齿轮箱点蚀的在线故障诊断系统

基于傅里叶变换的谱分析具有一定的局限性,是一种全局变换,而小波具有很好的时频分辨能力,将Hilbert变换和小波分析方法结合起来对齿轮箱点蚀故障进行了研究。以JZQ250型齿轮点蚀故障为分析对象,对测得的振动加速度信号进行小波变换和Hilbert变换。为了更好地进行人机交互,利用VC++的强大界面开发能力把其嵌入,实现对数据的分析,并设计一个规则库。结果表明:所设计的界面可行并可有效诊断故障。     

基于希尔伯特变换的风电机组齿轮箱故障诊断方法研究

齿轮箱作为风电机组关键部件,由于运行环境以及工况的复杂性,易出现故障,严重威胁机组安全稳定运行。因此,对齿轮箱进行故障诊断对确保风电机组稳定运行具有重要意义。在介绍齿轮箱结构特点、故障模式、振动监测的基础上,结合齿轮箱结构特点,给出齿轮与轴承故障特征频率的计算方法。同时采用希尔伯特变换与倒谱分析相结合的方法对齿轮箱振动数据进行分析,提取故障特征频率。经实例验证,该方法能够准确得到齿轮箱故障频率的同时定位齿轮箱故障,实现风电机组齿轮箱的故障诊断。     

基于传动误差法的装载机减速机构故障诊断

针对核电装载机减速机构因齿轮轮齿磨损而影响其定位精度的问题,建立了一种包含故障信息的齿轮系统传动误差信号模型;基于传动误差法对减速机构进行故障诊断,便于企业早日发现故障,及时更换故障元件,减少经济损失。运用ADAMS软件仿真包含磨损故障的误差信号。改进了传统计算阶次跟踪重采样方法,对原始时域信号进行角域COT(Computed Order Tracking)处理;对重采样后的信号进行EEMD分解(Ensemble Empirical Mode Decomposition),将故障分量进行阶次分析,找出故障特征频率;进一步,对故障分量进行倒谱分析,准确识别出故障元件。分析结果表明,改进算法使重采样效率提高了2/3;阶次分析与倒谱分析相结合的方法能够有效识别出装载机减速机构的故障元件。     

基于Hilbert-Huang 变换的齿轮故障诊断研究

提出一种基于Hilbert-Huang变换的齿轮磨损故障诊断的新方法。介绍Hilbert-Huang变换的基本原理,并将Hil-bert-Huang变换应用于齿轮箱中齿轮磨损故障诊断,通过选取表征齿轮磨损故障的固有模式函数进行边际谱和能量谱分析,可提取齿轮故障振动信号的特征。齿轮故障实验结果表明,应用这种分析方法,能够有效地诊断齿轮的磨损故障。     

基于扭振信号的行星齿轮箱故障诊断

行星齿轮箱具有传动比大、传动效率高等优点,但比定轴齿轮有更复杂的结构,因常工作在恶劣的条件下,容易出现磨损或疲劳裂纹等故障。为有效诊断行星齿轮传动故障,本文采用基于扭振信号的故障诊断方法,并利用增量式编码器采集扭振信号。通过与横向振动信号相比,发现扭振信号频谱结构简单、对故障特征更加敏感。通过对行星轮故障实验扭振信号的分析,故障下的故障特征频率幅值有2倍的提升。角速度形式的扭振信号能准确诊断故障,为行星齿轮箱故障诊断提供了简明有效的途径。     

基于时间序列分析的行星齿轮箱故障诊断

齿轮箱运转的环境会导致信号采集时产生强大的噪声干扰,提出时间序列的方法对齿轮箱进行故障诊断。采用时间序列分析对行星齿轮箱进行谱分析,通过与传统频谱分析比较可以看出,该方法具有较好的识别能力。通过Labview虚拟仪器设计的数据采集系统进行数据的采集提取特征信号,确定模型阶次为5阶,最后利用AR模型参数算法来确定其正常状态下齿轮参数容差范围,在阶次不变的情况下分析出故障信号的模型参数,与正常信号参数容差范围进行对比,从而对齿轮箱故障进行诊断,该方法在齿轮诊断方面效果较为显著。     

小波包与Hilbert分析法在旋转设备故障诊断中的应用

文中分析了对齿轮和滚动轴承的故障诊断在旋转机械设备中的重要性,介绍了小波包分析和Hilbert分析的理论,针对齿轮和滚动轴承故障信号的非平稳性特点,提出了一种基于小波包分析和Hilbert分析法相结合的故障诊断方法.在matlab中应用该方法对齿轮的点蚀故障和滚动轴承的内环故障进行诊断,仿真结果表明,基于小波包分析与Hilbert分析法相结合的方法可以有效地提取齿轮和滚动轴承的故障特征频率,从而可以迅速地识别出齿轮和滚动轴承的故障类型.     

基于磨粒监测的齿轮箱磨损特性分析

磨粒监测的目的是掌握齿轮箱的运动状态,发现早期的潜在故障,并给出适当的维护行动。基于自主研制的齿轮磨损试验台,对传动齿轮进行全寿命周期试验,探究了油液粘度、污染度和铁磁性颗粒对齿轮磨损性能的影响。结果表明,齿轮油粘度下降会导致齿轮箱磨损加剧;磨粒的出现又进一步加剧齿轮油的老化,造成齿轮箱污染度升高。当齿轮箱进入剧烈磨损期时,产生的磨粒尺寸偏大,此时预示着齿轮箱已经开始失效。齿轮箱的主要失效机制为磨粒磨损和疲劳磨损,且伴有一定的粘着磨损。     

倒频谱法在齿轮箱故障诊断中的应用

基于LABVIEW的虚拟仪器平台建立数据采集系统,实现了对齿轮进行全生命周期实验过程中采集到大量振动信号数据,提出使用时域分析法（时域同步平均）与频域分析法（功率谱）相结合的信号处理方法对振动信号数据按齿轮可能出现的各种运行状态加以分类,从而有重点的应用倒频谱法对已经出现故障的齿轮箱振动信号进行分析,倒频谱的边频带频谱识别能力有助于研究啮合频率及边频特征,进而准确诊断出齿轮故障性质,并定位出故障齿轮。实验结果得到的齿轮各阶段运行状态数据在工程中很实用,具体涉及齿轮状态判断、故障阈值设定、故障识别及定位等用途。     

基于深度自编码网络与模糊推理相结合的矿用齿轮箱故障诊断方法

提出一种基于深度自编码网络与模糊推理相结合的矿用齿轮箱故障诊断方法。通过对完整齿轮、裂齿齿轮和缺齿齿轮3种齿轮工作状态的声信号进行小波分析并建立特征数据库,构建深度自编码网络与模糊推理系统相结合的诊断系统,实现了齿轮故障诊断与辨识。实验结果表明:这种基于声信号的故障诊断方法能够有效检测矿用齿轮箱的运行状况;与传统神经网络诊断方法以及奇异值分解诊断方法相比,该诊断方法对故障状态的辨识准确度分别提高了3.8%和8%。与传统基于振动信号的故障诊断方法相比,基于声信号的诊断方法对故障状态的辨识准确度无明显差别。表明深度自编码网络模糊推理系统同样适用于基于振动信号的矿用齿轮箱的故障特征提取与分析。     

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).     

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.     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.