The work aims to provide a further investigation of the dynamic characteristics of an integral bladed disk（also called ‘blisk＇） with a Parallel Piezoelectric Network（PPN）. The PPN is constructed by parallelly in...The work aims to provide a further investigation of the dynamic characteristics of an integral bladed disk（also called ‘blisk＇） with a Parallel Piezoelectric Network（PPN）. The PPN is constructed by parallelly interconnecting the piezoelectric patches distributed in the blisk. Two kinds of PPN are considered, namely mono-periodic PPN and bi-periodic PPN. The former has a piezoelectric patch in each sector, and the later has one patch every few sectors. The vibration suppression performance of both kinds of PPN has been studied through modal analysis, forced response analysis, and statistical analysis. The research results turn out that the PPN will only affect mechanical frequencies near the electrical frequency clusters slightly, and the bi-periodic PPN will make the nodal diameter spectrum of the modes more complex, but the amplitude corresponding to the new nodal diameter component is much smaller than that of the nodal diameter component corresponding to the mono-periodic system. The mechanical coupling between the blades and the disk plays an important role in the damping effect of the PPN, and it should be paid attention to in applications. The mono-periodic PPN can effectively suppress the amplitude magnification of the forced response induced by the mistuning of the blisk; meanwhile, it can mitigate the vibration localization of the mistuned electromechanical system. If piezoelectric patches are set only in part of the sectors, the bi-periodic PPN still has a vibration suppression ability, but the effect is related to the number and spatial distribution of the piezoelectric patches.展开更多
Electromagnetic interference pollution has raised urgent demand for the development of electromagnetic interference shielding materials.Transition metal carbides(MXenes)with excellent conductivity have shown great pot...Electromagnetic interference pollution has raised urgent demand for the development of electromagnetic interference shielding materials.Transition metal carbides(MXenes)with excellent conductivity have shown great potential in electromagnetic interference(EMI)shielding materials,while the poor mechanical strength,flexibility,and structural stability greatly limit their further applications.Here,cellulose nanofibers and sodium alginate are incorporated with MXene nanosheets as flexible matrices to construct strong and flexible mussellike layered MXene/Cellulose nanofiber/Sodium Alginate composite films,and nickel ions are further introduced to induce metal coordination crosslinking of alginate units.Benefited from the dual-crosslinked network structure of hydrogen bonding and metal coordination,the tensile strength,Young’s modulus,and toughness of the MXene/cellulose nanofiber/nickel alginate composite film are significantly increased.After subsequent reduction by ascorbic acid,excess nickel ions are reduced to nickel nanoparticles and uniformly dispersed within the highly conductive composite film,which further improved its hysteresis loss effect toward the incident electromagnetic waves.Consequently,the MXene/cellulose nanofiber/nickel alginate-Ni composite film presents a considerably enhanced electromagnetic interference shielding effectiveness(47.17 dB)at a very low thickness of 29μm.This study proposes a feasible dual-crosslinking and subsequent reduction strategy to synergistically enhance the mechanical properties and electromagnetic interference shielding performance of MXene-based composite materials.展开更多
Herein,a one-pot method is proposed to manufacture recyclable polyvinyl alcohol/cellulose nanofibers composites with excellent mechanical and barrier performance through wet co-milling of the 2,2,6,6-tetramethylpiperi...Herein,a one-pot method is proposed to manufacture recyclable polyvinyl alcohol/cellulose nanofibers composites with excellent mechanical and barrier performance through wet co-milling of the 2,2,6,6-tetramethylpiperidine-1-oxyl oxidized bamboo pulp in the polyvinyl alcohol aqueous solution.This strategy achieves ultrafine nano-fibrillation of cellulose pulp into nanofibers and their simultaneous homogenous distribution in the polyvinyl alcohol matrix,as evidenced by the homogenized structural morphology and enhanced interfacial interactions.With increased grinding degree,the cellulose fibers are gradually exfoliated and uniformly distributed in the polyvinyl alcohol matrix.The structure evolution of polyvinyl alcohol/cellulose composites during exfoliation and the structure-properties relationship are systematically analyzed.Consequently,the resultant polyvinyl alcohol/cellulose nanofibers composite films exhibit a‘reinforced concrete’structure with improved grain boundary strengthening effect,stress transfer capability and barrier properties.The elastic modulus,tensile strength and toughness of the polyvinyl alcohol/cellulose nanofibers composite films are significantly enhanced by 195.1%,33.8%and 56.2%compared to those of pure polyvinyl alcohol film,respectively.The greatly reduced oxygen permeability coefficient demonstrates their great potential in food packaging.This research proposes a practical one-pot method for the fabrication and structure regulation of polyvinyl alcohol/cellulose nanofibers composites and provides valuable insights into their structure-property relationships.展开更多
基金support of the National Natural Science Foundation of China (No. 51675022, 11702011)China Postdoctoral Science Foundation (No. 2017M610741)
文摘The work aims to provide a further investigation of the dynamic characteristics of an integral bladed disk（also called ‘blisk＇） with a Parallel Piezoelectric Network（PPN）. The PPN is constructed by parallelly interconnecting the piezoelectric patches distributed in the blisk. Two kinds of PPN are considered, namely mono-periodic PPN and bi-periodic PPN. The former has a piezoelectric patch in each sector, and the later has one patch every few sectors. The vibration suppression performance of both kinds of PPN has been studied through modal analysis, forced response analysis, and statistical analysis. The research results turn out that the PPN will only affect mechanical frequencies near the electrical frequency clusters slightly, and the bi-periodic PPN will make the nodal diameter spectrum of the modes more complex, but the amplitude corresponding to the new nodal diameter component is much smaller than that of the nodal diameter component corresponding to the mono-periodic system. The mechanical coupling between the blades and the disk plays an important role in the damping effect of the PPN, and it should be paid attention to in applications. The mono-periodic PPN can effectively suppress the amplitude magnification of the forced response induced by the mistuning of the blisk; meanwhile, it can mitigate the vibration localization of the mistuned electromechanical system. If piezoelectric patches are set only in part of the sectors, the bi-periodic PPN still has a vibration suppression ability, but the effect is related to the number and spatial distribution of the piezoelectric patches.
