A progressive approach to predict shot peening process parameters for forming integral panel of Al7050-T7451

In this paper, a progressive approach to predict the multiple shot peening process parameters for complex integral panel is proposed. Firstly, the invariable parameters in the forming process including shot size, mass flow, peening distance and peening angle are determined according to the empirical and machine type. Then, the optimal value of air pressure for the whole shot peening is selected by the experimental data. Finally, the feeding speed for every shot peening path is predicted by regression equation. The integral panel part with thickness from 2 mm to 5 mm and curvature radius from 3200 mm to 16000 mm is taken as a research object, and four experiments are conducted. In order to design specimens for acquiring the forming data, one experiment is conducted to compare the curvature radius of the plate and stringer-structural specimens, which were peened along the middle of the two stringers. The most striking finding of this experiment is that the outer shape error range is below 3.9%, so the plate specimens can be used in predicting feeding speed of the integral panel. The second experiment is performed and results show that when the coverage reaches the limit of 80%, the minimum feeding speed is 50 mm/s. By this feeding speed, the forming curvature radius of the specimens with different thickness from the third experiment is measured and compared with the research object, and the optimal air pressure is 0.15 MPa. Then, the plate specimens with thickness from 2 mm to 5 mm are peened in the fourth experiment, and the measured curvature radius data are used to calculate the feeding speed of different shot peening path by regressive analysis method. The algorithm is validated by forming a test part and the average deviation is 0.496 mm. It is shown that the approach can realize the forming of the integral panel precisely.     

应力为几何更新过程时结构可靠度

本文讨论应力为几何更新过程时结构可靠度，获得在设计基准期［０，Ｔ］内重复应力循环发生的次数服从几何更新过程时结构可靠度表达式。     

Ionospheric behavior of the F2 peak parameters foF2 and hmF2 at Hainan and comparisons with IRI model predictions

Monthly median values of foF2, hmF2 and M(3000)F2 parameters, with hourly time interval resolution for the diurnal variation, obtained with DPS-4 digisonde observations at Hainan (19.4°N, 109.0°E) are used to study the low latitude ionospheric variation behavior. The observational results are compared with the International Reference Ionospheric Model (IRI) predictions. The time period coverage of the data used for the present study is from March 2002 to February 2005. Our present study showed that: (1) In general, IRI predictions using CCIR and URSI coefficients follow well the diurnal and seasonal variation patterns of the experimental values of foF2. However, CCIR foF2 and URSI foF2 IRI predictions systematically underestimate the observed results during most time period of the day, with the percentage difference ΔfoF2 (%) values changing between about −5% and −25%, whereas for a few hours around pre-sunrise, the IRI predictions generally overestimate the observational ones with ΔfoF2 (%) sometimes reaching as large as ∼30%. The agreement between the IRI results and the observational ones is better for the year 2002 than for the other years. The best agreement between the IRI results and the observational ones is obtained in summer when using URSI coefficients, with the seasonal average values of ΔfoF2 (%) being within the limits of ±10%. (2) In general, the IRI predicted hmF2 values using CCIR M(3000)F2 option shows a poor agreement with the observational results. However, when using the measured M(3000)F2 as input, the diurnal variation pattern of hmF2 given by IRI2001 has a much better agreement with the observational one with the detailed fine structures including the pre-sunrise and post-sunset peaks reproduced reasonably well. The agreement between the IRI predicted hmF2 values using CCIR M(30,000)F2 option and the observational ones is worst for the afternoon to post-midnight hours for the high solar activity year 2002. During daytime hours the agreement between the hmF2 values obtained with CCIR M(30,000)F2 option and the observational ones is best for summer season. The discrepancy between the observational hmF2 and that obtained with CCIR M(30,000)F2 option stem from the CCIR M(3000)F2 model, which does not produce the small scale structures observed in the measured M(3000)F2.     

Kevlar/Nomex蜂窝夹层结构表面粘贴镀铜箔聚酰亚胺薄膜的工艺研究

文章对Kevlar面板Nomex蜂窝夹层结构表面粘贴镀铜箔聚酰亚胺薄膜的工艺进行了研究,分析了工艺特点、工艺流程、工艺难点,以及针对工艺难点所采取的工艺措施,最后根据产品的研制情况给出结论。     

尺寸参数对气动液阀启动特性的影响

为气动液阀的启动过程建立了数学模型，分析了尺寸参数对该阀启动特性的影响。计算结果表明：在保证必要的工作寿命的前提下，适当地增大控制腔气孔的直径或增大靠近控制腔的活塞端面直径有利于提高该阀的响应能力。本文所得的结论有利于此类阀门的设计。     

统计技术在复合材料制造过程中的应用

统计技术是质量管理中进行质量分析、质量控制和质量改进的重要工具。文章阐述了统计技术在复合材料过程控制中的应用，探讨了其应用范围、作用、办法及相关说明等内容。     

固体火箭发动机试验模态分析技术研究

将固体火箭发动机划分为144个自由度，采用锤击法，单点激励多点响应（SIMO）对其在4种工况下进行了频率响应的测量，应用了多种方法进行模态参数识别和数据拟合，并对其结果进行比较，获得了发动机在各工况1kHz以内的各阶固有频率、振型和阻尼，并对试验模态分析技术在固体火箭发动机试验中的应用进行了研究。     

4J32低膨胀合金的应用与切削加工及热处理

文中就4J32低膨胀合金在航天遥感器型号产品上的应用和切削加工及热处理进行了综述。分析了这种材料难切削加工的原因,并详细介绍了机械加工中采取的措施和工艺流程及具体的热处理方法。     

The fundamental parameters of the central stars of eight WR ring nebulae

We describe work that has recently been completed on deriving the fundamental parameters of eight WR stars through the photoionization modelling of their surrounding nebulae using non-LTE WR flux distributions. The resulting effective temperatures range from 57 000–71 000 K for the WN4-5 stars and <30 000–42 000 K for the WN6-8 stars. The derived stellar parameters are compared with those obtained from stellar emission line modelling. We find good agreement for the hot early WN stars, indicating that the non-LTE WR flux distributions have essentially the correct shape in the crucial far-UV region. We find lower temperatures for the four cooler late WN stars, particularly for the two WN6 stars. For the nebulae surrounding these stars, we find that the model flux distributions produce too much nebular ionization. We suggest that these discrepancies arise because of the lack of line-blanketing in the WR atmospheres. For the WO1 central star of G2.4+1.4, with strong nebular He II 4686 A emission, we derive a temperature of 105 000 K, somewhat less than previous estimates. The positions of our eight WR stars on the H-R diagram are compared with the evolutionary tracks of Maeder (1990) for solar metallicity. In common with previous workers, we find that our derived luminosities are too low, giving an initial mass range of 25–40 M, below that expected for the majority of WR stars.     

大迎角下导弹气动耦合控制系统分析

工程设计中，基于三通道自独立的前提来设计导弹控制器的常用方法，一般是将耦合项作为随机干扰来处理，这种方法不但具有一定的盲目性和不确定性，而且还丰厚明显的理论缺陷：耦合的存在改变了原系统的性能，严重时甚至会影响系统的稳定性。因此，只有当耦合影响很微弱时，这种方法才有实际应用价值。现分别从稳定裕度和气动参数两个方面，论述了气动交连耦合是造成大迎角飞行导弹控制系统不稳定的重要原因，并由此得出结论：对于大迎角下气动耦合强烈的导弹，其控制系统需考虑采用解耦控制，以便行这有效地变不稳定系统为稳定系统。