Sandwich structures are widespread in engineering applications because of their advantageous mechanical properties.Recently,their acoustic performance has also been improved to enable attenuation of low-frequency vibr...Sandwich structures are widespread in engineering applications because of their advantageous mechanical properties.Recently,their acoustic performance has also been improved to enable attenuation of low-frequency vibrations induced by noisy environments.Here,we propose a new design of sandwich plates(SPs)featuring a metamaterial core with an actively tunable low-frequency bandgap.The core contains magnetorheological elastomer(MRE)resonators which are arranged periodically and enable controlling wave attenuation by an external magnetic field.We analytically estimate the sound transmission loss(STL)of the plate using the space harmonic expansion method.The low frequency sound insulation performance is also analyzed by the equivalent dynamic density method,and the accuracy of the obtained results is verified by finite-element simulations.Our results demonstrate that the STL of the proposed plate is enhanced compared with a typical SP analog,and the induced bandgap can be effectively tuned to desired frequencies.This study further advances the field of actively controlled acoustic metamaterials,and paves the way to their practical applications.展开更多
Magnetorheological(MR)materials are a class of smart material,whose the mechanical/rheological state can be controlled under a magnetic field.Magnetorheological materials are typically fluids,gels,or elastomers.In thi...Magnetorheological(MR)materials are a class of smart material,whose the mechanical/rheological state can be controlled under a magnetic field.Magnetorheological materials are typically fluids,gels,or elastomers.In this study,anisotropic and isotropic magneto-rheological elastomer(MRE)samples were fabricated using a silicone rubber matrix with carbonyl iron particles as filler particles.The magnetic field-dependent inductance properties of these samples were studied using inductors specially designed for the analysis.The effect of the filler particle content,fabrication conditions,and inductance properties were characterized using a self-built system in both constant and transient magnetic fields.These factors show a significant effect on the inductance properties of the MRE inductor under an applied magnetic field.The anisotropic MRE inductor was more sensitive than the inductor based on an isotropic MRE.Owing to the presence of a constant magnetic field,the inductance value of the MRE inductor decreased with an increase in the external magnetic field.An attempt in elucidation of the mechanism is reported here.This study may enable the MRE to be widely used in practical applications such as monitoring magnetic field or detecting the filler particle content inside MR materials.展开更多
Magnetorheological elastomer (MRE) is a type of smart material of which mechanical and electrical properties can be reversibly controlled by the magnetic field. In this study, the influence of the magnetic field on th...Magnetorheological elastomer (MRE) is a type of smart material of which mechanical and electrical properties can be reversibly controlled by the magnetic field. In this study, the influence of the magnetic field on the surface roughness of MRE was studied by the microscopic modeling method, and the influence of controllable characteristics of the MRE surface on its friction properties was analyzed by the macroscopic experimental method. First, on the basis of existing studies, an improved mesoscopic model based on magneto-mechanical coupling analysis was proposed. The initial surface morphology of MRE was characterized by the W–M fractal function, and the change process of the surface microstructures of MRE, induced by the magnetic interaction between particles, was studied. Then, after analyzing the simulation results, it is found that with the increase in the magnetic field and decrease in the modulus of rubber matrix, the surface of MRE changes more significantly, and the best particle volume fraction is within 7.5%–9%. Furthermore, through experimental observation, it is found that the height of the convex peak on the surface of MRE decreases significantly with the action of the magnetic field, resulting in a reduction in the surface roughness. Consistent with the simulation results, a particle volume fraction of 10% corresponds to a maximum change of 14%. Finally, the macroscopic friction experiment results show that the friction coefficients of MREs with different particle volume fractions all decrease with the decrease in surface roughness under the magnetic field. When the particle volume fraction is 10%, the friction coefficient can decrease by 24.7% under a magnetic field of 400 mT, which is consistent with the trend of surface roughness changes. This shows that the change in surface morphology with the effect of the magnetic field is an important factor in the control of MRE friction properties by magnetic field.展开更多
