用于Ti35合金腐蚀试验的蒸发模拟料液组成研究

本文通过对高放蒸发料液组成及蒸发操作工况进行分析,筛选出蒸发料液中所含的主要元素,从电化学腐蚀的角度确定需要被模拟的元素,根据相同(或相近)氧化还原电位离子模拟的原则,用非放射性元素代替放射性元素,用氧化还原电位相近的离子代替高放废液中强氧化性离子,确定蒸发模拟料液的组成,为研究Ti35合金在后处理高放废液蒸发操作条件下耐腐蚀性能提供支持。

高固含量改性双基推进剂模拟料连续剪切压延工艺与性能研究

为掌握高固含量改性双基推进剂连续剪切压延工艺特点,采用固体填料质量分数为30%~50%的高固模拟料进行连续剪切压延试验,研究了模拟料的粘辊状态、温度分布、含水率等;并通过SEM分析了试样的微观状态和混合效果,结合DSC定量分析了物料的塑化度。结果表明,随固含量增加,物料在剪切压延机的进料端粘辊效果变差,中后部粘辊良好,辊面温度降低,含水率降低;相同固含量下,Al粉的引入会增加辊面物料的温度,使压延样品含水率略有降低;固含量越高,模拟料的黏度越大,且含Al样品黏度大于不含Al样品;SEM测试及煅烧实验表明物料分布均匀且混合良好;体系的塑化度随固含量增加而降低,受固体组成影响较小。对于高固含量特别是含Al粉推进剂,建议适当降低压延温度。

液液萃取–离子色谱法测定乏燃料后处理模拟料液中的叠氮酸

建立乏燃料后处理模拟料液中叠氮酸的液液萃取–离子色谱测定方法。在相比1∶1的情况下,以30%TBP–煤油对1 g/L的叠氮酸进行萃取,将目标料液稀释10倍以上体积即硝酸浓度在0.3 mol/L以下,以提高叠氮酸根萃取率,同时降低硝酸、铀及其它金属离子的干扰;用浓度不低于2mmol/L的KOH溶液对叠氮酸根进行反萃取;用Dionex-AS11HC大容量阴离子色谱柱进行分离。叠氮酸的质量浓度在0.04～12μg/mL范围内与色谱峰面积呈良好的线性关系,线性相关系数(r^2)为0.999 4,对原始料液的检出限为0.27μg/mL。测定结果的相对标准偏差为2.17%(n=10),加标回收率为89.5%～109.0%。该方法灵敏度高,重复性好,抗杂质离子干扰,可用于乏燃料后处理料液中叠氮酸的测定。

沉降式离心机模拟料工艺性能验证试验

本试验首先对沉降式离心机进行空载、水负载验证试验,在运行达到稳定的基础上选用氧化铝(刚玉粉磨料)作为料液的不溶悬浮固体,以硝酸锶调节液相比重和粘度构成Al2O3-Sr(NO3)2水模拟体系,进行沉降式离心机的模拟料液负载工艺性能验证试验,从而基本确定了本沉降式离心机的运行工况。

乏燃料后处理模拟工艺料液中锆的分析

研究给出了分光光度法和X射线荧光法分析乏燃料后处理模拟工艺料液中锆的适用条件和分析步骤。对经TBP萃取过或从TBP中反萃制备的样品 ,用二甲酚橙或偶氮砷Ⅲ做显色剂的分光光度法分析是不可行的 ,建议采用X射线荧光法分析样品中的锆。

莺歌海盆地晚第三纪构造特征的三维泥料模拟实验及其动力学意义

莺歌海盆地是发育在古红河断裂带之上的新生代盆地,晚第三纪的构造运动触发了盆地中热流体自超压封存箱向外大规模突破,使热流体及泥质的活动具有规律性成群成带的特征。本次实验基于相似理论,在对盆地的演化史及区域构造应力场充分分析的基础上,进行了晚第三纪盆地构造应力场的三维泥料模拟,证实了红河断裂右旋走滑派生的拉分效应控制了莺歌海盆地晚第三纪的构造活动,而晚第三纪的构造活动又是雁列式断裂展布及底辟体分布的主导因素。

模拟炸药浆料搅拌过程的电容层析成像探索

探讨了模拟炸药浆料(液/固两相流)的滚动式搅拌过程及其物流状态电容层析成像的试验,试验结果显示该装置可以实时测量和反映管道内液固两相流动的情况,表明电容层析成像是一个具备炸药浆料这种液/固两相流搅拌过程中观测容器内流体成分分布、流速等重要信息能力的一种新的监测工具,将为观测炸药浆料搅拌过程内部行为提供了一种可视化技术,但图象分辨率有待进一步提高.

