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SCR技术制备A2017半固态材料及其触变性能的研究 总被引:3,自引:0,他引:3
单辊搅拌技术 (SCRShearing/CoolingRollProcess)技术制备的A2 0 17半固态材料比常规铸造坯组织优良 ;SCR技术制备的A2 0 17半固态材料在 5 30~ 5 70℃范围内 ,可以进行触变成形 ;半固态成形平均屈服强度比热加工时的屈服强度低 10MPa ;A2 0 17半固态材料触变过程分为四个阶段 ,稳定触变阶段A2 0 17半固态材料的触变性能稳定 ,半固态加工时容许的最大加工变形范围为 6 4 %~ 72 %。 相似文献
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农林飞机通常在3-5m的超低空进行作业飞行,在离地面3m以上的空中往往会有树木、电线杆、电线、堤坝、土堆、山丘、建筑物等障碍物,稍有不慎,就有与之撞击的可能。这样的工作条件除要求飞机具有良好的超低空飞行性能以外,还要求飞机具有一定的耐坠撞能力。本文针对农林飞机执行任务过程中可能发生的碰撞、坠毁等特点,研究了农林飞机抗坠毁设计技术、计算分析仿真技术。 相似文献
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针对某机全机主操纵系统疲劳试验中动态操纵情况下的应变测量以及试验载荷监控问题进行了分析和讨论,并对基于应变测量数据分析的操纵系统疲劳试验载荷监控方法的确定及其应用效果进行了阐述。在操纵系统疲劳试验过程中的实际监控结果表明,该方法对副翼/平尾/方向舵操纵系统多种试验状态下的试验载荷监控实用有效。 相似文献
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反射面天线的双站雷达截面 总被引:1,自引:0,他引:1
本文导出了任意旋转反射器天线在任意双站角的散射场和雷达截面(RCS),其中反射场由几何光学法(GO)求得,绕射场则利用基于物理绕射理论(PTD)与等效线电流辐射积分公式导出的等效电磁流法求得。分别计算了轴向入射和偏轴向入射时在任意散射方向上水平极化与垂直极化两种情况下的双站RCS,并给出了这些结果的立体图形式。方法简化为单站情况时的计算结果与实验值大致相符。 相似文献
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To obtain high-quality aviation forgings of titanium alloys, b forging is an essential processing step which must be considered throughout a production process. In this work, the effect of b forging on the crystal orientation and morphology of lamellar a was experimentally investigated in a two-phase titanium alloy. Strong dynamic recovery during b working resulted in the formation of low-angle grain boundary(LAGBb) inside b grains. The lamellar a can penetrate through the LAGBb, leading to similar intra a LAGBs on subgrain boundaries. Deformation banding occurs at high strain rates, and both diffusive and sharp boundaries of deformation bands can be observed.A continuous change of the b orientation in diffusive boundaries results in the formation of fine and disordered a lamellae without intra-lamellar boundary to hold the Burgers orientation relationship(OR). On sharp boundaries, it is prone to producing continuous grain boundary a(aGB) with a highly similar orientation along the boundaries. Meanwhile, there may exist several lower-angle boundaries within the grain boundary a for a smoother orientation change on the b grain boundary. 相似文献
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Yunfei Xiang Jianping Yue Kai Tang Zhen Li 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(1):103-117
The 2016 Mw 6.0 Italy earthquake is successfully recorded by the near-field 10?Hz GPS and 200?Hz Strong Motion (SM) stations, providing valuable data for this study. A comprehensive study of this earthquake is carried out based on GPS data, which contains coseismic deformations analysis, noise analysis, seismic wave picking, and magnitude determination. The noise of most GPS-derived displacement waveforms can be described as a combination of white noise, flicker noise, and random walk noise after the earthquake occurrence, and the spectral indices vary significantly for most stations, implying that the seismic signals have affected the noise characteristic of GPS-derived displacement waveforms. S-transform is employed to assess the GPS capability to detect the seismic arrival time. The SM station AMT and the GPS station AMAT are in good agreement in seismic wave picking, and the difference is only 1.2?s in the north component, suggesting that the outcome of seismic wave picking using GPS data is reliable. Then, a classic empirical formula is employed to determine the moment magnitude. A robust moment magnitude (Mw 5.90) can be estimated by the nine GPS stations with about 23.9?s. If four GPS stations near the epicenter is chosen to determine the magnitude, it only take 13.0?s to retrieve a reliable preliminary (Mw 5.82) magnitude, which is 5.4?s ahead of nine stations. In addition, Cross Wavelet Transform (XWT) is adopted to measuring the correlation and phase relationship between GPS and SM records. The result of XWT analysis indicates 10?Hz GPS is capable of capturing reliable and accurate coseismic dynamic deformations, as evidenced by the XWT-based semblance being close to 1 between GPS and SM records. The above results confirm the capability of 10?Hz GPS to capture coseismic dynamic deformations, detect seismic arrival time, and determine earthquake magnitude. Moreover, rapid magnitude determination based on 10?Hz GPS data can be regarded as an important supplement to Earthquake Early Warning (EEW). 相似文献