In this paper,a novel type of isolator,named segmented intelligent isolation bearing(SIIB),is designed and manufactured,which can meet the requirements of seismic fortification under three seismic intensities,i.e.freq...In this paper,a novel type of isolator,named segmented intelligent isolation bearing(SIIB),is designed and manufactured,which can meet the requirements of seismic fortification under three seismic intensities,i.e.frequent intensity,basic intensity,and rare intensity.A theoretical formula for the output of the SIIB is established to provide a basis for the determination of the size of the SIIB.MRE and STMP used in SIIB were prepared,of which the changes of shear storage modulus and damping factor with the magnetic field under different strain are analyzed.The mechanical properties of the SIIB under small displacement,medium displacement,and large displacement are tested,respectively,and the hysteretic characteristics of force–displacement are analyzed.The dynamic mechanical model combining the rheological model,phenomenological model,and bilinear restoring force model is established to represent the behavior of the SIIB.The results showed that the theoretical results agree well with the experimental results,and the model can significantly reflect the dynamic characteristics of SIIB.展开更多
In this investigation,a new silicone rubber-based MRE material was prepared to be used as a forming medium in manufacturing thin-walled complexshaped Ni-based tubes through the bulging process.Thus,it is significant ...In this investigation,a new silicone rubber-based MRE material was prepared to be used as a forming medium in manufacturing thin-walled complexshaped Ni-based tubes through the bulging process.Thus,it is significant to investigate the effect of magnetic field intensity,magnetic field loading time,and angle on the mechanical properties of the prepared MRE material during the curing process.The obtained results showed that increasing the magnetic field intensity during the curing process can improve the orientation of the chain structure in the elastomer matrix effectively.However,its mechanical properties are the best under the corresponding magnetic field intensity of 321 mT.Besides,by extending the magnetic field loading time in the curing process,the orientation of the chain structure was optimized,at the same time,the mechanical properties were also improved,and the best loading time is about 20–25 min.By changing the loading angle of the magnetic field during the curing process,the mechanical properties of the MRE were improved.When the loading angle of the magnetic field is 90°,the elastomer showed the best compression mechanical properties and excellent compression reversibility.Besides,for the anisotropic MRE material,the performance with magnetic compression is always better than that without magnetic compression.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.12472007 and 12072084)the Fundamental Research Funds for the Central Universities of China。
文摘Sandwich structures are widespread in engineering applications because of their advantageous mechanical properties.Recently,their acoustic performance has also been improved to enable attenuation of low-frequency vibrations induced by noisy environments.Here,we propose a new design of sandwich plates(SPs)featuring a metamaterial core with an actively tunable low-frequency bandgap.The core contains magnetorheological elastomer(MRE)resonators which are arranged periodically and enable controlling wave attenuation by an external magnetic field.We analytically estimate the sound transmission loss(STL)of the plate using the space harmonic expansion method.The low frequency sound insulation performance is also analyzed by the equivalent dynamic density method,and the accuracy of the obtained results is verified by finite-element simulations.Our results demonstrate that the STL of the proposed plate is enhanced compared with a typical SP analog,and the induced bandgap can be effectively tuned to desired frequencies.This study further advances the field of actively controlled acoustic metamaterials,and paves the way to their practical applications.
基金Project(cstc2019jcyj-msxm X0005)supported by General Program of Chongqing Natural Science Foundation,ChinaProject(51905062)supported by the National Natural Science Foundation of China。
文摘Magnetorheological(MR)materials are a class of smart material,whose the mechanical/rheological state can be controlled under a magnetic field.Magnetorheological materials are typically fluids,gels,or elastomers.In this study,anisotropic and isotropic magneto-rheological elastomer(MRE)samples were fabricated using a silicone rubber matrix with carbonyl iron particles as filler particles.The magnetic field-dependent inductance properties of these samples were studied using inductors specially designed for the analysis.The effect of the filler particle content,fabrication conditions,and inductance properties were characterized using a self-built system in both constant and transient magnetic fields.These factors show a significant effect on the inductance properties of the MRE inductor under an applied magnetic field.The anisotropic MRE inductor was more sensitive than the inductor based on an isotropic MRE.Owing to the presence of a constant magnetic field,the inductance value of the MRE inductor decreased with an increase in the external magnetic field.An attempt in elucidation of the mechanism is reported here.This study may enable the MRE to be widely used in practical applications such as monitoring magnetic field or detecting the filler particle content inside MR materials.
基金This work was supported by the National Natural Science Foundation of China (No. 11572320)Science and Technology Research Project of Chongqing Municipal Education Commission (No. KJQN201800644)+1 种基金Special Key Project of Technological Innovation and Application Development in Chongqing (cstc2019jscx-fxyd0005)The authors thank professor Xiaojie WANG from Institute of Advanced Manufacturing Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences and associate professor Shiwei CHEN from Chongqing Institute of Science and Technology for the support and fruitful discussions.
