基于Hybrid Ⅲ胸部的非致命动能冲击响应测试方法

为有效获得非致命动能冲击的响应参数,解决获取冲击目标样本困难以及可能引发的法律与伦理等问题,提出一种基于假人的测试方法。该方法使用Hybrid Ⅲ第50百分位国际标准假人进行测试,分别用两种不同的非致命动能武器及弹药在6种距离对其胸部进行射击,通过Hybrid Ⅲ假人内置传感器记录冲击过程中假人胸部的冲击响应,并对试验结果进行分析、讨论。试验表明,该方法能有效获得用于评价假人胸部力学响应的加速度、位移、动能等数据,使得对人体受动能冲击的损伤情况进行定量描述成为可能,能应用于大多数非致命动能武器。

一种MJ级动能冲击下导向钢架的保护装置

针对导向钢架在MJ级动能冲击作用下的保护问题,依据大型跌落塔导向钢架的承受载荷状态,在泡沫铝铜合金与薄壁圆柱壳的吸能特性研究基础上,提出并实现了一种具有梯度缓冲吸能特性的保护装置。该装置的有效性已得到试验验证,并在实际工程中得到应用。

基于缺震理论的冲击危险性预测方法研究

由于煤矿冲击地压发生时间、地点、区域的随机性、复杂多样性和突发性,使得冲击地压的预测工作变得极为困难复杂。目前普遍采用的采矿方法和采矿地球物理方法预测存在漏报的问题,其可靠性较低。为提高冲击地压预测的准确度,研究了一种基于工作面顶板能量释放的冲击危险性预测方法,通过比对顶板能量理论释放值与实际周期内顶板能量释放值,预测工作面下一周期内发生强矿震的概率,实现预警参数的动态调整,提高了工作面阶段性冲击危险预测的可靠性。

单层球面网壳冲击响应规律及抗冲击性能研究

对单层球面网壳结构进行了网壳结构冲击试验,并采用ANSYS/LS-DYNA对网壳结构受冲击荷载作用进行了参数分析。根据网壳受冲击后的变形及破坏形态,定义了4种冲击响应模式。针对不同冲击响应模式间的转换规律,提出利用临界冲击动能作为网壳结构的抗冲击性能的评价指标,并分析了不同钢材强度对结构抗冲击性能的影响。结果表明,单层网壳结构的冲击响应模式随冲击物动能呈规律性变化,利用临界冲击动能可以方便的对网壳结构抗冲击性能进行评价,使用高强度材料可有效提高单层网壳结构的抗冲击性能。

金属板料高频冲击成形技术研究

首次提出利用高频冲击实现板料成形的新技术——高频冲击成形,根据能量理论,建立板料的变形量与冲击动能、材料性能等参数之间的关系,为分析各种参数对成形过程的影响提供了理论依据。利用高频气缸驱动冲击件对薄板进行冲击试验,试验的初步结果表明,高频冲击成形是一种新的塑性成形技术,具有低成本、高效率和高柔性的特点。能适用于一般模具无法成形的结构,拓展了冷冲压成形的零件范围。

冲击荷载下单层网壳结构的整体倒塌分析

对60m跨度的K6型单层球面网壳建模,利用ANSYS/LS-DYNA对其在不同质量及速度冲击物作用下的动力响应进行大量参数化分析。提取了关键节点的位移时程曲线,针对损伤最严重的整体倒塌模式进行了研究。得出了网壳结构在冲击荷载作用下出现整体倒塌现象与冲击物动能及节点位移的关系以及冲击过程动能传递率的分布规律。研究结果表明,冲击物质量越大,使K6网壳发生倒塌所需动能越少;当冲击物作用使关键节点的竖向位移值大于临界位移值时,网壳结构会发生倒塌现象;当冲击物携带动能为临界倒塌冲击动能时,冲击过程的动能传递率最大。

磨料质量分数对预混合磨料水射流破岩效果的影响

预混合磨料水射流是突破煤矿深长钻孔内高效破煤岩技术瓶颈的有效技术,在坚硬顶板治理、沿空留巷和硬煤增透具有广泛应用前景。磨料质量分数是影响其破煤岩效果的重要因素。为明确磨料质量分数对磨料加速、分布以及冲击动能的影响,基于离散元的耦合模型(CFD-DEM模型),考虑颗粒间的摩擦、碰撞,添加颗粒相体积分数和动量源相,修正VOF多相流模型,开发用户自定义函数(UDF)通信接口,精确计算了磨料质量分数对磨料颗粒加速运动与分布的影响,准确描述了磨料粒子对水射流流场的影响。结合预混合磨料水射流破岩实验,得到了以下结论:在固定压力下,不同磨料质量分数的射流液固能量转化效率不同,导致磨料冲击动能不同。提高磨料质量分数,能够提高破煤岩效果,但存在最优值。每一压力条件下都有与之相适配的最优质量分数,此质量分数下能量转化效率最高,磨料冲击动能最大。如射流压力5 MPa时,80目(0.178 mm)石榴石最优质量分数为11%。同一质量分数下,提高射流压力可提高磨料冲击动能,但是能量转化率和利用率降低。提高压力使射流速度增加,曳力增大,但射流与磨料接触时间缩短,导致射流能量未能及时转化为磨料动能。相较于提高射流压力,适当增加磨料质量分数以提高能量转化效率和能量利用率,是达到最佳破煤岩效果的更经济低能耗的方式。

