不同热处理合金钢JR阻力曲线的测定与分析

本文介绍JR阻力曲线的测定办法,并对不同热处理合金钢进行了实测。应用所得JR阻力曲线对合金钢的断裂韧度的评定表明了热处理工艺的影响。     

喷气燃料热氧化安定性对航空发动机燃油系统沉积物生成的影响研究

利用HiReTS试验机[1]模拟发动机燃油系统,对喷气燃料沉积物的生成进行了研究。试验结果表明:加入自行研制的高热安定性添加剂,可有效提高喷气燃料的热氧化安定性;使用提高热氧化安定性的喷气燃料可以显著减少燃油系统沉积物的生成,从而延长发动机的使用寿命。     

铝合金厚板时效成形回弹补偿算法

 时效成形是一种适用于飞机整体壁板零件制造的成形工艺,具有回弹量大的特点,因此需要在准确预测回弹量的基础上对模具型面进行修正,以消除回弹对成形精度的影响。本文提出了一种基于有限元计算驱动的适用于铝合金时效成形的模具型面迭代修正算法,并应用该算法进行了单曲率的圆柱面零件、双曲率的球面零件及马鞍形零件的修模计算分析。通过4次迭代计算,使圆柱面和球面零件成形误差减小到0.4 mm以内;通过5次迭代,使马鞍形零件除4个角部外,其余部位型面误差小于0.5 mm。证明了该回弹补偿算法具有计算精度高、收敛速度快的优点。     

固体火箭发动机多层结构壳体的导波频散特性分析

应用全局矩阵法,推导了多层结构壳体的导波频散方程,并分别针对固体火箭发动机四种不同层数的壳体导波频散曲线进行了求解,发现当结构层数和第一层厚度增加时,各模式曲线的间隔缩小．曲线数目增加,并有向零频方向靠拢的趋势。同时研究了粘接质量变化对频散特征的影响,随着胶层质量相对变差,频散曲线总体向左漂移。     

RS-GIS based morphometrical and geological multi-criteria approach to the landslide susceptibility mapping in Gish River Basin,West Bengal,India

Darjeeling Himalaya is one of the several mountainous areas of India which is often suffered from landslide hazards. In this paper, a multi criteria evaluation is applied using 16 morphometric indicators, geology and lineaments to identify the areas vulnerable in respect to drainage and relief conditions. As both drainage and relief parameters exert strong influences on landslide intensity, both the diversity maps are integrated for final landslide susceptibility mapping. The obtained results show that 20.17?sq.?km (7.61%) area within the basin is highly susceptible for landslides, where average drainage density is 3.78?km/sq.?km, relative relief is greater than 408?m and slope is greater than 12°. The validation result shows that very high landslide susceptible zone is associated with very high frequency of landslide occurrence. Beside this, ROC curve also suggests good predicted rate (86.60%) for the model. So, the proposed method can be applied for predicting landslide susceptible zone.     

复杂曲面逆向渐进成形方法的研究

复杂曲面逆向渐进成形的关键是如何确定渐进成形的运动轨迹。渐进成形的运动轨迹是按照成形件的等高线来进行加工的,传统的渐进成形是按照曲面已有的CAD模型,利用现有的后处理加工软件生成等高线加工轨迹进行加工。但由于复杂曲面没有已知的CAD模型或者已知的曲面方程,等高线图无法直接获得,因此,复杂曲面的逆向成形首先要解决等高线图的生成问题。本文通过对复杂曲面已知的离散点进行拟合获得曲面方程,从而得到逆向曲面的等高线图,并综合运用Java及MATLAB的编程优势对实物进行逆向CAD建模,由等高线图再编译成数控加工信息来完成复杂曲面的逆向渐进成形加工。文中给出了该方法的具体算法,并通过有限元数值模拟仿真实际曲面的逆向渐进成形验证了该方法的可行性。     

轧波胀形成形工艺应用研究

介绍了轧波成形+胀形的工艺过程、设备原理及技术改进.首先用轧波成形制出工件的大概形状,然后再用胀形工艺校圆.该成形方法不仅要求工装简单,而且成形精度较高,适用于旋转环形钣金零件.     

某型飞机桨叶平衡孔的喷丸强化技术分析

对飞机铝合金桨叶平衡孔的喷丸强化可以有效提高桨叶的疲劳强度。但在强化过程中必须对喷丸时间、喷丸强度、丸料、覆盖率等因素进行精确控制及优化，以确保达到理想的强化效果，保障飞行安全。     

Tribological evaluation of surface modified H13 tool steel in warm forming of Ti–6Al–4V titanium alloy sheet

The H13 hot-working tool steel is widely used as die material in the warm forming of Ti–6Al–4V titanium alloy sheet. However, under the heating condition, severe friction and lubricating conditions between the H13 tools and Ti–6Al–4V titanium alloy sheet would cause difficulty in guaranteeing forming quality. Surface modification may be used to control the level of friction force, reduce the friction wear and extend the service life of dies. In this paper, four surface modification methods(chromium plating, TiAlN coating, surface polishing and nitriding treatment)were applied to the H13 surfaces. Taking the coefficient of friction(CoF) and the wear degree as evaluation indicators, the high-temperature tribological behavior of the surface modified H13 steel was experimentally investigated under different tribological conditions. The results of this study indicate that the tribological properties of the TiAlN coating under dry friction condition are better than the others for a wide range of temperature(from room temperature to 500 C), while there is little difference of tribological properties between different surface modifications under graphite lubricated condition, and the variation law of CoF with temperature under graphite lubricated is opposite to that under the dry friction.     

超塑成型/扩散连接钛合金气动面表面沟槽对其强刚度的影响分析

超塑成形/扩散连接是一种先进的钛合金制造技术,采用该技术,4层结构的钛合金产品表面存在沟槽问题,对某气动面表面沟槽的成因和对强刚度的影响进行了浅析,评估了表面沟槽对该产品强刚度的影响水平.