文摘Magnetorheological elastomer (MRE) is a type of smart material of which mechanical and electrical properties can be reversibly controlled by the magnetic field. In this study, the influence of the magnetic field on the surface roughness of MRE was studied by the microscopic modeling method, and the influence of controllable characteristics of the MRE surface on its friction properties was analyzed by the macroscopic experimental method. First, on the basis of existing studies, an improved mesoscopic model based on magneto-mechanical coupling analysis was proposed. The initial surface morphology of MRE was characterized by the W–M fractal function, and the change process of the surface microstructures of MRE, induced by the magnetic interaction between particles, was studied. Then, after analyzing the simulation results, it is found that with the increase in the magnetic field and decrease in the modulus of rubber matrix, the surface of MRE changes more significantly, and the best particle volume fraction is within 7.5%–9%. Furthermore, through experimental observation, it is found that the height of the convex peak on the surface of MRE decreases significantly with the action of the magnetic field, resulting in a reduction in the surface roughness. Consistent with the simulation results, a particle volume fraction of 10% corresponds to a maximum change of 14%. Finally, the macroscopic friction experiment results show that the friction coefficients of MREs with different particle volume fractions all decrease with the decrease in surface roughness under the magnetic field. When the particle volume fraction is 10%, the friction coefficient can decrease by 24.7% under a magnetic field of 400 mT, which is consistent with the trend of surface roughness changes. This shows that the change in surface morphology with the effect of the magnetic field is an important factor in the control of MRE friction properties by magnetic field.
基金This work was the supported by National Natural Science Foundation of China[Grant No.51508237]the Primary Research and Development Plan of Jiangsu Province[Grant no.BE2017167]All data included in this study are available upon request by contact with the corresponding author.
文摘In this paper,a novel type of isolator,named segmented intelligent isolation bearing(SIIB),is designed and manufactured,which can meet the requirements of seismic fortification under three seismic intensities,i.e.frequent intensity,basic intensity,and rare intensity.A theoretical formula for the output of the SIIB is established to provide a basis for the determination of the size of the SIIB.MRE and STMP used in SIIB were prepared,of which the changes of shear storage modulus and damping factor with the magnetic field under different strain are analyzed.The mechanical properties of the SIIB under small displacement,medium displacement,and large displacement are tested,respectively,and the hysteretic characteristics of force–displacement are analyzed.The dynamic mechanical model combining the rheological model,phenomenological model,and bilinear restoring force model is established to represent the behavior of the SIIB.The results showed that the theoretical results agree well with the experimental results,and the model can significantly reflect the dynamic characteristics of SIIB.
基金financially supported by the National Natural Science Foundation of China (No.11462004,51475165)the Natural Science Foundation of Jiangxi Province of China (No.20151BAB206035)+1 种基金Jiangxi Provincial Foundation for Leaders of Academic and Disciplines in Science(No.20162BCB22019)the Educational Commission Project of Jiangxi Province of China (No.GJJ150525)
基金The funding for the investigation in this paper mainly comes from the following funds.Funded by the National Natural Science Foundation Key Project of China(Grant No.U1937206)the authors are Li,Xu,Guo,the specific grant numbers was RMB 100,000.Funded by the Jiangsu Province Key Research and Development Project(No.BE2019007-2)+2 种基金the authors are Abd,Cheng,the specific grant numbers was RMB 200,000.Funded by the Opening Project of Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology(No.ASMA201903)the authors are Wu,Yang,Hu,the specific grant numbers was RMB 50,000.Funded by the Basic Scientific Research Operations(Approval No.NT2020015)the authors are Shen,Tao,Guo,the specific grant numbers was RMB 100,000.
文摘In this investigation,a new silicone rubber-based MRE material was prepared to be used as a forming medium in manufacturing thin-walled complexshaped Ni-based tubes through the bulging process.Thus,it is significant to investigate the effect of magnetic field intensity,magnetic field loading time,and angle on the mechanical properties of the prepared MRE material during the curing process.The obtained results showed that increasing the magnetic field intensity during the curing process can improve the orientation of the chain structure in the elastomer matrix effectively.However,its mechanical properties are the best under the corresponding magnetic field intensity of 321 mT.Besides,by extending the magnetic field loading time in the curing process,the orientation of the chain structure was optimized,at the same time,the mechanical properties were also improved,and the best loading time is about 20–25 min.By changing the loading angle of the magnetic field during the curing process,the mechanical properties of the MRE were improved.When the loading angle of the magnetic field is 90°,the elastomer showed the best compression mechanical properties and excellent compression reversibility.Besides,for the anisotropic MRE material,the performance with magnetic compression is always better than that without magnetic compression.