高强混凝土回弹仪检测混凝土抗压强度的试验研究

运用中型回弹仪和高强混凝土回弹仪两种仪器同时对强度为C50-C80的混凝土试块进行回弹检测，通过对两组回弹数据及抗压强度值的回归拟合，分别建立其各自的回弹测强曲线，并分析两种回弹曲线的计算误差从而比较两种回弹仪的检测精度。结果表明，高强混凝土回弹仪比中型回弹仪更适合于检测高强混凝土强度的检测。

单层网壳结构冲击响应模式及临界冲击动能研究

采用ANSYS/LS-DYNA对60m跨度的K-6型单层球面网壳建立有限元模型,通过大量参数分析得出K-6网壳的4种冲击响应模式及其变化规律,考虑材料屈服强度、弹性模量及杆件截面积对网壳冲击响应模式及其分布规律的影响,提取网壳在冲击作用下发生局部倒塌和整体倒塌时的临界冲击动能,比较材料特性及截面特性对网壳抗冲击性能的影响,拟合了临界冲击动能的计算公式,并与有限元结果进行了对比。结果表明,K6网壳的冲击响应模式随冲击物携带动能的改变呈规律性变化。在杆件的截面特性和材料特性中,杆件的截面积对网壳的抗冲击性能影响较大,提高杆件的截面积可以大幅度提高网壳抵抗冲击荷载的能力。网壳的临界冲击动能可以利用公式进行计算。该结果对于网壳结构的抗冲击设计具有实际意义。

针阀式缓冲气缸和溢流式缓冲气缸缓冲方式的比较

缓冲气缸是气压传动系统中最常用的一种执行元件。本文介绍了针阀式缓冲气缸和溢流式缓冲气缸的结构及工作原理。通过仿真计算比较了它们的缓冲特性和吸收冲击的能力。结果表明:溢流式缓冲比针阀式缓冲吸收冲击能力强,速度平稳,适合于气缸高速运行的场合。所得结果对设计和使用缓冲气缸具有一定的实际意义。

新型金刚石链锯运转可行性研究(二)——链条最大容许运动速度的计算

文章结合新型金刚石链锯运转特点,对其最大容许运行速度进行计算评估。通过链锯链条与链轮的啮合冲击运动进行计算,求得链条极限冲击速度。并通过单位冲击动能进一步进行推导计算出新型金刚石链锯最大线运行速度。

Improving impact wear resistance of Ti-6Al-4V alloy treated by laser shock peening

The effects of laser shock peening (LSP) on the impact wear behavior of Ti-6Al-4V alloys were investigated by a homemade impact wear test rig. The microstructure and mechanical properties of the peened samples were studied. During the impact wear test, the energy absorption, impact force, wear contact time and wear mechanism of all the test samples were investigated in terms of the influence of the impact kinetic energy. The results showed that microhardness, elastic modulus and residual compressive stress of the treated samples were markedly improved. The wear resistances of both treated samples were highly improved after LSP, and a higher pulse energy corresponded to a more obvious effect. Besides, the wear in all test samples involved a combination of abrasive and oxidation wear and fatigue spalling.

Simulation and experimental study of 7A09 aluminum alloy milling under double liquid quenching

To explore the influence of double liquid quenching on the cutting performance of the 7A09 aluminum alloy,quasi-static compression and dynamic impact tests were carried out on the 7A09 aluminum alloy after double liquid quenching using an MTS810.23 universal testing machine and split-Hopkinson pressure bar(SHPB).The experimental data were fitted to obtain the Johnson–Cook constitutive model parameters of the alloy.Simulations of the machining process were carried out using the Deform-3D finite element software.The results showed that the rheological stress increased with the increase in strain rate and the decrease in temperature.The increase in the cutting speed and feed caused the cutting temperature to rise sharply,whereas the influence of the cutting amount on the cutting temperature was weak.Because of the presence of chip nodules,there was extremum in the cutting force vs cutting speed curves.The increase in the feed and cutting depth increased the cutting area Ac,so the cutting force also increased.The simulation results were verified by experiments.The simulation predictions were in good agreement with the test values,and the cutting force and temperature variations with the cutting parameters were the same.Thus,the correctness of the 7A09 aluminum alloy finite element model was verified.