机头内熔料流动模拟及微机控制吹膜技术

用计算机建立了吹塑薄膜机头仿真模型,以展示机头的内部结构,模拟了塑料熔料在机头内部的流动状态,并介绍了吹膜过程中微机控制技术应用的现状。

室内模拟陈垃圾的力学特性

研究陈垃圾的力学特性对垃圾填埋场开发再利用具有重要的指导意义。在室内生物降解试验的基础上,分析了陈垃圾物理组成特性,提出用模拟料来研究陈垃圾的力学特性。通过静三轴试验,研究了不同降解程度陈垃圾的力学性质,采用变形模量、黏聚力及内摩擦角作为评价模拟料对陈垃圾模拟准确性指标。结果表明,随着降解程度的增加,可降解有机物质量的减少,垃圾中塑料等难降解有机物和主要无机物成分的相对含量稍有增加,可降解有机物质量损失与降解程度之间的关系可用双曲线来描述。降解程度0和39.5%的陈垃圾及模拟料的应力-应变关系曲线,均符合应变硬化规律。模拟料可以较好地模拟陈垃圾的力学特性。

3D modeling for effect of tool eccentricity on coupled thermal and material flow characteristics during friction stir welding

A novel three-dimensional numerical model is proposed to investigate the effect of tool eccentricity on the coupled thermal and material flow characteristics in friction stir welding(FSW) process.An asymmetrical boundary condition at the tool-workpiece interface,and the dynamic mesh technique are both employed for the consideration of the tool eccentricity during tool rotating.It is found that tool eccentricity induces the periodical variation of the heat densities both at the tool-workpiece interface and inside the shear layer,but the fluctuation amplitudes of the heat density variations are limited.However,it is demonstrated that tool eccentricity results in significant variation of the material flow behavior in one tool rotating period.Moreover,the material velocity variation at the retreating side is particularly important for the formation of the periodic characteristics in FSW.The modeling result is found to be in good agreement with the experimental one.

FINITE ELEMENT MODELING OF MODERATELY THICK COMPOSITE PLATE WITH PIEZOELECTRIC SENSORS AND ACTUATORS

A rectangular finite element for laminated plate with bonded and/or embedded piezoelectric sensors and actuators is developed based on the variational principle and the first order shear deformation theory. The element has four-node, 20-degrees-of-freedom with one potential degree of freedom for each piezoelectric layer to represent the piezoelectric behavior. The higher order derivation of deflection is obtained by using the normal rotation expressions to take the effects of transverse shear deformation into considerations. The finite element can accurately simulate the deformation of both thin and moderately thick plates. A Fortran program is written and a number of benchmark tests are exercised to verify its effectiveness. Results are compared well with the existing data. The unbalanced composite with piezoelectric layers is then analyzed by using the model. Results show that the changes of the ratio between the thickness of positive angle layers and the negative angle layers have an effect on the deformation of the structure under the same electric loading.

Development,modeling and application of piezoelectric fiber composites

Piezoelectric materials are capable of actuation and sensing and have been used in a wide variety of smart devices and structures.Active fiber composite and macro fiber composite are newly developed types of piezoelectric composites,and show superior properties to monolithic piezoelectric wafer due to their distinctive structures.Numerous work has focused on the performance prediction of the composites by evaluation of structural parameters and properties of the constituent materials with analytical and numerical methods.Various applications have been explored for the piezoelectric fiber composites,including vibration and noise control,health monitoring,morphing of structures and energy harvesting,in which the composites play key role and demonstrate the necessity for further development.

Identification of processing window for extrusion of large thick-walled Inconel 625 alloy pipes using response surface methodology

Identifying suitable processing window is necessary but difficult for achieving favorable microstructure and performance in extrusion of large thick-walled pipe with difficult-to-deform Inconel 625 alloy. In this work, a method was established for identifying the extrusion process window considering temperature control using response surface methodology. Firstly, the response surface models, which correlate temperature rise and peak temperature to key extrusion parameters, have been developed by orthogonal regression based on finite element calculated data. Secondly, the coupled effects of the key extrusion parameters on the temperature rise and peak temperature have been disclosed based on the regression models. Lastly, suitable extrusion processing windows, which are described by contour map of peak temperature in the space of extrusion speed and initial billet temperature, have been established for different extrusion ratios. Using the identified process window, a suitable combination of the key extrusion parameters can be determined conveniently and quickly.

Forced convection rheoforming process for preparation of 7075 aluminum alloy semisolid slurry and its numerical simulation

A self-developed forced convection rheoforming （FCR） machine for the preparation of light alloy semisolid slurry was introduced. The microstructure characteristics of 7075 aluminium alloy semisolid slurry at different stirring speeds prepared by the FCR process were analyzed. The experimental results suggest that with the increase of the stirring speed, the mean grain size of the semisolid decreases and the shape factor as well as the number of primary grains increase. Meanwhile, the preparation process of semisolid slurry was numerically simulated. The flow characteristics of the melt in the device and the effect of the stirring speed on temperature field and solid fraction of the melt were investigated. The simulated results show that during the preparation process of semisolid slurry, there is a complex convection within the FCR device that obviously changes the temperature field distribution and solid fraction of the melt. When the convection intensity increases, the scope of the undercooling gradient of the melt is reduced and temperature distribution is improved.

