Two-way shape memory effect (TWSME) was induced into the TiNi shape memoryalloys (SMAs) spring by thermomechanical training after annealing treatment, which has promisingapplication in micro-actuating fields. The TWSM...Two-way shape memory effect (TWSME) was induced into the TiNi shape memoryalloys (SMAs) spring by thermomechanical training after annealing treatment, which has promisingapplication in micro-actuating fields. The TWSME spring can contract upon heating and extend uponcooling. The results show that there is an increase of the recovery ratio up to a maximum TWSME of45%. During the training procedure, transformation temperatures and hysteresis were measured bydifferent scanning calorimetry (DSC). The results show that A_s (reverse transformation starttemperature) and A_f (reverse transformation finish temperature) shift to lower temperature aftertraining. The intervals of A_fA_s and M_s-M_f (M_s and M_f are the martensite start and finishtemperatures, respectively) increase and the heat of transformation decreases after training. Theelectrothermal driving characteristics of the TWSME springs were also investigated with alternatingcurrent density of 3.2-14.7 A/mm^2. It is found that the time response and the maximum contractionratio greatly depend on the magnitude of the electrical current density.展开更多
驱动弹簧是有载分接开关(on-load tap changer,OLTC)切换过程中唯一的能量来源,其服役过程中需要被反复切换,有发生疲劳破坏和性能退化的风险。因此,有必要研究其松弛性能对分接开关切换可靠性的影响。该文针对OLTC驱动弹簧开展研究,首...驱动弹簧是有载分接开关(on-load tap changer,OLTC)切换过程中唯一的能量来源,其服役过程中需要被反复切换,有发生疲劳破坏和性能退化的风险。因此,有必要研究其松弛性能对分接开关切换可靠性的影响。该文针对OLTC驱动弹簧开展研究,首先阐明其工作机理与数学模型,提出刚柔耦合仿真方法与油阻尼辨识方法,优化了OLTC动力学模型。其次,开展实际工况下的弹簧疲劳性能测试,推导出弹簧松弛率与振动次数的对数呈线性相关;最后,结合仿真优化与试验数据,分析不同弹簧松弛率对OLTC动力学特性与电气性能的影响。研究结果可为OLTC参数设计与运行工况评估提供一定参考。展开更多
本文以平面运动的三关节机械臂为例,建立它的力学模型和动力学方程。采用D. A. Haessig. Jr等提出的重新定位(Reset Integrator)摩擦模型,用数值方法研究典型激励下机械臂运动的响应,比较不同参数情况的计算结果,发现摩擦力对运动的影...本文以平面运动的三关节机械臂为例,建立它的力学模型和动力学方程。采用D. A. Haessig. Jr等提出的重新定位(Reset Integrator)摩擦模型,用数值方法研究典型激励下机械臂运动的响应,比较不同参数情况的计算结果,发现摩擦力对运动的影响大小不仅取决于摩擦系数的大小,而且与关节传动刚度、驱动速度和重力均有密切关系。展开更多
基金This project is financially supported by the National Natural Science Foundation of China (No. 10175042)
文摘Two-way shape memory effect (TWSME) was induced into the TiNi shape memoryalloys (SMAs) spring by thermomechanical training after annealing treatment, which has promisingapplication in micro-actuating fields. The TWSME spring can contract upon heating and extend uponcooling. The results show that there is an increase of the recovery ratio up to a maximum TWSME of45%. During the training procedure, transformation temperatures and hysteresis were measured bydifferent scanning calorimetry (DSC). The results show that A_s (reverse transformation starttemperature) and A_f (reverse transformation finish temperature) shift to lower temperature aftertraining. The intervals of A_fA_s and M_s-M_f (M_s and M_f are the martensite start and finishtemperatures, respectively) increase and the heat of transformation decreases after training. Theelectrothermal driving characteristics of the TWSME springs were also investigated with alternatingcurrent density of 3.2-14.7 A/mm^2. It is found that the time response and the maximum contractionratio greatly depend on the magnitude of the electrical current density.
文摘驱动弹簧是有载分接开关(on-load tap changer,OLTC)切换过程中唯一的能量来源,其服役过程中需要被反复切换,有发生疲劳破坏和性能退化的风险。因此,有必要研究其松弛性能对分接开关切换可靠性的影响。该文针对OLTC驱动弹簧开展研究,首先阐明其工作机理与数学模型,提出刚柔耦合仿真方法与油阻尼辨识方法,优化了OLTC动力学模型。其次,开展实际工况下的弹簧疲劳性能测试,推导出弹簧松弛率与振动次数的对数呈线性相关;最后,结合仿真优化与试验数据,分析不同弹簧松弛率对OLTC动力学特性与电气性能的影响。研究结果可为OLTC参数设计与运行工况评估提供一定参考。
文摘本文以平面运动的三关节机械臂为例,建立它的力学模型和动力学方程。采用D. A. Haessig. Jr等提出的重新定位(Reset Integrator)摩擦模型,用数值方法研究典型激励下机械臂运动的响应,比较不同参数情况的计算结果,发现摩擦力对运动的影响大小不仅取决于摩擦系数的大小,而且与关节传动刚度、驱动速度和重力均有密切关系。
