风电齿轮箱直齿轮传动系统动态特性影响分析

综合考虑齿轮啮合刚度、齿侧间隙、齿轮啮合误差以及外部激励等多种非线性因素对齿轮传动系统动态特性的影响,建立风电齿轮箱传动系统高速级直齿轮传动的纯扭转非线性动力学模型,用拉格朗日方程推导了传动系统的振动微分方程。采用Runge-Kutta法对直齿轮系统非线性动力学模型进行求解,得到传动系统的时域波形、频谱图和相位图。定量给出齿轮转速、齿侧间隙等参数变化对齿轮传动系统动态特性的影响。结果表明:随着转速和齿侧间隙的增大,传动系统的振动幅值明显增大,系统的振动加剧。为风电齿轮箱传动系统的固有特性,动态响应等动力学特性奠定了一定的基础。     

5MW风电增速齿轮箱的设计与动力学分析北大核心

针对大功率风电增速齿轮箱设计与研究不足的问题,提出5 MW级设计方案,并进行动力学分析。采用三级传动类型,前两级为2K-H型行星轮系,三级为定轴轮系。通过输入风电载荷谱进行仿真分析与理论计算结果对比,确保计算结果的准确性。利用动力学方法:对行星架进行模态分析,使行星架模态频率避开齿轮啮合频率;对各齿轮副进行传动误差分析,得出各齿轮副传动误差的周期性变化规律与最大误差;对各轴承进行加速度响应分析,得出不同转速下的振动加速度曲线,发现各轴承加速度曲线的波峰与波谷出现重叠的规律,使齿轮箱输入转速避开了峰值。研究内容为大功率风电齿轮箱设计与可靠性分析提供方法。     

斜齿轮的参数化建模及有限元模态分析

为提高斜齿轮设计的效率,提高其工作的可靠性,避免斜齿轮在传动系统中产生共振。采用了三维造型软件Pro/E实现斜齿轮的参数化建模,采用ANSYS有限元软件对斜齿轮进行有限元模态分析,研究斜齿轮的固有振动特性,得到了斜齿轮的低阶固有振动频率和主振型。所得的结论:斜齿轮的参数化建模,提高了斜齿轮设计的效率;模态分析得到的斜齿轮的低阶固有振动频率和主振型,反映了斜齿轮的动力学性能,在齿轮系统的设计中使工作频率远离齿轮的固有频率,避免发生共振,同时也为斜齿轮系统的动态响应计算和分析奠定了基础。     

轻载装载机变速箱振动特性分析与试验

为了给装载机变速箱减振降噪提供依据,通过集中参数和有限元法相结合的方式对变速箱进行振动分析。综合考虑液力变矩器激励、齿轮系统内部激励等因素,建立装载机变速箱传动系统的弯-扭耦合动力学模型,求解得到各轴承的动态支反力;建立箱体有限元模型,进行模态分析,以轴承动态支反力为激励,在模态的基础上进行箱体谐响应分析,得到箱体在激励下的振动响应,选择箱体表面的振动测点,分析测点的振动加速度,找到并分析振动峰值及对应振型;最后进行变速箱振动试验,验证仿真的正确性。结果表明：传动系统的激励主要集中在输入和输出平行轴齿轮处,传动系统和箱体振动的峰值频率均和齿轮啮合频率相近,变速箱箱体振动较大的位置位于箱体的底部。试验与仿真对比,试验中存在和仿真相近的峰值频率,仿真和试验所得的振动加速度均方根误差值小于20%,验证了仿真的正确性。     

