Ferromagnetic high damping(FHA)alloys with a wide temperature range from-150℃to 300℃have unique application value in extreme environments.In the present work,the damping behaviors of Fe-21 Ga-xLa(x=0.12 wt.%,0.24 wt...Ferromagnetic high damping(FHA)alloys with a wide temperature range from-150℃to 300℃have unique application value in extreme environments.In the present work,the damping behaviors of Fe-21 Ga-xLa(x=0.12 wt.%,0.24 wt.%,0.47 wt.%,1.18 wt.%,and 2.33 wt.%La)alloys have been studied in detail,and a new phenomenological model has been proposed.With the increase of La content,the Laves phase(LaGa_(2))in the matrix increases gradually,and the resistance opposing the domain movement increases as well.Combined with the results of synchrotron radiation X-ray diffraction,neutron diffraction,and magnetic domain observation,the resistance mainly comes from three parts:the average stress related to the lattice distortion of the matrix,the average stress related to the increasing area energy of domain walls(DWs),and the ave rage stress related to the increasing demagnetization energy induced by the Laves phase.Different from the traditional method of reducing internal stress through annealing to improve the damping capacity,the proper internal stress barriers are necessary to Barkhausen jumps to dissipate energy.Therefore,proper doping to balance resistance and mobility of DWs is a reliable way to improve damping capacity.Meanwhile,for Fe-Al and Fe-Cr based Alloys,the new model also has a good fitting effect.This study provides a theoretical and experimental reference for improving the functional properties of ferromagnetic alloys.展开更多
The longitudinal mechanical behavior of shape memory alloy （SMA） composite lamina subjected to longitudinally strain or stress controlled cyclic loading is investigated. The SMA is under pseudoelastic condition and ...The longitudinal mechanical behavior of shape memory alloy （SMA） composite lamina subjected to longitudinally strain or stress controlled cyclic loading is investigated. The SMA is under pseudoelastic condition and the fibers are embedded （bonded） to the host material. The influences of temperature, volume fraction of SMA and longitudinal modulus of the host material on the stress-strain relation and energy dissipation of the SMA hybrid composite lamina are discussed. The results indicate that the stress-strain curve of the lamina per cycle shows a hysteresis loop. The hysteresis damping decreases with increasing temperature and with decreasing volume fractions of SMA. In addition, the hysteresis damping is nearly independent of the longitudinal modulus of the host material under strain controlled loading. However, it depends dramatically on the longitudinal modulus of the host material under stress controlled loading, which shows the SMA composite lamina has high pseudo-elastic hysteresis damping when the longitudinal modulus of the host material is low.展开更多
A new kind of passive damping device that is composed of TiNi shape memory alloy （SMA） rings is designed.The basic mechanical behaviors of the device are investigated and its damping capacity is analyzed.There still...A new kind of passive damping device that is composed of TiNi shape memory alloy （SMA） rings is designed.The basic mechanical behaviors of the device are investigated and its damping capacity is analyzed.There still exist hysteresis loops during loading and unloading when the deformation of the ring（s） is restricted in the horizontal direction properly,but the force-displacement curves are tilted and not parallel to the abscissa,which can improve the ability to withstand overloading.If there is no restriction,the force-displacement curves of the rings are near linear though the unloading paths are slightly different from those of loading.The basic mechanical and damping properties of the device may be changed by using different numbers of TiNi alloy rings,and the damping capacity will be increased markedly by increasing the number of rings.展开更多
In this study,the damping responses of uniform soil,equi-proportional fly ash,and local soil as a single unit were investigated.The large-strain cyclic triaxial tests were performed for the specimen compacted at the d...In this study,the damping responses of uniform soil,equi-proportional fly ash,and local soil as a single unit were investigated.The large-strain cyclic triaxial tests were performed for the specimen compacted at the desired density(95%e99%of maximum dry density).The compacted specimens were tested under the loading frequency of 0.3e1 Hz with medium confinement of 70e100 kPa.Also,the unsymmetrical behavior of the hysteresis loop was analyzed using three different damping estimation approaches,i.e.symmetric hysteresis loop(SHL),asymmetric hysteresis loop(ASHL),and the modified American Society for Testing and Materials(ASTM)method.The outcome of the study shows for fly ash,local soil,and layered soil-ash,the ASHL technique has the highest damping value,followed by ASTM and then the SHL approach.The specimens prepared under high density and subjected to high confinement show low damping values.However,the specimens tested at high frequency exhibits high damping behavior.Similarly,the damping value of fly ash determined using the SHL and ASHL methods has a similar profile and reaches a maximum at 1%shear strain value before decreasing.The composite stratified deposit exhibits more dependency on relative compaction,confining pressure,and less on loading frequency.Based on the results,it is highly recommended to use the ASHL approach,especially under large strain conditions irrespective of soil type.The maximum damping ratio of stratified deposits is always in between the damping ratio of local soil and fly ash.The damping ratio of stratified soil and local soil is slightly larger than that of the other soils,although the damping ratio of fly ash is equivalent to that of the sand and clayey soil.These results may be helpful in the accurate determination of the damping properties of the layered soil-ash system that is required in the seismic response analysis.展开更多
