基于储存寿命的战储器材轮换方法研究

针对传统轮换方法在战储器材轮换上的缺陷和不足,结合长储器材失效数据较少、无法实时检测等特点,提出了一种利用定期检测数据分析小子样储存可靠度,并估计其储存寿命来确定轮换期的方法。在求解寿命分布参数时,为克服迭代法运算时间较长、初始值选取对迭代结果收敛性影响较大等不足,利用粒子群算法求解。通过实例分析表明,该方法得到的结果与工程实际相吻合,能为战储器材的轮换提供有效的决策支持。     

一种基于测试数据的单枚导弹贮存寿命评估方法

目的研究单枚导弹的贮存寿命评估问题。方法对导弹状态数据中的定期测试数据进行统计分析,确定测试数据的变化规律,并通过移动标准差概念的引入,探讨测试数据的稳定性。应用多项式最小二乘法拟合对测试数据中表征导弹关键部件的特征参数的移动标准差进行预测。建立了单枚导弹的贮存寿命评估模型,并进行实例分析。结果得出了导弹的贮存稳定性水平。结论验证了该评估模型的合理性。     

Study on machinability of a stellite alloy with uncoated and coated carbide tools in turning

Stellite alloys, which have been widely used in the aerospace, automotive and chemical industries, are hard-to-cut cobalt-based materials. This study investigates the machinability of stellite 12 alloys with uncoated carbide cutting tool grades YG610 (K01-K10) and YT726 (K05-K10/M20) and SANDVIK coated carbide tool SNMG150612-SM1105 under dry cutting conditions. Both wear mechanisms and failure modes of the uncoated and coated tools were investigated with turning experiments. The results show that the coated tool SM1105 remarkably outperforms the uncoated tools; and the cutting tool YG610 generally outperforms YT726 under all cutting conditions. Built-up edge was found with YG610 in some cutting conditions and with SM1105 at cutting speed of 16 m/min. Tool surface burning marks were observed on YT726 at relatively higher cutting speeds. Wear develops slowly with coated tools SM1105 until VB reaches 0.2 mm at most conditions (except at v = 43 m/min, f = 0.25 mm/r). Excessive tool flank typically resulted in tool breakage at the cutting edge for uncoated tools. Abrasive and adhesive wear of cutting tools were observed at low cutting speeds while diffusion and chemical wear occurred at higher cutting speeds.     

Effect of fluid concentration in titanium machining with an atomization-based cutting fluid (ACF) spray system

The aim of this work is to investigate the effect of metal-working fluid (MWF) concentration on the machining responses including tool life and wear, cutting force, friction coefficient, chip morphology, and surface roughness during the machining of titanium with the use of the ACF spray system. Five different concentrations from 5 to 15% of a water-soluble metalworking fluid (MWF) were applied during turning of a titanium alloy, Ti–6Al–4V. The thermo-physical properties such as viscosity, surface tension and thermal conductivity of these concentrations were also measured. The test results demonstrate that the tool life first extends with the increase in MWF concentration and then drops with further increase. At low concentration (e.g., 5%), a lack of the lubrication effect causes to increase in a higher friction at the tool–chip interface resulting in severe chipping and tool nose/flank wear within a short machining time. On the other hand, at high concentration, the cooling effect is less. This increases cutting temperature and a faster thermal softening/chipping/notching of the tool material and higher friction at the tool–chip–workpiece interaction zones resulting in early tool failure. A good balance between the cooling and the lubrication effects seems to be found at the 10% MWF concentration as it offers the best machining performance. However, machining with flood coolant is observed to perform the best in the range of 5–7%.     

