铸造起重机端梁铰接轴联接固定结构的改进设计

八钢二炼钢区域的大吨位冶金铸造起重机为四梁四轨双小车结构,在使用过程中出现连接固定失效、铰接轴非正常磨损的情况。起重机端梁铰接点连接失效会造成起重机主梁与副梁分离的严重设备事故。介绍了对原设计的结构方式进行的改进设计,改进后消除了铰接连接失效的事故隐患。     

VOLVO铰卡前车架铰接销孔衬板故障分析与处理

VOLVO矿用铰接式卡车是一种通用性强的土方运输车辆。由于铰接机械结构,该铰接式卡车在恶劣的气候、地形等复杂情况下具有很高的实用性。前后连接的铰接器是VOLVO铰接式车的关键部件,后车架带有永久润滑滚子轴承的旋转铰链连接。作为车辆关键连杆部件的前车架铰链销孔和销轴比其他机械部件更容易磨损。因此,铰接器机械部件在恶劣的条件下承受沉重的负荷,前车架铰链销孔与销轴的连接部位易受到外力、重心叠加等复合载荷的影响,导致铰链销孔衬板变形、开裂、销轴异常等故障频发,对设备利用率和运行安全造成不利影响[1]。本文将通过分析和处理,提高设备的利用率,解决安全隐患,降低生产成本。     

基于不确定性的铰接式自卸车铰接体的多工况拓扑优化

以均匀化方法为理论基础,对铰接式自卸车的铰接体进行多载荷工况下的拓扑优化研究.在确定各工况权重时,综合考虑权重本身的不确定性和专家可信度,利用盲数理论对专家的意见进行了不确定性的量化表示进而求出权重,并把权重值应用到多工况拓扑优化中,最后对铰接体的结构进行了可靠性分析,所得结果证明基于盲数理论取得的权重的合理性.     

正交胶合木填充墙-钢框架体系受力性能

采用开源地震工程模拟系统（OpenSees）对以正交胶合木作填充墙的钢框架结构进行探索性数值研究,主要研究该填充墙钢框架单元在单调和循环加载作用下的受力性能,墙体与钢框架之间的协同工作性能以及连接个数对整体结构受力性能的影响.结果表明：正交胶合木填充墙能够提高钢框架的抗侧刚度和水平承载力;柔性连接的设置使整体结构耗能性能良好;工作缝的设置减缓墙体的开裂,更大程度上发挥连接件的耗能和变形能力;连接个数对构件的抗侧能力影响较大,可以通过调整连接数量和连接间距设计出具有多种刚度和耗能能力的框架单元.     

起重机端梁铰轴结构改进

介绍了冶金行业中四梁双小车铸造起重机,主梁与端梁连接采用铰接型式。端梁铰处零件磨损后更换时间长,影响生产效率。提出端梁铰轴结构型式的改进和优化方案,缩短检修维护时间,提高生产效率。     

新型三重钢管防屈曲耗能支撑的力学性能

基于在大跨网架结构中的应用,对目前的三重钢管防屈曲耗能支撑进行改进,设计了一种新型支撑,并对该支撑考虑初始缺陷下的力学性能进行了理论分析.根据理论分析,设计了四组不同的支撑,利用ABAQUS有限元软件模拟分析了在拉压循环荷载作用下支撑强度比对其力学性能的影响,包括连接段应力状态、滞回耗能能力和核心管屈曲破坏模式.研究结果表明：该新型耗能支撑结构布置可行,设计方法合理,强度比是影响支撑力学性能的重要参数,在强度比合理范围内,支撑具有良好的滞回耗能性能;在轴向循环荷载作用下,内外套管约束作用明显,核心管破坏模式为多波小幅屈曲破坏,变形稳定,满足防屈曲支撑设计要求.     

某空旷大跨度体育场馆的建模分析

针对体育场馆类空旷大跨度结构的设计特点,运用有限元程序,对某公司文化体育中心结构的整体受力性能、薄弱部位及大跨度网架屋盖对主体结构受力性能的影响与协同工作等问题进行了模拟分析.计算表明,此类结构具有扭转不规则性,薄弱部位常出现在空旷结构部位和弱连接部位;空旷框架部分存在相对变形大的现象.由于框架柱缺乏有效约束,其计算长度较大,P-△效应明显;网架屋盖在水平力及地震作用下对主体结构有不可忽视的作用,应考虑网架屋盖与下部框架结构的协同工作.实际设计中可考虑将网架部分按照一定的规则等代为钢梁,来近似考虑网架的刚度进行整体设计.     

