynamic mechanical performance(DMP) using flexural resonating cantilever beam method,the specimen's adhesive characteristic influences the test precision and accuracy. Taking its effect into account,the improved measurement equations based on the resonance method are presented. The simulated results show that,for the sake of weakening the adhesive's influence on the measured results,the adhesive should be spreaded as thin as possible when specimen is prepared,the adhesive's density and loss factor should be selected as small as possible also,and its Young's modulus should be selected according to the damping material being measured;the same adhesion condition effects differently on the test results of different damping materials,i.e. the error due to the adhesive is more inconspicuous if the damping layer has bigger thickness,modulus,loss factor and a certain density according to the damping material being measured. These conclusions provide theoretical basis for selecting adhesive,improving adhesion technology,and designing specimen.展开更多
The propagation characteristics of laser-generated like-Rayleigh waves in viscoelastic adhesive coating/substrate structures were studied.Considering the viscoelasticity of the coating and substrate,we have establishe...The propagation characteristics of laser-generated like-Rayleigh waves in viscoelastic adhesive coating/substrate structures were studied.Considering the viscoelasticity of the coating and substrate,we have established the finite element models in frequency domain for the laser-generated like-Rayleigh waves in the epoxy coating/aluminum substrate,epoxy coating/brass substrate,and epoxy coating/foam substrate structures,respectively.In addition,we have investigated the waveform and propagation characteristics of the like-Rayleigh waves and studied the influences of the coating transparency,coating thickness,coating viscoelasticity,and substrate viscoelasticity on the propagation characteristics of the like-Rayleigh waves.Moreover,we have verified the results by the theoretical phase velocity and attenuation curves.The results show that the coating viscoelasticity induces the attenuation characteristics of the higher frequencies of the like-Rayleigh waves,but has little effect on the lower frequencies,and the substrate viscoelasticity has the influences on both the higher and lower frequencies of the like-Rayleigh waves,especially the lower frequencies.Furthermore,the mode and dispersive characteristics of the like-Rayleigh waves are closely related to the substrates.This study provides a useful theoretical basis for inverting mechanical parameters and evaluating the adhesive quality of the viscoelastic adhesive coating/substrate structures.展开更多
The adhesion of carbon particles on the surface of epoxy resin in insulating oil is a significant factor contributing to surface flashover.However,there is currently a lack of a dynamic model that can reasonably expla...The adhesion of carbon particles on the surface of epoxy resin in insulating oil is a significant factor contributing to surface flashover.However,there is currently a lack of a dynamic model that can reasonably explain the adhesion process of impurity particles,and the characteristics of particle adhesion are not yet clear,making it difficult to assess the risks of insulation contamination and surface flashover of valve-side bushing capacitance core.In this study,based on the Johnson-Kendall-Roberts(JKR)theory and the normal distribution characteristics of particle charges,the adhesion probability model of conductive particles in insulating oil on the surface of epoxy resin under DC electric fields was established,and carbon particle adhesion experiments were conducted to verify the accuracy of the model.The impact of electric field intensity,particle size,particle charge,and surface energy of the insulation material on the adhesion characteristics of carbon particles was investigated using the proposed model.The results can be utilised for the assessment of insulation contamination risks of valve-side bushing capacitance core and serves as a vital theoretical foundation for guiding the optimisation of anticontamination structures in internal insulation and the development of advanced pollution-resistant and flashover-resistant insulation materials.展开更多
基金Sponsored by the New Century Excellent Talent Project(NCET-06-0883)
文摘In the measurement of damping material's dynamic mechanical performance(DMP) using flexural resonating cantilever beam method,the specimen's adhesive characteristic influences the test precision and accuracy. Taking its effect into account,the improved measurement equations based on the resonance method are presented. The simulated results show that,for the sake of weakening the adhesive's influence on the measured results,the adhesive should be spreaded as thin as possible when specimen is prepared,the adhesive's density and loss factor should be selected as small as possible also,and its Young's modulus should be selected according to the damping material being measured;the same adhesion condition effects differently on the test results of different damping materials,i.e. the error due to the adhesive is more inconspicuous if the damping layer has bigger thickness,modulus,loss factor and a certain density according to the damping material being measured. These conclusions provide theoretical basis for selecting adhesive,improving adhesion technology,and designing specimen.
基金supported by National Basic Research Program of China(2012CB921504)Major Program of National Natural Science Foundation of China(51239005)+4 种基金National Natural Science Foundation of China(11404147,11174142)Natural Science Foundation of Jiangsu Province(BK20140519)China Postdoctoral Science Foundation(2015M571672)Research Fund for Advanced Talents of Jiangsu University(11JDG118)Training Project of Young Backbone Teachers of Jiangsu University
文摘The propagation characteristics of laser-generated like-Rayleigh waves in viscoelastic adhesive coating/substrate structures were studied.Considering the viscoelasticity of the coating and substrate,we have established the finite element models in frequency domain for the laser-generated like-Rayleigh waves in the epoxy coating/aluminum substrate,epoxy coating/brass substrate,and epoxy coating/foam substrate structures,respectively.In addition,we have investigated the waveform and propagation characteristics of the like-Rayleigh waves and studied the influences of the coating transparency,coating thickness,coating viscoelasticity,and substrate viscoelasticity on the propagation characteristics of the like-Rayleigh waves.Moreover,we have verified the results by the theoretical phase velocity and attenuation curves.The results show that the coating viscoelasticity induces the attenuation characteristics of the higher frequencies of the like-Rayleigh waves,but has little effect on the lower frequencies,and the substrate viscoelasticity has the influences on both the higher and lower frequencies of the like-Rayleigh waves,especially the lower frequencies.Furthermore,the mode and dispersive characteristics of the like-Rayleigh waves are closely related to the substrates.This study provides a useful theoretical basis for inverting mechanical parameters and evaluating the adhesive quality of the viscoelastic adhesive coating/substrate structures.
基金National Natural Science Foundation of China,Grant/Award Number:52077012。
文摘The adhesion of carbon particles on the surface of epoxy resin in insulating oil is a significant factor contributing to surface flashover.However,there is currently a lack of a dynamic model that can reasonably explain the adhesion process of impurity particles,and the characteristics of particle adhesion are not yet clear,making it difficult to assess the risks of insulation contamination and surface flashover of valve-side bushing capacitance core.In this study,based on the Johnson-Kendall-Roberts(JKR)theory and the normal distribution characteristics of particle charges,the adhesion probability model of conductive particles in insulating oil on the surface of epoxy resin under DC electric fields was established,and carbon particle adhesion experiments were conducted to verify the accuracy of the model.The impact of electric field intensity,particle size,particle charge,and surface energy of the insulation material on the adhesion characteristics of carbon particles was investigated using the proposed model.The results can be utilised for the assessment of insulation contamination risks of valve-side bushing capacitance core and serves as a vital theoretical foundation for guiding the optimisation of anticontamination structures in internal insulation and the development of advanced pollution-resistant and flashover-resistant insulation materials.