实测/预测辽河铬(Ⅵ)水生生物基准与风险评估

该研究对辽河流域重金属铬(Ⅵ)的水生生物毒性数据进行搜集与筛选,推导辽河流域铬(Ⅵ)的水生生物基准值,并对辽河流域25个采样点位采集水样,测定铬(Ⅵ)的环境暴露浓度,最后对辽河流域水生生物铬(Ⅵ)暴露的潜在风险进行评估.此外,采用美国环境保护署(US EPA)物种种间关系估算模型(ICE)对辽河流域物种毒性值进行预测,并对基于预测毒性值的水生生物基准进行推导.结果表明,辽河流域基于实测毒性数据的水生生物急性基准值(CMC)为17.73μg·L-1,慢性基准值(CCC)为12.15μg·L-1;ICE模型预测的辽河流域生物毒性值推导的CMC值为13.97μg·L-1,实测CMC值与预测值比较接近,表明ICE模型可应用于水生生物基准值的预测.铬(Ⅵ)的水质分析结果表明25个采样点位水体铬(Ⅵ)浓度较低,均达到GB 3838-2002地表水质标准中铬(Ⅵ)的Ⅰ类或Ⅱ类标准,水质状况良好;然而,在对水生生物的潜在风险方面,通过生态风险评估得出7月辽河流域25个点位中环境暴露值超过慢性基准CCC值的有7个,12月超过慢性基准CCC值的有6个,表明辽河流域个别点位铬(Ⅵ)暴露可能会对水生生物产生不可接受的风险.     

一种高可靠电子产品贮存寿命评估方法

介绍了加速寿命试验的基本理论,并给出一种基于多应力加速试验的高可靠电子产品贮存寿命评估方法。首先给出一种基于多应力加速试验的电子产品贮存寿命评估流程,然后指出关键环节是根据产品特点选择合适的加速应力、加速模型,最后给出数据处理方法。该评估方法经过了工程实践,快速评估出一种高可靠产品的贮存寿命。     

基于瞬态分析的浮动核电站高能管路冲击疲劳寿命评估

目的合理评估浮动核电站高能管路在水下冲击载荷下的疲劳寿命。方法开展高能管路静载、模态和瞬态响应分析,得到管路在水下冲击作用下的应力时程曲线,为管路疲劳寿命估算提供基本应力谱输入。基于冲击疲劳损伤模型,运用nCode疲劳分析软件,估算管路的冲击疲劳寿命。结果管路在一次冲击载荷作用下会经历多次应力循环,最大应力值超过材料屈服极限的11%。管路在横向冲击作用下的冲击疲劳寿命为3.95×10~4次。结论管路在冲击载荷作用下的最大应力响应发生在冲击输入的正向三角波之后,反向三角波之内,是由于惯性效应造成的响应滞后现象。管路固定端、弯头和三通是应力集中区域,管路疲劳破坏一般发生在这些局部区域。     

基于Arrhenius模型的汽车电子产品加速寿命试验设计分析

目的对Arrhenius模型的基本方程进行分析,为评估产品热应力水平提供试验设计方法。方法推导寿命周期中多个温度点的加速因子和加速寿命试验时间,并计算其等效温度点与寿命周期中各点温度和时间的关系,得出等效温度的计算公式。结果根据汽车电子产品温度的正态分布规律,计算等效温度点曲线,作为汽车电子加速寿命试验的输入,通过算例说明与传统试验方法的差异性。结论等效温度点法比传统试验方法更适应于各种温度分布,可以更准确地评估产品热应力水平。     

纯电动与柴油货车全生命周期能耗及排放分析

选择传统柴油厢式货车和纯电动厢式货车为研究对象.基于GREET软件,建立适宜于我国国情的车辆全生命周期计算模型,对比分析两款车型全生命周期的能耗、温室气体排放以及标准污染物排放情况;结果表明:纯电动货车全生命周期内的百公里能耗比柴油货车降低了6.57%,化石燃料、天然气、石油的百公里消耗量分别降低14.4%、58.8%、96.8%;纯电动货车CH_4、VOC、CO、NO_x的排放分别比柴油货车低16.7%、14.8%、63.0%和63.4%,而柴油货车的CO_2和SO_x的排放量比纯电动货车低7.2%和96.8%.同时对车辆进行不确定性分析和单因素的敏感性分析发现,纯电动货车全生命周期内CO_2排放量对电能生产阶段的敏感度高达66.9%,而且相较于柴油货车,纯电动货车在全生命周期能耗、一次能源消耗以及主要污染物的排放等方面受车辆寿命的影响较小,在长期运行过程中更能发挥其在节能减排方面的优势.     

步进应力加速寿命试验数据处理方法在产品定寿试验中的应用

目的理顺步进应力加速寿命试验数据处理方法,促进步进应力加速寿命试验的广泛应用。方法通过产品寿命分布类型估计、试验数据转换、回归模型建立,模型参数估计等步骤,评估产品在正常应力水平下的寿命指标达到情况。结果利用某产品试验数据对步进应力加速寿命试验数据处理方法进行了应用。结论建立了试验数据处理方法步骤,针对步进应力加速寿命试验的设计提出了建议。