济钢宽厚板3500产线双边剪结构改造

双边剪自投用以来存在主刀剪切机构稳定性差、碎刀剪切机构损坏严重、后退机构故障频繁等问题。对其进行技术改造,将主刀间隙调整偏心轴三段式分体结构改为整体通轴结构,适当增加碎刀间隙调整的偏心量,夹送辊与机架的联接方式改为轴偏心铰接结构。改造后,双边剪运行稳定,故障率明显降低,能够满足正常使用要求。     

考虑支架变形影响的大型脱硝反应器及烟道结构数值分析

以某电厂的脱硝工程为背景,对烟道、反应器和支架这种大型复杂结构进行了整体分析,并以烟道出口和反应器作为研究对象,分析了支架变形对烟道出口和反应器的影响.结果表明,由于支架变形的影响,烟道和反应器的变形分布由对称分布变为非对称,平均变形值要比不考虑时的大,但是支架的变形对烟道和反应器的应力值及分布基本无影响.因此在以强度为控制因素的设计中,烟道和反应器进行单独计算的设计方法是可行的.     

预制钢筋混凝土地上综合管廊的研究与设计

详细介绍了地上综合管廊的发展及现状,着重论述了预制钢筋混凝土管廊的结构形式与组成,对预制钢筋混凝土管廊的受力中较复杂的水平荷载进行了阐述,并对钢筋混凝土管廊的预制构件进行了拆解,给出了预制钢筋混凝土管廊的铰接与固接连接支座形式。系统阐述了预制钢筋混凝土管廊支架的整个设计流程和基本解决方案,供实际工程应用参考。     

波轮式脱水机甩干桶爆裂原因及有限元模拟分析

消费者反馈信息表明某品牌的脱水机甩干桶在用户使用过程会发生爆裂事故,为分析事故发生的原因,实验对事故品牌的脱水机和对比品牌的脱水机进行了一系列试验,应用拉伸试验、压力试验、接缝区剖面结构分析以及有限元仿真模拟等研究了脱水机甩干桶的爆裂原因和甩干桶内壁的应力分布。拉伸试验和压力试验结果表明,事故甩干桶的接缝处结合力很薄弱,仅为正常桶身强度的13%,而对比品牌的甩干桶接缝区的强度与桶身的强度相当,大约是前者的5.7倍。接缝区剖面结构分析表明,两甩干桶的接缝方式不同是造成二者强度存在差异的原因,前者为卷压式连接,后者采用了焊接方式。应用有限元分析了甩干筒的应力分布,结果表明,事故品牌的甩干桶接缝处的应力水平偏高,在相同工作条件下其发生开裂的风险远高于对比品牌的接缝处。试验分析和有限元理论计算均表明,事故品牌甩干桶的卷压连接处结合力偏低是造成其发生爆裂的主要原因。     

Stress Spikes in Pin and Hanger System of Truss Bridge

Several functional problems have been reported on pin and hanger system truss bridges, such as frozen pins, stress spikes in hangers, lack of expansion joint movements, etc. It has been difficult to develop a pin and hanger retrofit strategy because the cause for the observed problems is usually unknown. This paper presents a study performed on the pin and hanger system of one such bridge—the Newburgh Beacon bridge. Extensive field testing performed so far has failed to identify the cause for the observed stress spikes. The concept of misalignment loading is developed in this article to explain the observed behavior. Stress spikes predicted using this concept matched very well with the observed stress spikes. Finally, the use of misalignment loading to evaluate other truss members is also discussed.     

中厚板轧机十字轴结构优化

针对济钢中厚板厂3200mm四辊粗轧机万向节十字轴的失效原因,采用有限元的分析方法,对十字轴的结构进行研究和优化,这对于提高中厚板轧机主传动轴万向节的承载能力具有重要意义。     

Investigation on the Failure Mechanism of DP590-22MnB5 (Quenched) and DP590-DP590 Spot-Welding Joints

The failure mechanism of DP590-22MnB5(quenched) and DP590-DP590 spot-welding joints is studied through lap-shearing experiments,metallographic observation and three-dimensional finite element simulation.Both joints cracked on the DP590 steel,but the tensile shear strength of the DP590-22MnB5(quenched) joint is greater than that of the DP590-DP590 joint.A finite element model for the lap-shearing experiment is established according to the mechanical properties of DP590 and 22MnB5(quenched) steels and the metallographic analysis of welding spots.The simulation results show that the difference in the axis rotation of the two welding spots causes different distributions of stress and strain,which shifts shear loading condition to opening loading condition.Due to larger axis rotation angle of the DP590-DP590 joint,the stress concentration occurs at the middle of the nugget circumference,and it results in lower tensile shear strength of the DP590-DP590 joint.     

