Study on pressure capacity of multilayer stagger-split die,using simulation-based optimization

A novel device with a large cavity is investigated with regard to pressure capacity. This device is the multilayer stagger-split die (MSSD) that employs one or more supported rings and the multilayered divided body assemblage. The divided bodies are arranged in a staggered manner between adjacent layers. The pressure capacity of this device is calculated based on different failure criteria and using the simulation-based optimization approach. The results are compared with those of the belt-type die (BTD). A comparative experiment is also carried out to verify the simulated results. We conclude that the conditionality of pressure capacity of MSSD is related to die size. And MSSD can bear higher pressure than the BTD.     

Finite element analysis and experiment on high pressure apparatus with split cylinder

Ultra-high pressure belt-type die was designed with a large sample volume prism cavity and a split cylinder which was divided into eight segments to eliminate circumferential stress. The cylinder of this type die has no cambered surface on inner wall, and the inner hole is a hexagonal prism-type cavity. The divided bodies squeeze with each other, providing the massive support and lateral support effect of the cylinder. Simulation results indicate that the split cylinder with the prism cavity possesses much smaller stress and more uniform stress distribution. The split cylinder with the prism cavity has been shown to bear larger compressive stresses in radial, circumferential and axial directions due to its structure, and tungsten carbide is most effective in pure compression so this type cylinder could bear higher pressure. Experimental results prove that the high pressure apparatus with a prism-type cavity could bear higher pressure. The apparatus with a prism cavity could bear 52.2% more pressure than the belt-type die.     

六面顶压机立方压腔内压强的定量测量及受力分析

将六面顶压机立方压腔内置入电路,采用原位电阻测量确定Bi,Tl,Ba相变的方法,标定了压腔内不同位置的压力(强).通过标定立方压腔顶锤表面的压力并结合计算,分别得到了外部加载与压腔密封边受力以及合成腔体受力的对应关系.实验分析结果表明,随着外部加载的增加,当腔体压力达到5 GPa时,消耗在压腔密封边上的加载急剧上升,消耗在合成腔体的加载趋于不变,从而导致立方压腔压力达到上限.利用实验结果,分析了立方压腔在高压下的受力状态,解释了立方压腔的压力难以超过7 GPa的原因.结合立方压腔的几何结构,通过理论分析,提出了采用高体弹模量的物质作为传压介质,同时采用低体弹模量的物质作为密封边提高立方压腔压力上限的可行方案.通过定量标定叶腊石压腔轴向的压力梯度,给出了压腔内沿对称轴不同位置压力值的计算方法,此方法可为高压实验提供更精确的压力数据.     

A hybrid pressure cell of pyrophyllite and magnesium oxide to extend the pressure range for large volume cubic presses

A hybrid pressure cell of pyrophyllite and magnesium oxide (HPCPM) used in large volume cubic presses is presented. In the HPCPM, a cubic frame which is made of pyrophyllite with face-centered square holes works as gaskets, and a heteromorphosis magnesium oxide works as the pressure-transmitting medium. Our experimental results indicated that the pressure-generation efficiency using the HPCPM was improved by about 40% than that using the traditional pyrophyllite pressure cell without decreasing the anvil truncation size (without sacrificing the sample volume). The HPCPM could pressurize samples of 1000 mm³ volume up to about 8 GPa, which is significantly higher than that available using the traditional pressure cell, which reports a highest pressure of about 6 GPa.     

高温下活塞-圆筒容器内叶腊石介质的对称与不对称摩擦损耗

 本文用测定铅的熔化曲线的方法来研究高温下活塞-圆筒容器中叶蜡石介质的摩擦损耗。发现叶蜡石在高温高压条件下，其不对称摩擦明显增高，因此不能应用常温下的压力定点方法标定压力。这些不对称摩擦很可能来源于叶蜡石在高温和常温状态下具有的较为悬殊的力学性能差别，从而导致了样品组装内部高温区与外层低温区之间负的差载效应。研究认为，叶蜡石具有价廉和易加工等优点，其摩擦在高温下也可大幅度下降。如果对由于压室温度不均匀而带来的不对称摩擦作适当修正，它仍然可以作为该类容器中高温高压物性测量的较为理想的传压介质。     

