星用微热管电流辅助微弯曲成形机理及缺陷控制研究

With the development of the high density of microelectronics packaging in the small available spaces of modern micro-satellite, more heat flux would occur, causing the reliability reduction of the electrical devices in micro-satellite. Micro heat pipe of aluminum alloy with micro-grooves has many advantages in terms of high heat transfer capacity, good thermoresponsive ability, thin wall-thickness, light weight and high strength, which is widely used in the thermal control system of micro-satellite. However, the bending defect of bent micro-grooved heat pipes can weaken its heat transfer capacity. As a result, this project aims to study the micro-bending and bending defect control of micro-grooved heat pipes. A micro heat pipe bending method based on electrically-assisted (EA) local heating is proposed. Based on experiment, finite element analysis (FEA) simulation and modeling, bending defects during EA micro-bending of micro heat pipes will be studied in this project in terms of the size effect on defect, the influence of multiple fields / parameters coupled on bending defects as well as the modeling of Joule heating temperature and stress-strain distribution in bending area. Therefore, the defect control mechanism during micro-bending of micro heat pipes based on EA local heating will be uncovered. Finally, the EA micro-pending process for micro-grooved heat pipes of aluminum alloys will be conducted to obtain the optimum material/processing parameters, achieving the goal of high quality bending of micro heat pipes used in micro-satellite.

在新一代微型卫星中，大量微电子芯片被高度地集成在狭小空间内，导致热流密度急剧增加，星载系统可靠性降低。沟槽式铝合金微热管具有传热能力大、热响应快及壁薄质轻强度高等优势，被广泛地应用于微型卫星热控系统中。然而，微热管弯管加工时的缺陷削弱了其传热能力。因此，本项目以星用沟槽式微热管弯管成形及其缺陷控制作为研究对象，提出电流辅助局部加热弯管方法，利用实验研究、有限元模拟和理论建模相结合的方法，研究微热管电流辅助微弯曲成形缺陷尺度效应，探索多场耦合与多参数交互作用下微热管弯管缺陷的影响规律，建立微热管电流辅助微弯曲过程变形区温度与应力应变分布模型，揭示基于电流辅助局部加热的弯管缺陷控制机理，最后，开展星用沟槽式微热管电流辅助微弯曲工艺研究，获得最佳材料/工艺参数，实现微热管弯管的高质量可控制造。该项目将为微型卫星高度集成化后的热控难题提供研究基础和技术支持。

微型换热弯管作为一种高效的非能动传热构件被广泛应用于新一代微型卫星中，用来对高功率密度的星载微电子器件进行散热。然而，微型管弯曲成形缺陷削弱了其传热能力。因此，本项目提出了一种电流辅助局部加热微弯曲成形方法，研制了微型管电流辅助微绕弯成形装置，开展了微型管电流辅助微弯曲成形工艺研究，研究了电流作用下微型管弯曲成形缺陷尺度效应，建立了微型管电流辅助微弯曲成形有限元模型，分析了多物理场耦合多参数交互作用下的微型管弯曲缺陷影响规律。结果表明：本项目提出的微型管电流辅助微绕弯成形装置及方法，可在弯曲变形区（即弯曲模、定模和管坯相接触的切点附近）局部施加焦耳热，巧妙地解决了微型管无芯模弯曲截面畸变控制难题，特别适合微型管材如星载微热管等的随形弯曲。比如，管径5mm铝合金微型管以 10mm弯曲半径绕弯至 90°的同时向弯曲局部变形区施加100A/mm2的电流，相对于无电流辅助绕弯，微型管外侧壁仅减薄了约 3%，而截面畸变率降低了近 14%，实现了微型弯管的高质量可控成形，对推动电流辅助微成形技术在星载微型热控系统中的应用具有重要的社会效益和价值。