含缺陷管道大变形条件下安全评定系统研究

在油气管道生产管理中,地质灾害下管道的安全评定技术研究是一个重要问题。本文在系统分析地质灾害引起的管道大变形下的应力状态以及综合考虑管道表面体型缺陷等影响因素的基础上,利用ANSYS有限元分析软件的二次开发功能,以Visual C＋＋为编程工具,运用APDL语言,基于VC＋＋和ANSYS的接口技术,开发出地质灾害下管道的安全评定有限元分析系统。该系统实现了对地质灾害造成的悬空和漂移管道的参数化建模、有限元分析以及安全评定功能。     

基于仿真模拟的未焊透缺陷管道安全评价

压力管道作为调相机运行中不可缺少的部件，通常采取焊接方式进行连接，因此焊接质量直接影响调相机的安全。利用Comsol仿真模拟软件对含未焊透缺陷的压力管道及其尖端裂纹应力强度因子进行计算，并结合标准GB/T 19624—2019 《在用含缺陷压力容器安全评定》对焊接管道安全性给予相关评价。结果表明，未焊透缺陷深度临界尺寸为0.85 mm,安全评价指标临界数值为0.44;未焊透缺陷尖端裂纹强度因子大于管道材料门槛应力强度因子(1.98 MPa·mm^1/2),外载荷作用下裂纹扩展，裂纹尖端应力场强度因子K_I增大；当裂纹尖端应力场强度因子达到20钢断裂韧性(30.4 MPa·mm^1/2)时，裂纹将出现失稳扩展，造成材料的断裂。     

核级阀门电动执行器抗震试验研究

介绍了SDQH25型和SDQH50型核级阀门电动执行器的抗震试验。试验利用地震模拟试验台,采用多频波法,按照要求的响应谱用人工模拟加速度时程控制,对SDQH25型和SDQH50型核级阀门电动执行器进行动态特性探查试验和5次OBE地震模拟试验及1次SSE地震模拟试验。试验验证了SDQH25型和SDQH50型核级阀门电动执行器在地震载荷作用下能正常工作。     

基于载荷的商用车制动力分配比研究

为确定不同载荷下商用车制动力分配比的合理取值,以提高制动稳定性,提出一种基于载荷的汽车制动力分配比优化设计方法,考虑了载荷对质心位置的影响。基于ECER13法规分析了对汽车制动性能的要求,确定了汽车制动力分配系数的范围,以制动强度大小与利用附着系数差值平方和最小为约束求取了分配比最优解。将该设计方法应用于重载、中载、轻载3种工况的设计计算并进行制动仿真对比与分析。结果表明:基于载荷的汽车制动力分配比设计方法可以满足汽车在不同载荷下的制动性能要求,有效提高了汽车制动的安全性。该研究可为商用车制动力分配比控制调节提供参考。     

基于ABAQUS阀门体铸造动态温度场及热应力分析

阀门体在铸造生产过程中要求控制残余热应力,以减少在使用过程中的变形。本文利用有限元技术,选取一种典型产品为对象建立有限元模型,对铸造工况下的瞬态温度场、热应力场及综合应力场进行计算,准确显示热应力分布区域和特点,为振动时效参数的选取提供准确依据。使用数值模拟技术对铸造过程中构件的内应力分布特点和规律进行研究,提高振动时效对残余热应力的消除效果。并通过改变阀门体的测量点位置,在不同规格和温度条件下,进行了内应力的定量测定试验。     

基于有限元分析的风电联轴器结构安全性能研究

风电机组由于其工作环境的特殊性要求具有极高的安全性及可靠性，风电联轴器作为其主要的传动系统零部件在工作时主要受到转矩、转速、轴向位移及角向位移载荷的作用。本研究基于有限元仿真分析方法，得到了风电联轴器各组件在不同载荷作用下的应力值，分析了各组件的应力变化趋势及安全性能，探究了各载荷对膜片组每层膜片的应力大小和分布特征的影响规律。结果表明，该风电联轴器结构是安全的，螺栓及膜片组等效应力更易受到载荷变化的影响，为主要易损件；在不同载荷作用下膜片组等效应力最小处发生在中间层，且外层与内层膜片等效应力差异较大。     

风电机组变桨轴承软带位置及打磨量的分析与研究

对变桨轴承软带及变形计算的原理进行描述。以某大型风电机组变桨轴承为研究对象,采用有限元的方式在变桨轴承不同角度施加极限载荷和疲劳载荷,计算不同角度下变桨轴承内外圈的最大相对位移。基于该位移的大小确定轴承软带的设计位置及后续加工过程中软带位置处的打磨量,从而避免在风机运行过程中由于软带位置受载而导致的轴承损伤。     

柔性定位平台的瞬态动力学分析及疲劳寿命分析

为提高超高加速度宏微运动平台完成定位工作时的安全性和精确性，以宏微运动平台的关键部件柔性定位平台为研究对象，探究宏微运动平台在微定位工况下对柔性定位平台疲劳寿命的影响。利用SolidWorks建立柔性定位平台的三维模型，在ANSYS Workbench进行静力分析和瞬态动力学分析，获得柔性定位平台危险点的位置及疲劳分析所用载荷谱。运用Goodman曲线评估方法对平台进行疲劳评估，得出的数据均在Goodman曲线框内，评估结果合理。最后利用nCode计算柔性定位平台的疲劳损伤和疲劳寿命，得出随着驱动频率的增加，柔性定位平台的疲劳寿命在降低的结论。研究结果对超精密定位平台的研究提供了参考。     

耦合场下金属主蒸汽管道弯头纵向裂纹缺陷数值模拟研究

弯头处蒸汽速度和压力变化较大使其易发生冲蚀,使得超超临界机组弯头工况恶化。研究了纵向裂纹弯头承载与其自身几何尺寸以及裂纹尺寸的关系;剖析了裂纹弯头缺陷位置及材料随温度变化规律。使用软件绘制弯头实体模型,运用有限元软件完成实体及缺陷位置网格剖分;同时对模型施加耦合场载荷,获得了弯头在启机过程不同时间节点的应力分布。结果表明:裂纹对整个弯头应力分布影响较小,最大应力载荷部位出现在裂纹底部;在启机到运动稳定阶段弯头应力变化趋势为先增加后降低。结果能为预测管道安全提供参考。     

300MW汽轮机组T形三通的应力分析及结构优化

提出了一种降低300MW汽轮机组主蒸汽管道T形异径三通结构应力的设计方法。该方法利用三通在工作载荷下的变形数据修正原有结构，首先建立了一个有限元分析模型，并用实验结果考核了模型的有效性。在这个模型的基础上，计算了不同修正量下的结构应力。发现在修正量比较小的范围内，结构的最高应力随修正量的增大显著降低。这一结论为进一步改进三通的结构设计提供了一个新的途径。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。