蒸汽浸没射流凝结引起的冲击特性研究

本文在广泛的蒸汽压力和过冷水温度范围内,针对饱和蒸汽通过不同出口直径的喷嘴在过冷水中浸没射流凝结引起的压力冲击特性进行了实验研究,测量得到了不同轴向位置和径向位置的冲击压力,并分析了入口蒸汽压力,过冷水温度和喷嘴出口直径对冲击压力的影响规律。结果表明冲击压力主要受入口蒸汽压力和过冷水温度的影响;同时,当汽水参数以及无量纲轴向和径向距离相同时,不同出口直径的喷嘴对应的冲击压力变化很小,从而表明喷嘴出口直径对压力冲击影响很小。     

合成金刚石超高压腔内的压力剃度

 用合成金刚石通用的石墨代替过去使用的氯化银作为测定压力的传压介质材料测得了腔内的压力梯度。石墨在压力腔内压力梯度随压力的升高而增大，在中心压力为5.5 GPa时，纵向压力梯度为21.8 MPa/mm，径向压力梯度为18.8 MPa/mm；而且在较低压力下，两个方向的压力梯度相差甚微，随着压力升高，差别则较为显著。但氯化银在压力腔内的压力梯度却随压力的升高而减小。研究了测压腔内的相对压力梯度，发现相对压力梯度随压力的升高而减小。在中心压力为5.5 GPa时，纵向相对压力梯度为0.003 96 mm^-1，径向相对压力梯度为0.003 48 mm^-1。因此，应根据相对压力梯度来合理地设计合成金刚石反应腔内的温度场。     

叶蜡石高温高压相变的荧光光谱研究

 对合成金刚石过程中，叶蜡石经高温高压淬火后的不同部位进行了研究。发现叶蜡石的两条荧光线14 428 cm^-1和14 398 cm^-1在高温和高压作用下均发生蓝移，温度压力共同作用比温度压力分别作用时两峰的蓝移明显减小。通过合成金刚石的温度、压力条件的共同作用，仅在靠近合成样品位置的叶蜡石发生了相变。本文认为造成蓝移的原因是温度压力的作用使电子能级或成键电子能级发生改变。     

滑块式六含八超高压实验装置及其压力温度标定

报道了一种新型六含八超高压实验装置.三柱式的机体框架与滑块式上三下三模具同为三次对称结构,在力学上较为合理.该装置加压时具有自动校准位置能力,同步性和重复性好.模具推动八块硬质合金压砧在叶腊石八面体中产生高压.分别采用Bi丝和ZnTe晶体的压致相变点255,77,96,12 GPa,对截角边长8 mm压砧和125 mm边长叶腊石块组合的实验体系进行了室温下的压力标定,结果表明压力可达12 GPa以上.在10 GPa压力下,用WRe3-WRe25热电偶将温度标定到1560 ℃,并结合铁碳二元相图和钢 关键词： 压力标定 温度标定 六含八多压砧模具 高压装置     

钢丝缠绕剖分式超高压模具等张力预紧分析

针对超高压装置大型化受限于大质量硬质合金加工困难等问题,设计了一种新型的钢丝缠绕剖分式两面顶超高压模具。该模具主要由内部的剖分式压缸和外部的预应力钢丝组成。对采用等张力钢丝缠绕模具进行了力学模型分析,并通过有限元软件对剖分式压缸和钢丝缠绕层进行研究。结果表明:加载后压缸腔体的最大等效应力出现在压缸腔体内壁;压缸腔体尺寸稳定性与钢丝缠绕层数及钢丝直径成正比;在缠绕层内部,钢丝轴向应力与钢丝直径成反比,与缠绕层数成正比。     

Study on fracture of tungsten wire induced by acoustic cavitation at different hydrostatic pressures and driving electric powers