基于正交试验的双圆弧齿轮约束模态模型研究北大核心

齿轮模态分析主要依靠数值模态分析和试验模态分析法,存在求解过程繁琐且无法直接获取齿轮参数与模态频率振型之间耦合关系的问题。为进一步掌握齿轮主要参数对约束模态频率的影响,根据模态有限元计算理论,对双圆弧齿轮约束模态模型进行研究;分析前6阶模态振型图,采用正交试验方法,运用方差分析,计算各因素对模态频率的影响因子;定量分析双圆弧齿轮的齿数、模数、螺旋角、齿宽因素对约束模态的影响。结果表明:齿数是影响固有频率的主要因素,其次是模数、螺旋角和齿宽;对试验结果进行中心化一次非线性回归模型计算,建立双圆弧齿轮约束模态频率计算模型,实现双圆弧齿轮约束模态的快速计算,对比验证1阶频率计算值的准确性。研究结果为全面研究双圆弧齿轮的振动和噪声特性提供参考。     

基于刚度矩阵单元的斜齿轮传动系统耦合振动有限元分析

推导了斜齿轮传动系统的轮齿啮合刚度矩阵;以及传动轴及支承的弹性变形,利用有限元法建立了考虑轮齿啮合刚度的斜齿轮传动系统的弯-扭-轴-摆耦合振动模型;计算了系统的耦合振动固有模态,并分析了轮齿啮合刚度及轴承支承刚度对系统动态特性的影响。     

基于有限元模态及ODS方法的棒材轧机主齿轮箱剧烈振动分析

国内某钢厂棒材生产线在生产12 mm规格棒材时,发现其棒材轧机精轧机组主齿轮箱振动异常,齿轮箱输入轴端的轴向振动幅值较大,频率为32.512 Hz;本文首先通过对棒材轧机齿轮箱整体模型进行模态分析,预估齿轮箱的动态特性,再建立试验测试模型并施加约束,进行ODS分析,得到齿轮箱在工作过程中真实的变形情况,最后结合有限元模态分析结果与ODS试验结果,确定轧机齿轮箱异常振动原因,并应用相关信号测试技术对结果进行了验证。     

行星轮系故障动力学仿真及其诊断软件开发

行星齿轮箱的诸多传动优点使其越来越广泛地被应用于诸多机械设备中,其振动响应比定轴齿轮箱更为复杂,相应的动力学模型建立及故障诊断成为近年来的研究难点和热点。建立了行星齿轮系统动力学模型;通过对行星齿轮系统动力学模型的求解,并利用MATLAB/Simulink模块对模型进行分析,得到了行星轮断齿时系统的频谱响应特性;同时,运用现代信号处理方法,以面向对象的程序设计语言Visual C++6.0和关系型数据库SQL Server为工具,建立故障诊断类型及信号处理方法数据库,将不同故障特征录入故障库,研究开发了一套行星轮系健康状态监测和故障诊断的软件。运用行星齿轮箱故障诊断实验台对所设计软件进行试验测试,通过试验信号的对比,验证了动力学模型分析结果的准确性以及该软件具有可用性和准确性。     

滚柱直线导轨副结合面参数识别与数值模拟

导轨副结合面静、动态特性对于机床整机性能有着显著的影响,导轨副结合面参数准确识别是机床整机性能预测的基础。国内现有导轨副设计方法落后,严重制约了机床功能部件及整机制造行业的发展。建立一种实用的滚柱直线导轨副动力学建模方法,采用有限元法对导轨副的自由和约束模态进行分析研究,并分别进行了实物模态特性测试,最后将仿真分析结果和实验测试结果进行对比。结果表明:仿真计算结果与试验结果的误差在8%以内,所建立的滚柱直线导轨副动力学模型具有较高的精度,可用于导轨副乃至机床整机特性预测。     

全悬挂转炉倾动机构高速级齿轮模态分析

为提高全悬挂转炉倾动机构高速级齿轮工作的可靠性,避免工作过程中发生共振,从动力学角度出发,建立高速级齿轮动力学模型,利用Pro/E建立三维实体模型并应用ANSYS在定义接触与不定义接触两种情况下对其进行振动模态分析,得到两者低阶振动的固有频率和固有振型,通过对比发现定义接触与不定义接触有着本质区别。分析齿轮参数,如模数、齿数、螺旋角等对模态的影响,为倾动机构的平稳工作提供依据。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.