Visualization and simulation of plastic material flow in friction stir welding of 2024 aluminium alloy plates

Thin copper sheets as marker material were embedded into weld path of 2024 aluminium alloy plates and their final position after friction stir welding was examined by metallographic techniques. Referring to the visualized material flow patterns, a three-dimensional model was developed to conduct the numerical simulation of the temperature profile and plastic material flow in friction stir welding. The calculated velocity contour of plastic flow in close proximity of the tool is generally consistent with the visualized results. As the tool rotation speed increases at a constant tool travel speed, the material flow near the pin gets stronger. The predicted shape and size of the weld nugget zone match with the experimentally measured ones.

Effect of Nitrogen, Phosphorus and Potassium on the Content and Yield of DNJ of Mulberry Leaves in Spring

[Objective] This study aimed to scientifically improve the 1-deoxynojimycin （DNJ） yield of mulberry leaves in spring. [Method] ＂3414＂ experimental design was adopted to investigate the effects of different fertilizer application rates of nitrogen, phosphorus and potassium on the DNJ content in mulberry leaves. The regression relationship was further simulated with DNJ yield as the objective function and fertil- izer application rates of nitrogen, phosphorus and potassium as the regulatory factors. [Result] The results showed that nitrogen, phosphorus and potassium all have great effects on the DNJ content in mulberry leaves at different parts of mulberry tree （Morus alba）; the DNJ content in mulberry leaves increases with the increasing single-factor fertilizer application rate and reaches the maximum under N2P2K2 level; different fertilizer application rates and combinations of nitrogen, phosphorus and potassium can significantly affect the DNJ content in mulberry leaves; according to the simulated fertilizer effect function, the optimal economic yield of total DNJ in mul- berry leaves was 23.23 kg/hm^2, the recommended fertilization indicators were 286.11 kg/hm^2 N, 95.22 kg/hm^2 P2O5 and 159.62 kg/hm^2 K20. [Conclusion] After confirmation in productive practice, this optimal fertilization program can provide reference for the construction of mulberry plantation with high yield and high quality of DNJ.

Material driven workability simulation by FEM including 3D processing maps for magnesium alloy

The three-dimensional （3D） processing maps considering strain based on the two-dimensional （2D） processing maps proposed by PRASAD can describe the distribution of the efficiency of power dissipation and flow instability regions at various temperatures, strain rates and strains, which exhibit intrinsic workability related to material itself. Finite element （FE） simulation can obtain the distribution of strain, strain rate, temperature and die filling status, which indicates state-of-stress （SOS） workability decided by die shape and different processing conditions. On the basis of this, a new material driven analysis method for hot deformation was put forward by the combination of FE simulation with 3D processing maps, which can demonstrate material workability of the entire hot deformation process including SOS workability and intrinsic workability. The hot forging process for hard-to-work metal magnesium alloy was studied, and the 3D thermomechanical FE simulation including 3D processing maps of complex hot forging spur bevel gear was first conducted. The hot forging experiments were carried out. The results show that the new method is reasonable and suitable to determine the aoorooriate nrocess narameters.

Numerical study of pressure drop for a new fibrous media model

An open-source computational fluid dynamics（CFD）code named OpenFOAM is used to validate the flow field characteristics（flow patterns and pressure drop）around a single cylinder.Results show that OpenFOAM is suitable for simulating the low Reynolds number flow and Shaw＇s analytical expression is one of the solutions to Stokes＇ paradox.Experiments are performed on fibrous media and OpenFOAM simulation is carried out using the Tronville-Rivers two-dimensional random fiber model in terms of the characteristics of pressure drop.It is shown that the Kuwabara model predicts the pressure drop of fibrous filter media more accurately than the Happel model,and the experimental pressure drop is between simulated pressure drops with both non-slip and full-slip boundaries on fiber surfaces.

Finite element analysis of pressure on 2024 aluminum alloy created during restricting expansion-deformation heat-treatment

Metals heat-treated under high pressure can exhibit different properties. The heat-induced pressure on 2024 aluminum alloy during restricting expansion-deformation heat-treatment was calculated by using the ABAQUS finite element software, and the effects of the mould material properties, such as coefficient of thermal expansion （CTE）, elastic modulus and yield strength, on the pressure were discussed. The simulated results show that the relatively uniform heat-induced pressure, approximately 503 MPa at 500 ℃, appears on 2024 alloy when 42CrMo steel is as the mould material. The heat-induced pressure increases with decreasing the CTE and the increases of elastic modulus and yield strength of the mould material. The influences of the CTE and elastic modulus on the heat-induced pressure are more notable.

Single gate optimization for plastic injection mold

This paper deals with a methodology for single gate location optimization for plastic injection mold. The objective of the gate optimization is to minimize the warpage of injection molded parts, because warpage is a crucial quality issue for most injection molded parts while it is influenced greatly by the gate location. Feature warpage is defined as the ratio of maximum displacement on the feature surface to the projected length of the feature surface to describe part warpage. The optimization is combined with the numerical simulation technology to find the optimal gate location, in which the simulated annealing algorithm is used to search for the optimum. Finally, an example is discussed in the paper and it can be concluded that the proposed method is effective.