热防护结构高温合金蜂窝板的力学性能研究

发布时间：2019-05-11 08:04

【摘要】：金属热防护结构起着保护飞行器免受高温过热的重要作用,其最外层通常为具有重量轻、比强度高、隔热性能好等特点的高温合金蜂窝板,由于飞行器工作过程中会承受复杂的载荷变化,蜂窝板也必须具有更好的承压性能才能使热防护结构稳定的工作,因此研究蜂窝板在不同载荷下的面外压缩性能具有重要意义。首先本文以镍基高温合金材料为基材,通过辊压成型和校形制备出无明显缺陷的瓦楞板,在研究了箔材点焊性能最佳参数的基础上,利用电阻点焊工艺将瓦楞板连接成蜂窝芯,在对芯体进行线切割、平磨加工、清洁处理后,与面板通过真空钎焊技术连接在一起形成完整的蜂窝板。其次,对制备好的蜂窝板进行静态平压试验和分离式霍普金森杆动态冲击试验,比较分析了两种不同面外载荷下蜂窝板的变形过程与屈服应力,在平压与冲击下蜂窝板的变形阶段基本相同,应力-应变变化趋势相似。在动态冲击试验中,发现蜂窝板的应变率和屈服应力随着冲击子弹速度的增加而变大,表明蜂窝板是一种率相关结构,造成率相关性的原因在于材料的率相关性和蜂窝板特殊的柱形结构。最后,利用ANSYS/LS-DYNA软件模拟蜂窝板平压和冲击性能试验,在平压中,应力首先集中在芯壁中间位置,然后向外扩展,在冲击中先是蜂窝芯所有部分应力增大,然后应力才集中在芯壁中间。平压模拟中,蜂窝板的屈服强度随芯壁厚度的增加有明显提高,屈服强度随芯体高度的增加先是提高然后下降,而且芯壁厚度比芯体高度对蜂窝板平压屈服应力的影响更加明显。
[Abstract]:Metal thermal protection structure plays an important role in protecting aircraft from high temperature overheating. Its outermost layer is usually a superalloy honeycomb plate with the characteristics of light weight, high specific strength and good thermal insulation, etc. Because the aircraft will bear complex load changes in the working process, the honeycomb plate must also have better pressure performance in order to make the thermal protection structure stable, so it is of great significance to study the out-of-plane compression performance of the honeycomb plate under different loads. In this paper, the corrugated plate without obvious defects is prepared by roll forming and proofreading based on nickel-based superalloy. On the basis of studying the optimum parameters of spot welding performance of foil, the corrugated plate is connected into honeycomb core by resistance spot welding process. After wire cutting, flat grinding and cleaning of the core, the honeycomb plate is connected with the panel by vacuum brazing technology to form a complete honeycomb plate. Secondly, the static flat pressure test and split Hopkinson bar dynamic impact test were carried out on the prepared honeycomb plate, and the deformation process and yield stress of the honeycomb plate under two different out-of-plane loads were compared and analyzed. Under flat pressure and impact, the deformation stage of honeycomb plate is basically the same, and the change trend of stress-strain is similar. In the dynamic impact test, it is found that the strain rate and yield stress of the honeycomb plate increase with the increase of the impact bullet speed, which indicates that the honeycomb plate is a rate-dependent structure. The correlation of formation rate is due to the rate correlation of materials and the special cylindrical structure of honeycomb plate. Finally, the ANSYS/LS-DYNA software is used to simulate the flat pressure and impact performance of the honeycomb plate. In the flat pressure, the stress is first concentrated in the middle of the core wall, and then expands outward. In the impact, the stress of all parts of the honeycomb core increases, and the stress of the honeycomb core increases in the middle of the core wall. Then the stress is concentrated in the middle of the core wall. In the flat pressure simulation, the yield strength of the honeycomb plate increases obviously with the increase of the core wall thickness, and the yield strength increases first and then decreases with the increase of the core height. Moreover, the thickness of the core wall is more obvious than the height of the core body on the flat compression yield stress of the honeycomb plate.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG132.3

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