The near-solid wall multi-bubble cavitation is an extremely complex phenomenon, and cavitation has strong erosiveness. The melting point (about 3410 °C) of tungsten is highest among all pure metals, and its hardness is also very high (its yield strength is greater than 1 GPa). What would happen to pure tungsten wire under extreme conditions caused by collapsing cavitation bubbles at high hydrostatic pressure? In this paper, we have studied the fracture process of pure tungsten wire with diameter of 0.2 mm mounted at the focus of a standing acoustic wave produced by a spherical cavity transducer with two open ends placed in a near spherical pressure container, and also studied the macro and micro morphological characteristics of the fracture and the surface damage at different fracture stages of tungsten wire under various hydrostatic pressures and driving electric powers. The results have shown that the fracture time of tungsten wire is inversely proportional to avitation intensity with hydrostatic pressure and driving electric power, the higher the acoustic pressure caused by higher electric power, the shorter the fracture time. The possible fracture mechanisms of tungsten wire in this situation we found mainly contributed to asymmetrically bubbles collapse near the surface of tungsten wire, leading to tearing the surface apart; consequently cracks along the radial and axial directions of a tungsten wire extend simultaneously, classified as trans-granular fracture and inter-granular fracture, respectively. With the increase of cavitation intensity, the cracks tend to extend more radially and the axial crack propagation path becomes shorter, that is, mainly for trans-granular fracture; with the decrease of cavitation intensity, intergranular fracture becomes more obvious. When the hydrostatic pressure was 10 MPa and the driving electric power was 2 kW, the fibers became softener due to the fracture of the tungsten wire. The fracture caused by acoustic cavitation was different from conventional mechanical fracture, such as tensile, shear, fatigue fracture, on macro and micro morphology.     

Analytic mode matching for a circular dissipative silencer containing mean flow and a perforated pipe

An analytic mode matching scheme that includes higher order modes is developed for a straight-through circular dissipative silencer. Uniform mean flow is added to the central airway and a concentric perforated screen separates the mean flow from a bulk reacting porous material. Transmission loss predictions are compared with experimental measurements and good agreement is demonstrated for three different silencers. Furthermore, it is demonstrated that, when mean flow is present, the axial kinematic matching condition should equate to that chosen for the radial kinematic boundary condition over the interface between the airway and the material. Accordingly, if the radial matching conditions are continuity of pressure and displacement, then the axial matching conditions should also be continuity of pressure and displacement, rather than pressure and velocity as previously thought. When a perforated screen is present the radial pressure condition changes, but the radial kinematic condition should always remain equivalent to that chosen for the axial kinematic matching condition; here, results indicate that continuity of displacement should be retained when a perforated screen is present.     

Φ42 mm腔体高岭石-白云石质传压密封介质金刚石合成扩大试验

 高岭石具有良好的流动密封、固体传压及机械加工等物理性能,是传统传压密封介质原料叶蜡石的替代品。采用比纯高岭石更适合作为传压密封介质原料的某地高岭石矿物,经过配料、混料、装模、压制成型以及焙烧等工序,制成了高岭石-白云石质传压密封介质,并对其进行金刚石合成扩大试验。试验结果表明：高岭石-白云石质传压密封介质能够达到与叶蜡石质传压密封介质相当的效果;合成金刚石的单产为19 g,抗压强度不小于160 N的晶粒占32%,晶粒尺寸大于或等于0.30 mm的占82%,合成1 g金刚石的顶锤消耗小于0.5 g,合成过程稳定。     

L波段高功率线极化径向线阵列天线理论分析与数值模拟

探索了L波段的高功率线极化径向线阵列天线。基于三角形栅格形式实现了径向线圆形平面阵列天线,分析并给出了径向线并联馈电网络,并以同轴馈电的水平单圆环线极化天线为基础,利用径向线并联馈电网络设计出了间距小于一个波长下L波段高功率线极化径向线阵列天线。研究结果表明：这种结构实现径向线阵列天线的线极化辐射是可行的,该天线在中心频率1.57 GHz下,增益为19.97 dBi,轴比为-52.06 dB,反射系数为0.105 2;在1.37～1.77 GHz的频率范围内增益大于18.64 dBi,轴向轴比值小于-46.45 dB。     

