As a preliminary step in the nonlinear design of shape memory alloy（SMA） composite structures,the force-displacement characteristics of the SMA layer are studied.The bilinear hysteretic model is adopted to describe ...As a preliminary step in the nonlinear design of shape memory alloy（SMA） composite structures,the force-displacement characteristics of the SMA layer are studied.The bilinear hysteretic model is adopted to describe the constitutive relationship of SMA material.Under the assumption that there is no point of SMA layer finishing martensitic phase transformation during the loading and unloading process,the generalized restoring force generated by SMA layer is deduced for the case that the simply supported beam vibrates in its first mode.The generalized force is expressed as piecewise-nonlinear hysteretic function of the beam transverse displacement.Furthermore the energy dissipated by SMA layer during one period is obtained by integration,then its dependencies are discussed on the vibration amplitude and the SMA＇s strain（Ms-Strain） value at the beginning of martensitic phase transformation.It is shown that SMA＇s energy dissipating capacity is proportional to the stiffness difference of bilinear model and nonlinearly dependent on Ms-Strain.The increasing rate of the dissipating capacity gradually reduces with the amplitude increasing.The condition corresponding to the maximum dissipating capacity is deduced for given value of the vibration amplitude.The obtained results are helpful for designing beams laminated with shape memory alloys.展开更多
Permanent magnet brushless DC motors are used for various low-power applications,namely domestic fans,washing machines,mixer grinders and cooling fan applications.This paper focuses on selecting the best laminating ma...Permanent magnet brushless DC motors are used for various low-power applications,namely domestic fans,washing machines,mixer grinders and cooling fan applications.This paper focuses on selecting the best laminating material for the interior permanent magnet brushless DC(IPM BLDC)motor used in the cooling fan of automobiles.Various laminating materials,namely M19-29GA,M800-65A and M43,are tested using finite element analysis.The machine's vital performance metrics,namely the stator current,torque ripple,and hysteresis loss were analyzed in selecting the laminating material.The designed motor is also modelled as a mathematical model from the computed lumped parameters.The performance of the machines was validated through electromagnetic and thermal analysis.展开更多
基金supported by the National Natural Science Foundation of China (10872142 and 10632040)New Century Excellent Talents in University of China (NCET-05-0247)the Key Program of the Natural Science Foundation of Tianjin (09JCZDJ26800)
文摘As a preliminary step in the nonlinear design of shape memory alloy（SMA） composite structures,the force-displacement characteristics of the SMA layer are studied.The bilinear hysteretic model is adopted to describe the constitutive relationship of SMA material.Under the assumption that there is no point of SMA layer finishing martensitic phase transformation during the loading and unloading process,the generalized restoring force generated by SMA layer is deduced for the case that the simply supported beam vibrates in its first mode.The generalized force is expressed as piecewise-nonlinear hysteretic function of the beam transverse displacement.Furthermore the energy dissipated by SMA layer during one period is obtained by integration,then its dependencies are discussed on the vibration amplitude and the SMA＇s strain（Ms-Strain） value at the beginning of martensitic phase transformation.It is shown that SMA＇s energy dissipating capacity is proportional to the stiffness difference of bilinear model and nonlinearly dependent on Ms-Strain.The increasing rate of the dissipating capacity gradually reduces with the amplitude increasing.The condition corresponding to the maximum dissipating capacity is deduced for given value of the vibration amplitude.The obtained results are helpful for designing beams laminated with shape memory alloys.
文摘Permanent magnet brushless DC motors are used for various low-power applications,namely domestic fans,washing machines,mixer grinders and cooling fan applications.This paper focuses on selecting the best laminating material for the interior permanent magnet brushless DC(IPM BLDC)motor used in the cooling fan of automobiles.Various laminating materials,namely M19-29GA,M800-65A and M43,are tested using finite element analysis.The machine's vital performance metrics,namely the stator current,torque ripple,and hysteresis loss were analyzed in selecting the laminating material.The designed motor is also modelled as a mathematical model from the computed lumped parameters.The performance of the machines was validated through electromagnetic and thermal analysis.
