机器人加工是航天复杂舱段内腔加工的有效手段。针对部分狭窄深腔舱段的加工需求,需在机器人末端附加延长杆以提升操作可达性。然而,延长杆在拓展加工覆盖范围的同时,会增大系统动柔度,极易引发加工颤振,进而影响加工质量与效率。为此,...机器人加工是航天复杂舱段内腔加工的有效手段。针对部分狭窄深腔舱段的加工需求,需在机器人末端附加延长杆以提升操作可达性。然而,延长杆在拓展加工覆盖范围的同时,会增大系统动柔度,极易引发加工颤振,进而影响加工质量与效率。为此,本文提出一种变频可调式调谐质量阻尼器(Tuned mass damper,TMD)的结构设计与参数优化方法,建立了集成调谐质量阻尼器与机器人加工系统的动力学模型。该方法基于偏心曲柄滑块机构实现频率可调,根据电涡流阻尼原理完成阻尼参数调控。进一步开展机器人加工系统动柔度控制试验,结果表明,本文所提方法可使末端动柔度峰值降低67.8%,显著提升加工稳定性边界。展开更多
2D materials including graphene and TMDs have proven interesting physical properties and promising optoelectronic applications.We reviewed the growth,characterization and optoelectronics based on 2D TMDs and their het...2D materials including graphene and TMDs have proven interesting physical properties and promising optoelectronic applications.We reviewed the growth,characterization and optoelectronics based on 2D TMDs and their heterostructures,and demonstrated their unique and high quality of performances.For example,we observed the large mobility,fast response and high photo-responsivity in Mo S;,WS;and WSe;phototransistors,as well as the novel performances in vd W heterostructures such as the strong interlayer coupling,am-bipolar and rectifying behaviour,and the obvious photovoltaic effect.It is being possible that 2D family materials could play an increasingly important role in the future nano- and opto-electronics,more even than traditional semiconductors such as silicon.展开更多
为研究人行桥人致振动控制问题,推导了基于随机行走模型的人-桥-TMD(tuned mass damper)耦合运动方程;计算分析了不同模态质量下的峰值加速度、一阶瞬时阻尼比、一阶瞬时频率及其耦合效应;以荆州市某人行天桥为例,进行了减振效果实测,...为研究人行桥人致振动控制问题,推导了基于随机行走模型的人-桥-TMD(tuned mass damper)耦合运动方程;计算分析了不同模态质量下的峰值加速度、一阶瞬时阻尼比、一阶瞬时频率及其耦合效应;以荆州市某人行天桥为例,进行了减振效果实测,并对舒适度不满足要求的模态进行减振优化设计。结果表明:在同一随机人群密度下,结构的一阶瞬时阻尼比随着模态质量的增大而增大,结构一阶瞬时频率随着模态质量的增大而降低;在TMD振动控制下,T_(c)=0.2,0.4,0.8,1.2人/m^(2)四种工况的减振率分别为76%、73%、69%、56%,平均减振率达到68.5%,减振率随着人群密度的增大呈现出先增大后减小的趋势。该类结果对人行桥振动控制具有参考借鉴意义。展开更多
文摘机器人加工是航天复杂舱段内腔加工的有效手段。针对部分狭窄深腔舱段的加工需求,需在机器人末端附加延长杆以提升操作可达性。然而,延长杆在拓展加工覆盖范围的同时,会增大系统动柔度,极易引发加工颤振,进而影响加工质量与效率。为此,本文提出一种变频可调式调谐质量阻尼器(Tuned mass damper,TMD)的结构设计与参数优化方法,建立了集成调谐质量阻尼器与机器人加工系统的动力学模型。该方法基于偏心曲柄滑块机构实现频率可调,根据电涡流阻尼原理完成阻尼参数调控。进一步开展机器人加工系统动柔度控制试验,结果表明,本文所提方法可使末端动柔度峰值降低67.8%,显著提升加工稳定性边界。
文摘2D materials including graphene and TMDs have proven interesting physical properties and promising optoelectronic applications.We reviewed the growth,characterization and optoelectronics based on 2D TMDs and their heterostructures,and demonstrated their unique and high quality of performances.For example,we observed the large mobility,fast response and high photo-responsivity in Mo S;,WS;and WSe;phototransistors,as well as the novel performances in vd W heterostructures such as the strong interlayer coupling,am-bipolar and rectifying behaviour,and the obvious photovoltaic effect.It is being possible that 2D family materials could play an increasingly important role in the future nano- and opto-electronics,more even than traditional semiconductors such as silicon.
文摘为研究人行桥人致振动控制问题,推导了基于随机行走模型的人-桥-TMD(tuned mass damper)耦合运动方程;计算分析了不同模态质量下的峰值加速度、一阶瞬时阻尼比、一阶瞬时频率及其耦合效应;以荆州市某人行天桥为例,进行了减振效果实测,并对舒适度不满足要求的模态进行减振优化设计。结果表明:在同一随机人群密度下,结构的一阶瞬时阻尼比随着模态质量的增大而增大,结构一阶瞬时频率随着模态质量的增大而降低;在TMD振动控制下,T_(c)=0.2,0.4,0.8,1.2人/m^(2)四种工况的减振率分别为76%、73%、69%、56%,平均减振率达到68.5%,减振率随着人群密度的增大呈现出先增大后减小的趋势。该类结果对人行桥振动控制具有参考借鉴意义。