Accuracy assessment of methods for determining hip movement in seated cycling

The goal of this research was to examine the accuracy of three methods used to indicate the hip joint center (HJC) in seated steady-state cycling. Two of the methods have been used in previous studies of cycling biomechanics and included tracking a marker placed over the superior aspect of the greater trochanter, a location that estimates the center of rotation of the hip joint, and assuming that the hip is fixed. The third method was new and utilized an anthropometric relationship to determine the hip joint location from a marker placed over the anterior-superior iliac spine. To perform a comparative analysis of errors inherent in the three methods, a standard method which located the true hip joint center was developed. The standard method involved establishing a pelvis-fixed coordinate system using a triad of video markers attached to an intracortical pin. Three-dimensional motion analysis quantified the true hip joint center position coordinates. To provide data for the comparative analysis, the intracortical pin was anchored to a single subject who pedaled at nine cadence-workrate combinations while data for all four methods were simultaneously recorded. At all cadence-workrate combinations the new method was more accurate than the trochanter method with movement errors lower by a factor of 2 in the vertical direction and a factor of 3 in the horizontal direction. Relative to the errors introduced by the fixed hip assumption, the new method was also generally more accurate by at least a factor of 2 in the horizontal direction and had comparable accuracy in the vertical direction. For computed kinetic quantities, the new method most accurately indicated hip joint force power but the fixed hip method most accurately indicated the work produced by the hip joint force over the crank cycle.     

Percutaneous pinning of proximal humerus fractures: a biomechanical study

Mechanical testing of two-part surgical neck fractures fixed with four different pin configurations was performed. Ten fresh, frozen, unembalmed humeri stripped of all soft tissues were used; the surgical neck was osteotomized perpendicular to the humerus long axis. Terminally threaded 2.5-mm AO pins were used to fix the fracture. Humeri then were tested in both torsion and bending on a custom-made jig using Instron 1331 to assess the rigidity of pinning constructs. In torsion, two lateral pin construct was significantly less rigid than all other pin configurations. The addition of an anterior pin to two lateral pins did not increase bending rigidity, but significantly increased torsional stiffness. The addition of two bicortical tuberosity pins or two bicortical tuberosity pins and one anterior pin to two lateral pins significantly increased rotational and bending rigidity. Results confirm clinical data, and the authors conclude that multiplanar pins are needed to augment torsional stiffness, and that the addition of two bicortical tuberosity pins enhances bending rigidity.     

Characterization of the Influence of Tool Pin Profile on Microstructural and Mechanical Properties of Friction Stir Welding

In this study, the effect of tool pin profile on mechanical properties, microstructural, material flow, thermal and strain distributions of friction stir welding of AA5083 was investigated. Two different tools with cylindrical and square pin profiles were employed to produce the welds. A numerical model is developed for investigating the effect of tool pin profiles on material flow, thermal and strain distributions based on thermo-mechanically coupled rigid-viscoplastic 3D FEM. Then, optical microscopy was employed to characterize the microstructures features of the weld. Finally, tensile test was carried out to characterize the mechanical properties of the weld. Obtained results showed that square pin profile produced finer grain structure and higher ultimate strength relative to cylindrical one. These results may be related to higher eccentricity, larger stirred zone, and higher temperature in the weld zone of the square pin profile.     

一个由Mckibben肌肉驱动的类人关节

建立了一个类人的机器人关节,由两条对抗设置的Mckibben人工肌肉驱动.简单介绍了Mckibben肌肉的力特性模型,推导了关节角度和Mckibben肌肉长度间的关系,从力学角度讨论了最大可能旋转角度,分析了Mckibben肌肉与关节的连接位置及关节结构参数对关节旋转角度的影响,并把类人关节和人类关节进行了比较.结果表明,Mckibben肌肉的收缩率和关节结构参数对关节旋转角有较大影响,关节内侧的Mckibben肌肉与关节的适中连接位置可使关节角达到极大值.     

Estimating the working life of steel beams on the basis of their mechanical properties

Forged steel 50 rollers are used in the roughing group of wire and small-rod mills. In intense rolling, the roller pin often breaks, since the pin experiences the maximum stress. It is established that the fracture is of fatigue type, and three disintegration zones are identified. Crack propagation is due to the stress in the crack tip. The rate of crack propagation in cyclic loading depends on the structure of the metal, the grain size, and the mechanical properties of the rollers. The unbroken rollers are characterized by high values of the impact strength, initial and final temperatures of ingot forging, and σ_y/σ_B. An empirical dependence of the number of roller rotations to pin fracture on the mechanical properties of the material and the loads is established. Small-grain structure of the metal matrix and purity of the metal ensure a good combination of strength and plasticity.     

Analysis of Effect of Gas Temperature on Cooling Stave of Blast Furnace

In order to study the effect of gas temperature variation on cooling stave,temperature,stress and displacement distributions of cooling stave were analyzed respectively when gas temperature inside blast furnace increases from 1000 to 1600℃.The results show that the temperature field on cold side is under control of cooling pipes and hardly changes when gas temperature increases.The temperature gradient and change rate with time near hot sides are greater than those in other regions and the later can reach 100℃/s.The stress intensity near middle area of hot surface is up to 400MPa and that's why there are lots of cracks at this place.The edge of stave is bent to cold side and middle regions between fixed bolts and pin moves to hot side.The displacement around fixed pin is smaller but larger on the edge and the maximum is located on hot side of top surface.The maximum displacement in z direction is about 4mm and 3mm in y direction.If the expansion coefficient of packing layer is 1/4,the thickness of packing layer between the cooling staves is 32mm and 24mm between sides up and down.