考虑热物性变化的月壤温度数值模拟

探月设备的热分析设计依赖于真实有效的月面热环境信息。借助于ANSYS热分析模块,建立了月壤导热系数随密度和温度变化、热容随温度变化的变热物性月壤温度求解模型,分别计算了月面纬度为26°和赤道地区的月表温度,探讨了赤道地区浅层月壤的温度分布。其中,月表温度计算结果与实测数据良好的一致性表明计算模型和所用计算参数适用可靠;而通过修正月壤导热系数来提高计算结果与实测数据的吻合程度则部分展示了月壤温度计算理论;在探讨赤道地区浅层月壤的温度分布时,文章给出了不同时刻对应的月壤温度剖面和热流剖面,并适度分析了月壤内部热流和导热系数对月壤温度剖面的影响,这些为利用月壤的温度剖面规律进行探月设备的热控设计提供了理论支持。     

Fatigue life prediction model of 2.5D woven composites at various temperatures

As one of the new structural layout in the family of woven composites, 2.5D Woven Composites(2.5D-WC) have recently attracted an increasing interest owing to its excellent properties, i.e. high specific strength and fatigue resistance, in the aerospace and automobile industry. Indepth understanding of the fatigue behavior of this material at un-ambient temperatures is critical for the engineering applications, especially in aero-engine field. Here, fatigue behavior of 2.5D-WC at different temperatures was numerically investigated based on the unit cell approach. Firstly, the unit cell model of 2.5D-WC was established using ANSYS software. Subsequently, the temperature-dependent fatigue life prediction model was built up. Finally, the fatigue lives alongside the damage evolution processes of 2.5D-WC at ambient temperature(20 ℃) and unambient temperature(180 ℃) were analyzed. The results show that numerical results are in good agreement with the relevant experimental results at 20 and 180 ℃. Fatigue behavior of 2.5D-WC is also sensitive to temperature, which is partially attributed to the mechanical properties of resin and the change of inclination angle of warp yarns. We hope that the proposed fatigue life prediction model and the findings could further promote the engineering application of 2.5D-WC, especially in aero-engine field.