界面对硅酸铝短纤维增强AZ91D镁基复合材料蠕变性能的影响

界面对复合材料蠕变性能的影响很大。在试验分析的基础上建立了硅酸铝短纤维增强AZ91D镁基复合材料理论分析模型,利用三维有限元分析方法,系统研究了界面特性、界面上应力应变分布和短纤维位向变化对硅酸铝短纤维增强AZ91D镁基复合材料蠕变性能的影响。研究表明：界面特性,如厚度、模量,均对纤维最大轴应力和稳态蠕变速率有影响,当界面厚度增加,纤维最大轴应力减小而稳态蠕变速率增大;当界面模量增大,纤维最大轴应力增大而稳态蠕变速率减小,但当界面模量高于基体模量时,纤维最大轴应力和稳态蠕变速率均保持不变;纤维位向也影响轴应力分布和稳态蠕变速率,纤维在其末端界面上存在较大的应力和应变,此处容易产生微裂纹而使材料抗蠕变能力下降;界面对硅酸铝短纤维增强AZ91D镁基复合材料的蠕变曲线和蠕变断裂机制也有影响,其影响程度还与纤维位向有关。     

用二次谐波检测舰船电场的研究

提出一种测量舰船电场的新方法，即用二次谐波方法测量大轴周围磁场，从而确定大轴电流，进而分析由大轴电流带来的舰船电场，理论和实验均表明，该方法结构简单，构思精巧，是检测舰船电场的方法之一。     

汽轮机大轴弯曲的原因分析与事故处理

简单介绍了我公司汽轮发电机组的基本情况，阐述了汽轮机大轴弯曲对汽轮机安全经济运行的危害，针对汽轮机大轴弯曲的问题，从各个方面进行分析，找出大轴弯曲的原因，并提出相应的事故处理及预防措施。     

汽轮机大轴弯曲事故现象与预防处理措施

文章介绍了防止汽轮机大轴弯曲的一些要求，针对如何预防处理汽轮机大轴弯曲事故进行了阐述。     

土体力学性质对输气管道穿越地震断层的影响分析

为获取土体力学性质对输气管道应变行为的影响,给出等效边界弹簧设置在管道弹塑性变形段的本构关系,并据此建立考虑等效边界弹簧的输气管道穿越地震断层壳-接触有限元模型。利用该有限元模型,分析地震断层作用下土体力学性质对输气管道受拉侧和受压侧最大轴向应变的影响规律。结果表明:在较小的断层位移下,土体弹性模量和内摩擦角对最大轴向应变有较大影响;随着断层位移的增大,土体弹性模量和内摩擦角对最大轴向应变的影响降低。无论较小断层位移还是较大断层位移,土体内聚力对输气管道最大轴向应变的影响均较小。     

汽轮机大轴弯曲的原因及防治措施

汽轮机大轴弯曲是汽轮机恶性事故最典型的一种,这种事故多出现在高参数大容量的汽轮机中,破坏性极其严重,对这一事故的防治尤其重要。     

基于虚拟仪器界面的大轴轴线直线度误差测量系统

提出了一种基于虚拟仪器界面供生产现场使用的高精度、高效率的大轴轴线直线度误差测量系统。     

四种激光照排片性能对比

1　测试样品1)爱德发HS激光照排片———Agfa公司生产的大轴胶片 ,深圳中创实业公司分装。2 )爱尔发HNG激光照排片———Agfa公司生产的大轴胶片 ,深圳中创实业公司分装。3)意大利HR激光照排片———意大利生产的大轴胶片 ,国内分装。4 )华光RL—ⅡN型激光照排———中国乐凯胶片集团公司第二胶片厂生产。2　测试项目　　●防光晕层状况 (见表 1)表 1　防光晕层的颜色和吸收曲线对比品牌 爱德发HS爱尔法HNG意大利HR华光RL -ⅡN颜色湖蓝墨绿绿色深蓝吸收范围 (nm) 60 2～ 70 0 5 60～ 70 0 5 60～ 70 0 5 3 5～ 73 0λmax(nm) 65 0 …     

多滚轮法大轴径测量的相关性分析

在高精度多滚轮法大轴径测量中,通过对三个滚轮的冗余测量信号进行相关性分析,辨识出测量过程中的打滑发生段.最后用matlab进行仿真证明了此方法的有效性.     

柔性抗震承插式铸铁排水管道的施工

柔性抗震承插式铸铁排水管,简称WD管,能在较大轴向伸缩位移、振动位移和较大轴向挠度变形条件下保持正常工作,得到广泛应用,文章对其施工要点做了叙述.     

Fracture analysis of wind turbine main shaft

Shaft fracture at an early stage of operation is a common problem for a certain type of wind turbine. To determine the cause of shaft failure a series of experimental tests were conducted to evaluate the chemical composition and mechanical properties. A detail analysis involving macroscopic feature and microstructure analysis of the material of the shaft was also performed to have an in depth knowledge of the cause of fracture. The experimental tests and analysis results show that there are no significant differences in the material property of the main shaft when comparing it with the Standard, EN10083-3:2006. The results show that stress concentration on the shaft surface close to the critical section of the shaft due to rubbing of the annular ring and coupled with high stress concentration caused by the change of inner diameter of the main shaft are the main reasons that result in fracture of the main shaft. In addition, inhomogeneity of the main shaft micro-structure also accelerates up the fracture process of the main shaft. In addition, the theoretical calculation of equivalent stress at the end of the shaft was performed, which demonstrate that cracks can easily occur under the action of impact loads. The contribution of this paper is to provide a reference in fracture analysis of similar main shaft of wind turbines.     

