为提高层合板损伤检测的准确性与灵敏度,基于聚偏二氟乙烯(polyvinylidene fluoride,PVDF)梳状换能器激发的零群速度(zero group velocity,ZGV)Lamb波,提出了一种层合板损伤的检测方法。采用二维时域有限元方法,研究了PVDF梳状换能器对...为提高层合板损伤检测的准确性与灵敏度,基于聚偏二氟乙烯(polyvinylidene fluoride,PVDF)梳状换能器激发的零群速度(zero group velocity,ZGV)Lamb波,提出了一种层合板损伤的检测方法。采用二维时域有限元方法,研究了PVDF梳状换能器对零群速度Lamb波的激励,通过改变层合板中铝层杨氏模量来表征不同的损伤程度,分析了PVDF梳状换能器电压响应特性与层合板损伤程度之间的关系。结果表明:采用PVDF梳状换能器能够有效激励零群速度Lamb波,并获得层合板内部的状态信息。随着损伤程度的增加,PVDF梳状换能器响应的零群速度共振峰频域幅值随着铝层杨氏模量的减小而显著减少,进而灵敏地评价层合板损伤变化。研究结果说明优化设计的PVDF梳状换能器在零群速度Lamb波的激发与接收性能上都具有优越性,能够有效检测层合板损伤情况。展开更多
固态电池因其优异的性能备受关注,但是与传统的液态电池相比,离子传输能力偏弱,原因是固-固界面离子传输困难。本文制备了以聚偏氟乙烯-六氟丙烯(PVDF-HFP)为基的固态电解质膜,并探究PVDF-HFP和增塑剂乙氧基化三羟甲基丙烷三丙烯酸酯(ET...固态电池因其优异的性能备受关注,但是与传统的液态电池相比,离子传输能力偏弱,原因是固-固界面离子传输困难。本文制备了以聚偏氟乙烯-六氟丙烯(PVDF-HFP)为基的固态电解质膜,并探究PVDF-HFP和增塑剂乙氧基化三羟甲基丙烷三丙烯酸酯(ETPTA)质量比为1.0∶0.3、1.0∶0.4、1.0∶0.5时对电解质膜离子传输的影响,并组装成以磷酸铁锂为正极、锂片为负极的固态电池,研究其电化学性能。研究发现:当PVDF-HFP和ETPT质量比为1.0∶0.4时,锂离子迁移数达0.89,电化学窗口可达4 V,离子电导率达到8×10^(-5)S/cm,表现出良好的稳定性。将质量比为1.0∶0.4的电解质膜装配成固态电池,经过激活之后,首先在0.1C的倍率下进行测试,首圈充电比容量为133 m A·h/g,首圈放电比容量为129 m A·h/g,在20圈循环测试后,放电比容量也能保持在120 mA·h/g以上,容量保持率为92%。展开更多
Graphene prepared by non-covalent modification of sulfonated poly(ether-ether-ketone)(SPG)was combined with polyvinylidene fluoride(PVDF)/Al to improve the PVDF/Al thermal conductivity while reducing the effect of the...Graphene prepared by non-covalent modification of sulfonated poly(ether-ether-ketone)(SPG)was combined with polyvinylidene fluoride(PVDF)/Al to improve the PVDF/Al thermal conductivity while reducing the effect of the thermal resistance at the graphene-polymer interface.The regulation rule of SPG with different contents on the energy release of fluorine-containing system was studied.When the content of SPG is 4%,the peak pressure and rise rate of SPG/PVDF/Al composite powder during ignition reach the maximum of 4845.28 kPa and 8683.58 kPa/s.When the content of SPG is 5%,the PVDF/Al composite powder is completely coated by SPG,and the calorific value of the material reachs the maximum of 29.094 kJ/g.Through the design and micro-control of the composite powder,the calorific value of the material can be effectively improved,but the improvement of the mass release rate still depends on the graphene content and surface modification state.展开更多
文摘为提高层合板损伤检测的准确性与灵敏度,基于聚偏二氟乙烯(polyvinylidene fluoride,PVDF)梳状换能器激发的零群速度(zero group velocity,ZGV)Lamb波,提出了一种层合板损伤的检测方法。采用二维时域有限元方法,研究了PVDF梳状换能器对零群速度Lamb波的激励,通过改变层合板中铝层杨氏模量来表征不同的损伤程度,分析了PVDF梳状换能器电压响应特性与层合板损伤程度之间的关系。结果表明:采用PVDF梳状换能器能够有效激励零群速度Lamb波,并获得层合板内部的状态信息。随着损伤程度的增加,PVDF梳状换能器响应的零群速度共振峰频域幅值随着铝层杨氏模量的减小而显著减少,进而灵敏地评价层合板损伤变化。研究结果说明优化设计的PVDF梳状换能器在零群速度Lamb波的激发与接收性能上都具有优越性,能够有效检测层合板损伤情况。
文摘固态电池因其优异的性能备受关注,但是与传统的液态电池相比,离子传输能力偏弱,原因是固-固界面离子传输困难。本文制备了以聚偏氟乙烯-六氟丙烯(PVDF-HFP)为基的固态电解质膜,并探究PVDF-HFP和增塑剂乙氧基化三羟甲基丙烷三丙烯酸酯(ETPTA)质量比为1.0∶0.3、1.0∶0.4、1.0∶0.5时对电解质膜离子传输的影响,并组装成以磷酸铁锂为正极、锂片为负极的固态电池,研究其电化学性能。研究发现:当PVDF-HFP和ETPT质量比为1.0∶0.4时,锂离子迁移数达0.89,电化学窗口可达4 V,离子电导率达到8×10^(-5)S/cm,表现出良好的稳定性。将质量比为1.0∶0.4的电解质膜装配成固态电池,经过激活之后,首先在0.1C的倍率下进行测试,首圈充电比容量为133 m A·h/g,首圈放电比容量为129 m A·h/g,在20圈循环测试后,放电比容量也能保持在120 mA·h/g以上,容量保持率为92%。
基金Funded by the National Natural Science Foundation of China(No.52104363)。
文摘Graphene prepared by non-covalent modification of sulfonated poly(ether-ether-ketone)(SPG)was combined with polyvinylidene fluoride(PVDF)/Al to improve the PVDF/Al thermal conductivity while reducing the effect of the thermal resistance at the graphene-polymer interface.The regulation rule of SPG with different contents on the energy release of fluorine-containing system was studied.When the content of SPG is 4%,the peak pressure and rise rate of SPG/PVDF/Al composite powder during ignition reach the maximum of 4845.28 kPa and 8683.58 kPa/s.When the content of SPG is 5%,the PVDF/Al composite powder is completely coated by SPG,and the calorific value of the material reachs the maximum of 29.094 kJ/g.Through the design and micro-control of the composite powder,the calorific value of the material can be effectively improved,but the improvement of the mass release rate still depends on the graphene content and surface modification state.