The response behaviour of an oscillator with Reid hysteresis damping under stationary Gauss white excitation is studied. By means of numerical simulation conducted on computer, the mean square response, probability de...The response behaviour of an oscillator with Reid hysteresis damping under stationary Gauss white excitation is studied. By means of numerical simulation conducted on computer, the mean square response, probability density function and power spectral density function for the response are given. These response characteristics are compared with those predicted by equivalent linearization treatment.展开更多
基金supported financially by the National Natural Science Foundation of China(No.51971212)the Russian Science Foundation(No.19-72-20080)。
文摘Ferromagnetic high damping(FHA)alloys with a wide temperature range from-150℃to 300℃have unique application value in extreme environments.In the present work,the damping behaviors of Fe-21 Ga-xLa(x=0.12 wt.%,0.24 wt.%,0.47 wt.%,1.18 wt.%,and 2.33 wt.%La)alloys have been studied in detail,and a new phenomenological model has been proposed.With the increase of La content,the Laves phase(LaGa_(2))in the matrix increases gradually,and the resistance opposing the domain movement increases as well.Combined with the results of synchrotron radiation X-ray diffraction,neutron diffraction,and magnetic domain observation,the resistance mainly comes from three parts:the average stress related to the lattice distortion of the matrix,the average stress related to the increasing area energy of domain walls(DWs),and the ave rage stress related to the increasing demagnetization energy induced by the Laves phase.Different from the traditional method of reducing internal stress through annealing to improve the damping capacity,the proper internal stress barriers are necessary to Barkhausen jumps to dissipate energy.Therefore,proper doping to balance resistance and mobility of DWs is a reliable way to improve damping capacity.Meanwhile,for Fe-Al and Fe-Cr based Alloys,the new model also has a good fitting effect.This study provides a theoretical and experimental reference for improving the functional properties of ferromagnetic alloys.
基金Funded by The Doctoral Research Grant of Qingdao University of Science&Technology(No.0022098)
文摘The longitudinal mechanical behavior of shape memory alloy （SMA） composite lamina subjected to longitudinally strain or stress controlled cyclic loading is investigated. The SMA is under pseudoelastic condition and the fibers are embedded （bonded） to the host material. The influences of temperature, volume fraction of SMA and longitudinal modulus of the host material on the stress-strain relation and energy dissipation of the SMA hybrid composite lamina are discussed. The results indicate that the stress-strain curve of the lamina per cycle shows a hysteresis loop. The hysteresis damping decreases with increasing temperature and with decreasing volume fractions of SMA. In addition, the hysteresis damping is nearly independent of the longitudinal modulus of the host material under strain controlled loading. However, it depends dramatically on the longitudinal modulus of the host material under stress controlled loading, which shows the SMA composite lamina has high pseudo-elastic hysteresis damping when the longitudinal modulus of the host material is low.
基金The National Natural Science Foundation of China(No.50038010).
文摘A new kind of passive damping device that is composed of TiNi shape memory alloy （SMA） rings is designed.The basic mechanical behaviors of the device are investigated and its damping capacity is analyzed.There still exist hysteresis loops during loading and unloading when the deformation of the ring（s） is restricted in the horizontal direction properly,but the force-displacement curves are tilted and not parallel to the abscissa,which can improve the ability to withstand overloading.If there is no restriction,the force-displacement curves of the rings are near linear though the unloading paths are slightly different from those of loading.The basic mechanical and damping properties of the device may be changed by using different numbers of TiNi alloy rings,and the damping capacity will be increased markedly by increasing the number of rings.
文摘In this study,the damping responses of uniform soil,equi-proportional fly ash,and local soil as a single unit were investigated.The large-strain cyclic triaxial tests were performed for the specimen compacted at the desired density(95%e99%of maximum dry density).The compacted specimens were tested under the loading frequency of 0.3e1 Hz with medium confinement of 70e100 kPa.Also,the unsymmetrical behavior of the hysteresis loop was analyzed using three different damping estimation approaches,i.e.symmetric hysteresis loop(SHL),asymmetric hysteresis loop(ASHL),and the modified American Society for Testing and Materials(ASTM)method.The outcome of the study shows for fly ash,local soil,and layered soil-ash,the ASHL technique has the highest damping value,followed by ASTM and then the SHL approach.The specimens prepared under high density and subjected to high confinement show low damping values.However,the specimens tested at high frequency exhibits high damping behavior.Similarly,the damping value of fly ash determined using the SHL and ASHL methods has a similar profile and reaches a maximum at 1%shear strain value before decreasing.The composite stratified deposit exhibits more dependency on relative compaction,confining pressure,and less on loading frequency.Based on the results,it is highly recommended to use the ASHL approach,especially under large strain conditions irrespective of soil type.The maximum damping ratio of stratified deposits is always in between the damping ratio of local soil and fly ash.The damping ratio of stratified soil and local soil is slightly larger than that of the other soils,although the damping ratio of fly ash is equivalent to that of the sand and clayey soil.These results may be helpful in the accurate determination of the damping properties of the layered soil-ash system that is required in the seismic response analysis.
文摘The response behaviour of an oscillator with Reid hysteresis damping under stationary Gauss white excitation is studied. By means of numerical simulation conducted on computer, the mean square response, probability density function and power spectral density function for the response are given. These response characteristics are compared with those predicted by equivalent linearization treatment.
