基于ProCAST的ZL114A尾段壳体凝固成形数值模拟与工艺优化

目的 针对ZL114A尾段壳体研制需求,利用低压充型液态成形工艺与数值仿真计算,预测疏松缺陷分布位置及严重程度,通过改进工艺来减少疏松缺陷,进而提高生产合格率。方法 基于ProCAST软件对ZL114A尾段壳体低压充型凝固过程进行仿真计算,分析充型凝固过程中的流动场与温度场分布、充型时间、流动长度与凝固时间,预测疏松缺陷分布位置及严重程度,结合枝晶相干点双电偶热分析法测试结果,对低压充型工艺进行设计优化。结果 由尾段壳体凝固疏松缺陷的仿真计算结果与枝晶相干点温度测试结果可知,低压充型增压速度得到提高,保压时间有所延长,对安装凸台冷铁材质与厚度进行设计优化后,疏松缺陷得到显著改善。结论 通过数值仿真计算指导了铸造工艺设计,制备得到了满足技术指标要求的ZL114A尾段壳体。     

航空检测设备设计要素

随着电子技术在航空领域的应用,机载系统设备日趋复杂,其故障也随之增加.为提高维修效率,广泛应用机内自检BIT(built in test)技术,多数故障飞机自身就可以定位,不再需要传统的故障检测设备.但由于机载设备的复杂化,系统指标测试突显出来,对检测设备提出了新的要求.结合实例分析了BIT飞机配套检测设备的功能设置、...     

碳纤维及树脂基复合材料产业发展面临的机遇与挑战

本文介绍了国内外高性能碳纤维、碳纤维增强树脂基复合材料、复合材料制造技术等发展现状及未来发展趋势,总结了国内碳纤维增强树脂基复合材料产业发展存在的问题,分析了国内碳纤维增强树脂基复合材料产业发展的需求,提出了碳纤维增强树脂基复合材料重点发展方向。      

压弯半径对7A85结构壁板退火展平成形尺寸与组织性能的影响研究

目的 为满足结构舱段用高强高韧铝合金宽幅薄壁高筋整体成形壁板的精密制备需求，在材料退火组织状态下，结合不同压弯半径展平工装，实现7A85结构壁板的展平处理。方法 采用ABAQUS有限元软件计算不同压弯半径下的结构回弹尺寸，采用万能力学性能试验机测试不同区域的力学性能，结合扫描电镜完成组织形貌与断口形貌的观察。结果 随着压弯半径的增大，7A85铝合金结构壁板蒙皮区域的应力峰值持续下降，结构回弹尺寸误差先下降后上升，立筋区域的应力峰值持续下降，结构回弹尺寸误差先下降后上升。当FSW加厚区进行压弯时，随着压弯间隙的增大，应力峰值持续下降，随着压弯半径的增大，应力峰值先上升后下降，结构回弹尺寸误差明显提高。结论 结合7A85铝合金挤压圆筒不同区域金属型退火展平模具，成功制备出了幅长为8 000 mm、幅宽为1 280 mm的7A85铝合金结构壁板。     

Assessment of temperature distributions based on the Adaptive Cross Approximation

During the production process of rolled steel plates quality control plays an important role. The temperature distribution in the plate, which is determined with a temperature measuring device, has to be assessed on homogeneity. The temperature data is stored in a rectangular array. A real-time assessment is required. A new method, the Adaptive Cross Approximation (ACA) for the temperature assessment is proposed. The ACA-method is applied to a two-dimensional rectangular temperature array. The temperature array as a result of measurements contains a stochastic measuring tolerance. Nevertheless, the temperature field, which is usually a full matrix, can be approximated by a series of low rank matrices according to the ACA-method. The number of iteration steps is used as the criterion on homogeneity. Numerical examples, based on real industrial data, illustrate the efficiency of the ACA-method. In most cases, the subjective human evaluation of temperature fields matches with the assessment made by the ACA-method. Furthermore, the ACA-method leads to a significant compression of the temperature arrays and can be also used for archiving of the measured data almost without loss of information.     

一种复合材料低速冲击性能的简化预计方法

低速冲击引起的分层损伤是层合板的主要损伤模式。对分层损伤进行数值模拟有着重要的工程价值,合理的假设有助于问题的简化,对于计算量和计算精度有着重要的影响。本文研究了层合复合材料分层损伤分析模型的建模方法,基于三个基本假设建立了分析模型,采用LS-DYNA显式算法对层合板的冲击响应和分层损伤进行了计算,计算结果与实验结果的一致性证明了该方法的正确性。     

Effect of Al3Zr particles on hot-compression behavior and processing map for Al-Cu-Li based alloys at elevated temperatures

The influence of Al₃Zr particles on the hot compression behavior and processing map (PM) of Al-Cu-Li based alloys under isothermal plane-strain compression in the temperature range of 400-500 °C and at the strain rates of 0.01-10 s^-1 was investigated. The corresponding microstructure was analyzed using optical microscopy (OM), electron back-scattered diffraction (EBSD) and transmission electron microscope (TEM). The results showed that dynamic recovery (DRV) played a greater role than dynamic recrystallization (DRX) in dynamic softening. At low temperatures, the Al₃Zr particles were the significant barriers to inhibit DRV and DRX grain growth. When the temperature reached 500 °C, the Al₃Zr particles readily spread along grain boundaries just like a necklace due to the dissolution of Al₃Zr particles and rapid diffusion of Zr through grain boundary, resulting in generating the macroscopic cracks and forming an instability domain at 490-500 °C, 0.01 s^-1 in the PM.     

航空装备软件可靠性参数研究

开展航空装备软件可靠性参数研究是进行航空装备软件可靠性工程的基础。首先从软件可靠性定义入手，阐述了参数选取的原则；最后提出了针对不同类型的航空装备软件可靠性参数。     

微机械谐振子单端口电容检测方法研究

针对微机械谐振子电容信号难以检测的问题,本文采用基于频域分离的单端口静电激励／电容检测方案,并配合以隔离变压器应用技术。这种检测方式时域连续,除此,单端口检测既简化了谐振器结构,又避免了双端口检测中激励信号与检测信号存在耦合干扰的问题。实验结果表明：所设计的方案可以有效观测到梁的谐振现象并解算出谐振子的振动信息,为下一步实现单端口谐振子的闭环奠定了基础。