Three-dimensional simulations of ferroelectric hysteresis and butterfly loops are carried out based on solving the time dependent Ginzburg-Landau equations using a finite volume method. The influence of externally mec...Three-dimensional simulations of ferroelectric hysteresis and butterfly loops are carried out based on solving the time dependent Ginzburg-Landau equations using a finite volume method. The influence of externally mechanical loadings with a tensile strain and a compressive strain on the hysteresis and butterfly loops is studied numerically. Different from the traditional finite element and finite difference methods, the finite volume method is applicable to simulate the ferroelectric phase transitions and properties of ferroelectric materials even for more realistic and physical problems.展开更多
The low cycle fatigue(LCF)behaviors and cyclic deformation mechanisms of 2195 Al-Li alloy were inves-tigated under low temperatures(-20℃and-80℃)and different strain amplitudes(0.6%,0.7%,0.8%,and 1.0%).The LCF stress...The low cycle fatigue(LCF)behaviors and cyclic deformation mechanisms of 2195 Al-Li alloy were inves-tigated under low temperatures(-20℃and-80℃)and different strain amplitudes(0.6%,0.7%,0.8%,and 1.0%).The LCF stress responses under conditions of-20℃&0.6%and-80℃&0.6%exhibited initial cyclic hardening followed by cyclic softening.In contrast,the alloy under other LCF conditions displayed continuous cyclic softening.Notably,the alloy demonstrated reduced LCF life under conditions of-80℃and various strain amplitudes.The fatigue life model based on the total strain energy was developed and proven to be more accurate in predicting fatigue life under diverse LCF conditions.Furthermore,the combined kinematic/isotropic hardening constitutive model exhibited excellent performance in simulat-ing hysteresis loops of the alloy,with corresponding calibration errors all below 14%.Additionally,fatigue fracture surfaces under various LCF conditions consistently exhibited prominent cleavage fracture char-acteristics,and the final fracture zone at-80℃showed increased surface roughness.Finally,the cyclic softening mechanisms were found to be dependent on LCF conditions.The debonding of the interface be-tween the T1 phases and the Al matrix was identified as the primary cyclic softening mechanism under conditions of-20℃&0.6%and-80℃&0.6%.Moreover,the cyclic softening effect under-80℃&1.0%was closely associated with localized shearing of T1 phases.Under-20℃&1.0%,a more pronounced cyclic softening behavior was observed,which was primarily attributed to the continuous shearing of T1 phases.展开更多
基金Supported by the Research Starting Funds for Imported Talents of Ningxia University under Grant No BQD2012011
文摘Three-dimensional simulations of ferroelectric hysteresis and butterfly loops are carried out based on solving the time dependent Ginzburg-Landau equations using a finite volume method. The influence of externally mechanical loadings with a tensile strain and a compressive strain on the hysteresis and butterfly loops is studied numerically. Different from the traditional finite element and finite difference methods, the finite volume method is applicable to simulate the ferroelectric phase transitions and properties of ferroelectric materials even for more realistic and physical problems.
基金supported by the National Natural Science Foundation of China(U23A20626)the Key Research and Devel-opment Program of Shandong Province(2021ZLGX01)the Project of Colleges and Universities Innovation Team of Jinan City(2021GXRC030).
文摘The low cycle fatigue(LCF)behaviors and cyclic deformation mechanisms of 2195 Al-Li alloy were inves-tigated under low temperatures(-20℃and-80℃)and different strain amplitudes(0.6%,0.7%,0.8%,and 1.0%).The LCF stress responses under conditions of-20℃&0.6%and-80℃&0.6%exhibited initial cyclic hardening followed by cyclic softening.In contrast,the alloy under other LCF conditions displayed continuous cyclic softening.Notably,the alloy demonstrated reduced LCF life under conditions of-80℃and various strain amplitudes.The fatigue life model based on the total strain energy was developed and proven to be more accurate in predicting fatigue life under diverse LCF conditions.Furthermore,the combined kinematic/isotropic hardening constitutive model exhibited excellent performance in simulat-ing hysteresis loops of the alloy,with corresponding calibration errors all below 14%.Additionally,fatigue fracture surfaces under various LCF conditions consistently exhibited prominent cleavage fracture char-acteristics,and the final fracture zone at-80℃showed increased surface roughness.Finally,the cyclic softening mechanisms were found to be dependent on LCF conditions.The debonding of the interface be-tween the T1 phases and the Al matrix was identified as the primary cyclic softening mechanism under conditions of-20℃&0.6%and-80℃&0.6%.Moreover,the cyclic softening effect under-80℃&1.0%was closely associated with localized shearing of T1 phases.Under-20℃&1.0%,a more pronounced cyclic softening behavior was observed,which was primarily attributed to the continuous shearing of T1 phases.
