管路多源激励动响应分析及减振优化设计

通过建模软件与有限元软件联合仿真技术,研究了某航天发动机管路的固有特性,对发动机管路的有限元模型进行模态分析,在其基础上对受到多源随机振动激励下的管路结构两端施加不同载荷,进行随机振动分析,得到其薄弱环节。提出了以减振为目标的空间管路优化设计方法,对管路进行参数化建模,且对其参数化部分进行结构优化。优化后管路前3阶固有频率避开原频率为20%以上、动响应减小18.02%,管型优化成功。

ZD029高速点胶试验平台动态分析及结构优化

点胶技术及其装备快速的发展,逐步取代了许多传统的固接方式,特别是在3C、电子封装等相关产业中起到越来越重要的作用。设计了一台ZD029高速点胶平台,采用ANSYS软件对平台整机进行了动态分析,并对支撑件床身、立柱,以及高速运动部件横梁、溜板和滑板进行拓扑结构优化,优化后的床身、立柱、横梁、溜板和滑板质量分别减少了9%、3.7%、11.5%、4.5%和2.4%,平台整机质量减少了7.5%左右,整机1阶固有频率有所提高。振动激励源分析表明,平台点胶工作频率低于84 Hz时,整机不会出现共振情况,但要满足更高频率点胶技术要求,平台需在结构上进一步优化,提高其抗振性能。为高速点胶平台结构的进一步优化提供了依据。

Numerical modeling of the 2D time-domain transient electromagnetic secondary field of the line source of the current excitation

To effectively minimize the electromagnetic field response in the total field solution, we propose a numerical modeling method for the two-dimensional （2D） time- domain transient electromagnetic secondary field of the line source based on the DuFort- Frankel finite-difference method. In the proposed method, we included the treatment of the earth-air boundary conductivity, calculated the normalized partial derivative of the induced electromotive force （Emf）, and determined the forward time step. By extending upward the earth-air interface to the air grid nodes and the zero-value boundary conditions, not only we have a method that is more efficient but also simpler than the total field solution. We computed and analyzed the homogeneous half-space model and the fiat layered model with high precision--the maximum relative error is less than 0.01% between our method and the analytical method--and the solution speed is roughly three times faster than the total-field solution. Lastly, we used the model of a thin body embedded in a homogeneous half-space at different delay times to depict the downward and upward spreading characteristics of the induced eddy current, and the physical interaction processes between the electromagnetic field and the underground low-resistivity body.