Combined and interactive effects of interference fit and preloads on composite joints

The combined and interactive effects of the bolt-hole fit conditions and the preloads of the fasteners on the load carrying capacity of single-lap composite-to-titanium bolted joints have been investigated both experimentally and numerically. Quasi-static tests of the hybrid joints with different fit conditions are implemented, and a three dimensional finite element progressive failure analysis model is proposed to predict the influences of the bolt-hole fit conditions and fastener＇s pre- loads on the mechanical behaviors of the joints. Based on the experimental validated simulation method, a multi-factor, mixed levels orthogonal design table and the analysis of variance method are used to arrange the simulation conditions and to further study the interactive effects of preloads and fit conditions. Through the analysis of the results, for the researched double bolt, single-lap composite-titanium joints, it is found that： the effects of both the interference fit and the preloads change from positive into negative mode with the increase of the interference fit values or preload values; appropriate bolt-hole fit conditions and preloads can improve the bolt-hole contact conditions of the loaded joints, and then retard the fiber failures around the fastener holes, and increase the load carrying capacity of the joints eventually; the interactive effect of the bolt-hole interference fit conditions and preloads cannot be ignored and the parameters need to be considered together and synthetically as the joints are being optimized.     

两级并联式地空导弹分离特性分析

针对两级并联式地空导弹分离过程，分析了分离过程中可能出现的问题，指出了并联导弹自动分离条件，并针对某并联导弹具体设计情况，讨论了分离特性计算分析的几个方面，给出了一种计算分离力的简便方法，并结合某导弹实际设计情况对其进行了计算，对其结果进行了分析讨论。     

最大攻角达80°时尖拱柱模型亚音速实验结果的初步讨论

在ＦＤ－０８风洞中，为了解采用侧壁支撑机构进行大攻角实验的可能性，进行了头部长细比３．５尖拱柱模型的亚音速实验，最大攻角达８０°。本文通过与Ａｍｅｓ１２英尺风洞实验结果的比较，介绍了实验结果并对实验结果作了初步讨论。     

石英晶体压力传感器的研制及其应用

本文介绍了应用广泛的石英晶体压力传感器的结构、安装、标定和使用。该压力传感器具有结构小、重量轻、抗振动耐腐蚀和性能稳定、工作可靠、寿命长等优点。文中提供的自行设计的FcCY_4-1B石英晶体压力传感器,通过在航天与航空发动机上的试验考核,证明其精度、灵敏度、频响范围和可靠性等指标均达到国内先进水平。     

液体二次喷射的时间响应特性

本文着重分析了液体二次喷射系统从指令信号到产生侧向力各环节的时间滞后特性,介绍了二次喷射侧向力时间响应特性的试验研究。试验结果表明,侧向力的产生相对于喷射活门开启的纯滞后时间为4毫秒左右,与理论分析的预计值基本相符。此外,还获得一些有价值的试验结果,为导弹飞行的稳定性分析提供了试验依据。     

洛氏硬度计试验力误差对C标尺示值的影响

阐述初、主、总三种试验力误差对洛氏 C标尺高、中、低值的影响以及单方面地用调整块调整时所出现的必然现象。