基于Mathimage组件的弹药装载效果仿真

基于Delphi Mathimage组件的弹药装载效果仿真系统用SQL Server2000提供数据库支持,Delphi7开发用户界面管理程序.先根据设置的坐标系原点和运载工具内部长宽高绘制运载工具,再按物资的左下角顶点坐标和长宽高绘制物资.根据数据库中车和物资的代码查出关联数据,通过装载仿真模块显示每辆车的装载情况.     

十字形试件双向拉深试验系统建立及加载精度分析

为了研究复杂加载路径下板料塑性变形行为 ,建立了十字形试件双向拉深试验硬件与软件系统 ,实现了同轴两夹头的位移同步控制 ,位移和载荷的比例加载与非比例加载控制 ,以及根据载荷变化判断加载停止的控制等关键技术。试验验证表明 ,所建系统具有较好的准确性和可靠性 ,为进一步研究提供了试验基础。     

考虑载荷交互作用的蠕变损伤累积和剩余寿命估算

提出两级加载条件下考虑加载历史影响的蠕变损伤演变方程和剩余寿命估算方法,分析结果表明,高一低加载时,由于硬化严重,损伤演变速率减缓,使寿命分数之和大于1;而在低一高加载时,由于硬化较弱,引起损伤演变速率加速,使寿命分数之和小于1。受损材料的硬化状态对后续载荷下的损伤演变过程具有明显的影响,本文方法反映的加载顺序效应与试验观察一致。     

Loading rate effect on the mechanical behavior of brittle longmaxi shale in nanoindentation

Understanding the properties of sedimentary rock shale is critical for wellbore stability and hydraulic fracturing design in unconventional shale gas extraction. The mechanical properties of shale are a function of various environmental factors, such as stress, temperature, saturation and loading rate. Thus, in this study, the loading rate effect on the mechanical behavior of shale using nanoindentation was investigated. Nanoindentation tests were performed at a peak load of 500 mN and loading rates of 5–30 mN/s. In addition, X-ray diffraction (XRD) analysis was performed to identify the composition of the selected shales, and reveal the target sample is brittle. Scanning electron microscopy (SEM) analyses were performed to determine the surface morphology and demonstrate the existence of pile up and sink-in events. The results of the nanoindentation study indicate that the material behavior of rock depends on the loading rate at the nanoscale: with the increase in the loading rate, the contact hardness, Young's modulus, yield stress and indentation shear stress gradually increase. However, final penetration depths, the contact penetration depths, the maximum penetration depths and the contact stiffness decrease with increasing loading rates. Pop-ins were imperceptible at both the low and high loading rates, reflecting that the shale is brittle. Comparison of the pressure hardening coefficient in the elastic–plastic yield criterion model and the strain hardening coefficient in the strain rate sensitivity model indicates that shale is more sensitive to pressure hardening than strain hardening. A discussion regarding the uncertainty of evaluating the mechanical properties via nanoindentation indicates that the contact surface determination and the loading rate control are both critical to obtain a meaningful value for the mechanical parameters.     

新型油槽车定量装车工艺计算研究

根据新型油槽车定量装车系统中鹤管分布不同的工艺特点, 建立了满足传统油槽车装车时间要求的 油槽车定量装车时间的数学模型。讨论了新型油槽车定量装车系统水力计算的数值求解方法, 应用数学迭代的方 法求解管路系统计算方程, 求解出集油管、 鹤管段的流量。应用 VC++6. 0高级语言编制了定量装车系统的计算程 序, 求得了各鹤管流量, 进而求出装车时间。该数学模型可用于油槽车定量装车系统的设计、 改造和运行管理, 为计 算、 分析、 优化和运行管理等环节提供理论支撑。     

轴颈油膜压力简化加载方式探讨

对曲轴连杆轴颈油膜压力的简化加载公式重新进行了推导,指出了以前加载公式的不足之处,给出了新的简化加载公式。通过简化的单拐曲轴的有限元计算验证了新加载公式的正确性,并分析了旧的简化加载公式给曲轴强度计算带来的不利影响。     

Effects of Loading Rate and Duration on Axial Behavior of Concrete Confined by Fiber-Reinforced Polymer Sheets

In this study, 18 concrete cylinder specimens were tested either under uniaxial compression at different loading rates or exposed to sustained axial stresses after being jacketed externally with carbon-fiber-reinforced polymer (CFRP) sheets. The specimens were cast using medium strength concrete. All the specimens had identical dimensions and level of confinement. Loading rate and applied sustained stress level were the main test parameters. Applied loading rate varied between 0.0002 and 0.04 strain/min. Four stress levels between 0.52 and 0.85fcc′ (0.90 and 1.46fco′) were used in short-term creep tests. Test results showed that the stress-strain behavior of CFRP confined concrete was influenced by the change in loading rate, and CFRP confinement provided considerable increase in the creep performance of concrete. The strength enhancement was more pronounced for specimens loaded at higher strain rates, while specimens loaded at slower strain rates exhibited better deformability. Results obtained from short-term monotonic loading tests were also compared with the results of two analytical approaches originally developed for plain concrete. None of the specimens failed during the short-term creep tests. However, the lifetime of the specimen, which was subjected to 0.85fcc′ (1.46fco′) sustained axial stress, was predicted as 20 days. Results of residual strength tests showed that specimens did not have any strength loss due to sustained loading.     

Identification of tidal and climatic influences within domestic radon time-series from Northamptonshire, UK

Analysis of data from extended radon concentration time-series obtained from domestic and public-sector premises in the vicinity of Northampton, UK, and elsewhere, confirms that, in addition to the generally recognised climatic influences, 'Earth Tides' and 'Ocean Tidal Loading' drive periodic radon liberation via geophysically driven groundwater level variations. Regression and cross-correlation with environmental parameters showed some degree of association between radon concentration and mean temperature and rainfall. Fourier analysis of radon time-series identified periodicities of the order of 23.9 h (luni-solar diurnal, K(1)), 24.0 h (solar day, S(1)), 168 h (1 week) and 661.3 h (lunar month, M(m)), while cross-correlation with tidal strength demonstrated periodicity of the order of 14 days (lunar-solar fortnight, M(f)). These results suggest that astronomical influences, including tides, play a part in controlling radon release from the soil.     

自平衡加载法试桩探讨

详细地介绍了桩的自平衡加载试验方法及对试验结果的分析 ,提出了试桩中应注意的问题。     

负载金属基活性炭纤维对一氧化氮和一氧化碳的吸附及催化性能研究

采用浸渍法制备了铯和铜化合物为主的系列金属基活性炭纤维,用气相色谱等手段对所制金属基活性炭纤维对一氧化氮和一氧化碳的吸附和催化性能进行研究,实验结果表明：负载二价铯的活性炭纤维对一氧化碳有突出的吸附能力,附着铯载负量增大,样 对一氧化碳的吸附容量增加,动态吸附穿透时间延长,采用铜／铯混合物负载经用单组份铯可提高对一氧化碳的动态吸附效率,节省铯的用量,经４００℃热处理的负载铯活性炭纤维在物负载比用的