海洋废弃平台桩基拆除绳锯机夹紧齿优化设计研究

海洋废弃平台桩基拆除绳锯机是一种近年发展起来的新型水下作业机具,它主要由绳锯机本体和液压控制系统构成,绳锯机夹紧瓣上的夹紧齿可以使绳锯机安全、稳定地工作。介绍了夹紧齿的结构,分析得到了夹紧齿尺寸和齿周过渡曲线的优化数学模型,采用有限元法优化得到了夹紧齿关键参数。根据优化结果设计制造了夹紧齿,实验结果表明:该夹紧齿能够满足要求,为绳锯机的安全稳定工作打下了一定的基础。     

海洋废弃平台桩基拆除绳锯机夹紧力的研究

介绍废弃平台桩基拆除水下绳锯机的组成和工作原理。对夹紧装置进行力学模型简化,从理论上证明绳锯机夹紧装置能够满足形封闭条件,可以使绳锯机稳定地固定在平台桩基上。分析绳锯机夹紧时的受力情况,根据最小值原理得出了绳锯机夹紧力求解的数学模型。按照水下绳锯机的实际工况对夹紧力进行求解,该结果为绳锯机的夹紧装置结构设计和液压系统设计提供理论依据。     

海洋废弃平台桩基拆除绳锯机多扰动定位夹紧力研究

海洋废弃平台桩基拆除绳锯机是一种复杂的机电设备,夹紧力的选择,直接关系到绳锯机的安全稳定工作。分析了桩基夹紧时的截面弯矩和变形量,得到了废弃平台桩基失稳临界力计算方法。利用有限元法分析了桩基夹紧时的变形和受力。采用非线性模型求解出了不同失稳临界力条件下的夹紧瓣夹紧力。实验表明,满足桩基不同失稳临界力条件下,绳锯机夹紧装置的夹紧力能够保证绳锯机安全工作。该结果为绳锯机的水下可靠性工作打下了一定基础。     

海洋废弃平台桩基拆除绳锯机夹紧力的阻抗控制策略研究

海洋废弃平台拆除过程中可以采用水下绳锯机切断桩基,适当大小的夹紧力是绳锯机安全稳定工作的前提条件。分析绳锯机夹紧力控制策略,建立绳锯机夹紧瓣夹紧桩基时的动力学方程,提出采用位置型神经网络阻抗控制方法来控制夹紧力,设计神经网络补偿器。根据绳锯机的实际工程样机,对多种情况下的力控制进行仿真研究,结果表明:位置型神经网络阻抗控制方法可以很好地补偿夹紧瓣动力学模型和位置的不确定性,适合于绳锯机夹紧力控制。     

海洋废弃平台桩基拆除绳锯机切割驱动性能研究

海洋废弃平台拆除过程中可以采用绳锯机切断桩基,适当大小的切割驱动力是绳锯机安全稳定工作的前提条件.介绍绳锯机工作原理,分析绳锯机平稳运行与非平稳运行过程中的切割驱动力计算方法.根据绳锯机的一些已知设计条件,采用非平稳运行时的算法计算了绳锯机的关键驱动几何参数.实验结果表明,由此参数设计的绳锯机能够满足实际桩基切割要求,同时分析了金刚石颗粒的存在对驱动过程的影响.     

海洋废弃平台桩基拆除绳锯机夹紧位姿控制研究

海洋废弃平台桩基拆除绳锯机工作前需要快速固定到桩基上,这是一个复杂的位姿调整过程,需要由夹紧装置来完成,由绳锯机夹紧液压缸同步控制,使位姿调整过程安全、稳定。分析得到了位姿调整的动力学模型;采用二级控制方法设计了控制系统,其中外环采用定量反馈控制理论,内环采用基于扰动观测的理论;进行了绳锯机位姿调整实验,结果表明:控制系统在误差范围内能够使液压缸同步,进而实现了位姿调整的工程目标,该结果为绳锯机水下高效可靠地工作打下了一定的基础。     

海洋废弃平台桩基拆除绳锯机驱动系统控制研究

伴随着海洋油气田多年的开采,越来越多的废弃平台需要分解处理,切割是非常重要的一道工序。平台水下桩基切割可以采用绳锯机来完成,考虑到桩基的直径较大,研发的绳锯机切割框架包含4个绳轮,其中驱动轮为相邻两个。为了安全高效切割,必须使两个驱动轮保持同步。建立驱动轮同步工作的动力学模型,提出同步耦合控制方法。结合绳锯机的实际结构,对控制方法进行仿真分析和实验研究。结果表明:该控制方法能够满足绳锯机的水下切割要求,为绳锯机的高效稳定工作打下了一定理论基础。     

基于粒子群算法的海洋废弃平台桩基拆除绳锯机夹紧力优化

水下绳锯机可以用来完成海洋废弃平台桩基切割。绳锯机切割过程中,当水下环境发生变化时,应能够较迅速地调整夹紧力以适应环境的改变。介绍绳锯机的夹紧数学模型,根据绳锯机的实际设计条件,采用粒子群算法对夹紧力进行快速的优化求解。通过实验表明,此方法获得的夹紧力能够使绳锯机稳定地工作,并且测得了相应的动态参数。研究结果为绳锯机夹紧力的水下环境快速自适应控制提供了一定的基础。     

海洋废弃平台桩基拆除绳锯机方案分析与研究

海洋石油开采基地平台被废弃后需要拆除,绳锯机是一种新型环保的水下切割工具,研发中可借鉴的技术、信息非常少,其合理方案的分析较困难。分析了一种灰色关联投影的I-QFD-E方法,根据绳锯机的技术研发指标,得到了绳锯机的质量要素,采用灰色关联投影的I-QFD-E方法对几种可行性方案进行了研究。根据研究结果选取了最优方案,研发了废弃平台桩基拆除绳锯机。通过实验表明,该绳锯机达到了预期要求,表明了该方法的合理性。     

海洋废弃平台桩基拆除绳锯机驱动组件关键参数研究

海洋废弃平台桩基拆除绳锯机是一种复杂的机电一体化设备,关键部位的密封直接决定了该设备的使用寿命。介绍了驱动轮轴承室的密封结构,分析得到了其主要部件在温度变化时的应力及尺寸变化数学模型,根据理论分析结果进行了实验研究。实验表明,温度变化对密封结构产生的影响必须要考虑,并且要对相关参数进行修正。该结果为绳锯机的密封组件关键参数选择提供了理论依据。     

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。