报告题目：Dynamic Analysis and Design of the Nutation Damper for the Infrared Seekers (红外线寻标投章动阻尼器的动力学分析与设计)
报 告 人：张家欧 教授
时 间：9月17日 上午9:30-10:30
地点：浙江大学玉泉校区教四311教室
交流内容及邀请专家人介绍：
报告简介：
红外线寻标器是以红外线追踪目标物(飞机、飞弹)的热源而在寻标器内的Focal plane array芯片形成目标物影像。由影像可确知目标物与寻标头的相对角度误差，由回授控制电路启动驱动线圈产生脉冲磁场来使自旋转子转向对准目标物转动。转子是以两个旋转自由度的gimbals与寻标头连接，当脉冲磁场作用在磁性转子上时，会使转子产生coining motion (wobble motion)，无法精确锁住目标；为消除此晃动，而加装圆环形水银阻尼器，将自旋转子的横向角动量转换成自旋轴向角动量转。因章动与进动造成部分充填的水银在圆环管内形成有自由面的偏心环状，此偏心水银环有相对于圆环管的相对滑动。为推导水银与转子刚体的运动方程序，我们将水银仿真成可变形的偏心条块，即此条块的偏心量是随时间在变的变數，偏心量会随晃动的角度变小而逐渐消失。利用拉格兰治方成程序推导五个自由度(转子三自由度，水银两自由度)的运动方程序及水银作用在转子的广义力与力矩，数值解可得章动角衰退的时间常数。此时间常数愈小表示转子晃动能愈快被消除。可分析得最佳的系统参数使时间常数最小化。并经多尺度微扰解析解得到稳定运动的条件。
Bio:
Prof. Chia-Ou Chang obtained the Bachelor and Master degrees from National Cheng Kung University on 1974 and 1976, respectively. After two-year military service and two-year work at Chung Shang Institute of Science and Technology, he was awarded a scholarship from the Department of mechanical Engineering, University of Iowa, on 1980 and got the Ph.D. on 1984. He was recruited and appointed as an associate professor in the Institute of Applied Mechanics, College of Engineering on 1984. He was nominated as the Vice-Head of the Staff-Cultivating Program of National Space Organization (NSPO) on 1991. On 1992, he was promoted to be a professor of this institute. When Prof. Yih-Hsing Pao was chosen as the 16th and 17th President of STAM (the Society of Theoretical and Applied Mechanics of the Republic of China), Chia-Ou was appointed as the Secretary General of STAM(1993-1994) . On January 2012, he was invited to give workshop on the thin shell theory and gyrscopic dynamics at National Sunchon University, South Korea, and to help them developing the related research program on the topics of HRG (hemispherical Resonant Gyroscope). Since August 2012, Dr. Chang has been appointed the Director of the Institute of Applied Mechanics, National Taiwan University. His major research interests are: dynamics, vibration, and control of structures, Analysis design, and micro-fabrication of micro-sensors and actuators.