Effect of T6I6 treatment on dynamic mechanical behaviour of Al-Si-Mg-Cu cast alloy and impact resistance of its cast motor shell

The effect of T6I6 treatment on the dynamic mechanical and microstructure behaviour of Al-Si-Mg-Cu cast alloy was investigated using split Hopkinson pressure bar(SHPB), transmission electron microscopy(TEM), and highresolution transmission electron microscopy(HRTEM). Besides, the impact resistances of T6I6 and T6 motor shells of new energy vehicles made of Al-Si-Mg-Cu cast alloy were compared using a trolley crash test. The results indicated that the main strengthening-phases of the T6 peak-aged and T6I6 peak-aged alloy were GP zone and β″ precipitates. T6I6treatment can increase the density and size of β″ precipitates in peak-aged alloy and enhance both its tensile strength(σb)and elongation(δ). The dynamic toughness values of T6I6 samples are 50.34 MJ/m^(3) at 2000 s^(-1) and 177.34 MJ/m^(3) at 5000 s^(-1) which are 20% and 12% higher than those of T6 samples, respectively. Compared with a T6 shell, the overall deformation of T6I6 shell is more uniform during the crash test. At an impact momentum of 3.5×10;kg·m/s, the T6I6shell breaks down at 0.38 s which is 0.10 s later than the T6 shell.

水射流切割炸药的实验

水射流切割炸药是否安全，关键是切割时炸药是否爆炸。炸药的敏感度越高，水射流的冲击动能越强，切割时炸药起爆的可能性越大。因此，要在切割炸药起爆可能性最大条件下进行安全性试验。对常用JB-9014，RHT-901，JOB-9003，JO-9159共144发炸药进行切割试验，在水压140～350MPa，相对移动速度20～40mm／min，靶距4mm的条件下切割，无一发发生爆炸或爆燃。

THE MEASUREMENT AND STUDY OF BLASTING VIBRATION AFFECTING IN SITU CAST CONCRETE LINING OF VERTICAL SHAFT

Vertical shaft is main form of drivage in deep mineral depoist. They also serve as the entrance into and the exit from the underground mine. The main problems in shaft and tunnel engineering is to solve the contradiction between drivage and lining. The measurement of blasting vibration affecting concrete lining strength of vertical shaft is carried out in experiment and theory in this paper.

Microstructure, morphology, crystallization and rheological behavior of impact polypropylene copolymer

Impact polypropylene copolymer (IPC), named polypropylene catalloy, not only possesses excellent impact property, but also presents good rigidity. Its superior performances result from the complicated composition and microstructure. In the present article, recent progress in the studies on microstructure, morphology, crystallization and rheological behavior of IPC is summarized, and findings of the authors and their collaborators are reported. In general, IPC is divided into three components, i.e., ethylene-propylene random copolymer (EPR), a series of different segment lengths ethylene-propylene copolymer (EbP) and propylene homopolymer. The reasonable macromolecular structures of EbP and a multilayered core-shell model of dispersed phase structure in IPC were proposed, in which the dispersed phase consists of an outer EbP shell, an inner EPR layer and an EbP core. It is found that the annealing at melt-state may lead to an abnormal phase inversion, and the phase inversion disappears when temperature cools down to room temperature. The cause of phase inversion is ascribed to the existence of EbP component, which results in the stronger activity of the dispersed phase. The crystalline structure and morphologic results confirm the formation of β-iPP in IPC. Furthermore, it is found that the ethylene content in IPC and cooling rate of the samples have an important influence on the formation of β-iPP. Based on the crystallization kinetics analyzed by Lauritzen-Hoffman theory, crystallization behavior of different IPC samples is discussed and it is proposed that the dilution effect of ethylene propylene copolymer has a more remarkable influence on surface nucleation than on crystal growth. In addition, annealing at high temperature can result in the changes of chain structure for IPC, and this instability is ascribed to the oxidative degradation and crosslink reaction mainly in iPP component.

Pneumatic Performance of Staggered Impulse Turbine for OWC Wave Energy Convertor

A staggered impulse turbine is proposed for asymmetric air flows in Oscillating Water Column wave energy plants, which is expected to enhance the pneumatic power output in a wave cycle. The setting angle of rotor blades is set as 5°. The 3D numerical simulations were conducted under steady conditions using MRF and Mixing Plane model based on CFD software Fluent 12.0. Its mean efficiencies under different velocity amplitude ratios are studied using quasi-steady analysis, which derive corresponding data from the numerical simulation. It is found that the staggered turbine shows better performance than the conventional one under the asymmetrical air flows. Furthermore, its mean efficiency and output-work in a wave period are compared with another unsymmetrical twin impulse turbine system. The results show that the staggered turbine shows better output-work performance than the twin turbine system over the high flow coefficient domain(φ>0.7), which provides more choices to future research on turbine's optimization.