基金supported by the Sichuan Science and Technology Program(Grant No.2022YFG0291)State Key Laboratory of Polymer Materials Engineering(Grant No.sklpme2022-3-20)the Program for Featured Directions of Engineering Multi-disciplines of Sichuan University(Grant No.2020SCUNG203).
文摘Electromagnetic interference pollution has raised urgent demand for the development of electromagnetic interference shielding materials.Transition metal carbides(MXenes)with excellent conductivity have shown great potential in electromagnetic interference(EMI)shielding materials,while the poor mechanical strength,flexibility,and structural stability greatly limit their further applications.Here,cellulose nanofibers and sodium alginate are incorporated with MXene nanosheets as flexible matrices to construct strong and flexible mussellike layered MXene/Cellulose nanofiber/Sodium Alginate composite films,and nickel ions are further introduced to induce metal coordination crosslinking of alginate units.Benefited from the dual-crosslinked network structure of hydrogen bonding and metal coordination,the tensile strength,Young’s modulus,and toughness of the MXene/cellulose nanofiber/nickel alginate composite film are significantly increased.After subsequent reduction by ascorbic acid,excess nickel ions are reduced to nickel nanoparticles and uniformly dispersed within the highly conductive composite film,which further improved its hysteresis loss effect toward the incident electromagnetic waves.Consequently,the MXene/cellulose nanofiber/nickel alginate-Ni composite film presents a considerably enhanced electromagnetic interference shielding effectiveness(47.17 dB)at a very low thickness of 29μm.This study proposes a feasible dual-crosslinking and subsequent reduction strategy to synergistically enhance the mechanical properties and electromagnetic interference shielding performance of MXene-based composite materials.
基金supported by the Tianfu Yongxing Laboratory Organized Research Project Funding(Grant No.2023KJGG12)the Joint Project for Talent Innovation Sharing Alliance of Quanzhou(Grant No.2022C001L)+1 种基金the Opening Project of Guangxi Key Laboratory of Calcium Carbonate Resources Comprehensive Utilization(Grant No.HZXYKFKT202306)the Guangxi Science and Technology Base and Special Talents Program(Grant No.AD23023008).
文摘Herein,a one-pot method is proposed to manufacture recyclable polyvinyl alcohol/cellulose nanofibers composites with excellent mechanical and barrier performance through wet co-milling of the 2,2,6,6-tetramethylpiperidine-1-oxyl oxidized bamboo pulp in the polyvinyl alcohol aqueous solution.This strategy achieves ultrafine nano-fibrillation of cellulose pulp into nanofibers and their simultaneous homogenous distribution in the polyvinyl alcohol matrix,as evidenced by the homogenized structural morphology and enhanced interfacial interactions.With increased grinding degree,the cellulose fibers are gradually exfoliated and uniformly distributed in the polyvinyl alcohol matrix.The structure evolution of polyvinyl alcohol/cellulose composites during exfoliation and the structure-properties relationship are systematically analyzed.Consequently,the resultant polyvinyl alcohol/cellulose nanofibers composite films exhibit a‘reinforced concrete’structure with improved grain boundary strengthening effect,stress transfer capability and barrier properties.The elastic modulus,tensile strength and toughness of the polyvinyl alcohol/cellulose nanofibers composite films are significantly enhanced by 195.1%,33.8%and 56.2%compared to those of pure polyvinyl alcohol film,respectively.The greatly reduced oxygen permeability coefficient demonstrates their great potential in food packaging.This research proposes a practical one-pot method for the fabrication and structure regulation of polyvinyl alcohol/cellulose nanofibers composites and provides valuable insights into their structure-property relationships.