L波段高功率线极化径向线阵列天线理论分析与数值模拟

 探索了L波段的高功率线极化径向线阵列天线。基于三角形栅格形式实现了径向线圆形平面阵列天线,分析并给出了径向线并联馈电网络,并以同轴馈电的水平单圆环线极化天线为基础,利用径向线并联馈电网络设计出了间距小于一个波长下L波段高功率线极化径向线阵列天线。研究结果表明：这种结构实现径向线阵列天线的线极化辐射是可行的,该天线在中心频率1.57 GHz下,增益为19.97 dBi,轴比为-52.06 dB,反射系数为0.105 2;在1.37～1.77 GHz的频率范围内增益大于18.64 dBi,轴向轴比值小于-46.45 dB。     

低温制冷机振动测试与分析

提出采用激光多普勒效应测量GM低温制冷机振动,并搭建实验台测试了RDK-408S型GM制冷机各方向的振动大小。实验结果表明,型号为RDK-408S的GM制冷机振动频率约为1 Hz,轴线方向的振动最大,约为30 m,x方向也存在脉冲振动,达到30 m,都远远大于激光约束聚变研究中所需要的振动要求,必须采取具体措施进行减振或隔振。     

低温制冷机振动测试与分析

提出采用激光多普勒效应测量GM低温制冷机振动,并搭建实验台测试了RDK-408S型GM制冷机各方向的振动大小。实验结果表明,型号为RDK-408S的GM制冷机振动频率约为1 Hz,轴线方向的振动最大,约为30 m,x方向也存在脉冲振动,达到30 m,都远远大于激光约束聚变研究中所需要的振动要求,必须采取具体措施进行减振或隔振。     

Simulation of pressure distribution in a pyrophyllite high-pressure cell by finite-element analysis

The pressure-transmitting behavior and pressure distribution of a pyrophyllite cell in a cubic-anvil large volume high-pressure apparatus is investigated by finite-element analysis (FEA). The mechanical equations describing pyrophyllite under high pressure are given, which are composed of the Drucker–Prager criterion and a linear equation of state. The related material parameters such as cohesive strength, angle of internal friction etc. are experimentally measured. The FEA simulation includes the non-uniformity deviatoric stress caused by plastic deformation and the isotropy hydrostatic pressure of the pyrophyllite cell caused by volume compression. The results demonstrate that, in such a pyrophyllite cell, almost 90{%} of the pressure is isotropy hydrostatic pressure, and the pressure gradient mainly arise from non-uniform deviatoric stresses. Simulated data are displayed using the contour and the path plots.     

光纤Bragg光栅压力传感机理研究

对光纤Bragg光栅的压力传感机理进行了理论研究。分析了引起光纤光栅中心波长偏移的各种物理效应，并对几种不同形式压力下各种物理效应所引起的灵敏度系数进行了计算。计算结果表明，纵向和横向压力灵敏度系数相反，屏蔽一个方向可获得较大的压力传感灵敏度；波导效应所引起的应变灵敏度系数都比弹光效应小几个数量级，因此可以忽略。并首次提出在不同方向的压力作用下，弹光效应对应变灵敏度具有不同的贡献。     

Effect of precompression on pressure-transmitting efficiency of pyrophyllite gaskets

Pyrophyllite is widely used both as a gasket material and as a pressure-transmitting medium, especially for a large-volume press. Its pressure-transmitting efficiency mainly depends on the following factors: geometry of anvil and pyrophyllite block, chemical composition, density and strength. For a long time, most studies have been devoted to the first two factors, whereas the third one has been studied less. In this work, we report that the pressure-transmitting efficiency of pyrophyllite is improved by precompressing. The results show that pyrophyllite was fully densified when the pressure reached about 1 GPa. The press load for Ba I–II transition in the cubic large-volume pressure cell is reduced more than 8×10⁵ N by using the densified pyrophyllite, compared with the unprecompressed pyrophyllite. Namely, the press-load utilization efficiency was improved above 15% when the precompressed pyrophyllite is used as a pressure-transmitting medium.