火电机组给水前置泵轴断裂原因分析

某火电厂4号机组B给水前置泵轴投运仅19h即发生断裂。经对断裂泵轴进行宏观分析、化学成分分析、常温力学性能测试、金相检验及断口扫描电镜分析,探讨并明确了泵轴断裂原因,同时提出了防范措施。结果表明：该给水前置泵轴断裂为疲劳断裂,在弯曲及扭转载荷作用下于变截面的应力集中部位的不连续及夹杂物处形成疲劳裂纹,同时大量夹杂物及沿晶分布的粗大a铁素体的存在严重降低了基体强度,使轴体所能承受的循环应力大大降低,即在较低的循环应力作用下疲劳裂纹不断扩展并最终断裂。     

齿轮箱轴断裂分析

采用化学成分分析、断口分析、金相检验和力学性能测试,对某齿轮箱轴发生断裂的原因进行了分析。结果表明：其断裂模式为疲劳断裂,起源于退刀槽尖角位置,直角退刀槽造成应力集中产生疲劳裂纹;而原材料的锻造和热处理工艺不合理,加速了轴的疲劳断裂。     

坦克扭力轴表面缺陷对疲劳寿命的影响

为探求坦克扭力轴过早产生疲劳断裂的原因,应用弹性有限元方法模拟了坦克扭力轴表面各种形状、尺寸的凹坑处产生的应力集中现象,结合坦克在某一训练科目下的载荷谱,使用疲劳分析软件计算了具有不同形状和尺寸缺陷的扭力轴的疲劳寿命(存活率为99%).结果表明:一旦扭力轴表面出现了凹坑,尤其是出现了狭长的裂纹状凹坑时,其疲劳寿命会急剧下降;当出现狭长的裂纹状凹坑时,将其扩展成等径凹坑(不增大凹坑深度),可使凹坑对扭力轴疲劳寿命的影响降至最低.     

Failure Analysis of Reverse Shaft in the Transmission System of All-Terrain Vehicles

This paper presents a failure analysis of a reverse shaft in the transmission system of an all-terrain vehicle (ATV). The reverse shaft with splines fractured into two pieces during operation. Visual examination of the fractured surface clearly showed cracks initiated from the roots of spline teeth. To find out the cause of fracture of the shaft, a finite element analysis was carried out to predict the stress state of the shaft under steady loading and shock loading, respectively. The steady loading was produced under normal operation, while the shock loading could be generated by an abrupt change of operation such as start-up or sudden braking during working. Results of stress analysis reveal that the highest stressed area coincided with the fractured regions of the failed shaft. The maximum stress predicted under shock loading exceeded the yield strength and was believed to be the stimulant for crack initiation and propagation at this weak region. The failure analysis thus showed that the premature fatigue fracture of the shaft was caused by abnormal operation. Finally, some suggestions to enhance service durability of the transmission system of ATV are discussed.     

电厂外供泵轴断裂原因分析

某外供泵在运行期间其泵轴发生断裂。通过宏观和微观检验、化学成分分析以及硬度测试等方法对泵轴断裂的原因进行了分析。结果表明:该轴的热处理没有达到要求,使各项强度指标显著降低,加上在应力集中部位键槽根部产生了疲劳裂纹,并进一步扩展,最终导致泵轴断裂。     

Failure of two overhead crane shafts

The failure analysis of two overhead crane shafts is presented: the failure of an overhead crane drive shaft and the failure of an overhead crane gearbox shaft, due to rotating-bending fatigue. The fracture of the overhead crane drive shaft originated in small radius fillet between two different diameters of the shaft. A new shaft was made with a larger-size fillet, resulting in reduced stress concentration in this region. The failure of the overhead crane gearbox shaft originated at the intersection of two stress raisers, at the change in shaft diameter and in the keyway corner. A new shaft was made with a larger-size fillet and a larger size radius of the keyways corner to minimize stress concentration in this section. In both cases the installed couplings were replaced by gear couplings in order to allow parallel and angular misalignment as well as to avoid additional load due to misalignment. The analysis shows that the fatigue life can be significantly increased with a simple change in the structural details.     

HXD1机车牵引电机转轴组件断裂失效分析

HXD1型电力机车的牵引电机转轴和小齿轮轴采用圆锥过盈配合传动结构(下称转轴组件),使用中该组件出现了早期断裂失效.本文通过理化检测、断口和配合面宏/微观形貌观察等失效分析技术对失效组件进行了分析.结果表明,材料成分、组织和显微硬度正常,小齿轮轴和电机转轴的失效形式分别为高周疲劳断裂和微动疲劳断裂.造成组件失效的原因和过程是,小齿轮轴近齿端油槽-油孔交界线处有较大的结构应力集中,油槽底部周向加工刀痕造成附加应力集中,在应力集中和旋转弯曲疲劳载荷作用下油孔边两个应力集中点萌生了疲劳裂纹并扩展;随小齿轮轴裂纹的不断扩展转轴组件结构刚度减小,继而诱发了与小齿轮轴匹配的电机轴配合面的微动疲劳,电机轴疲劳裂纹萌生于微动区的边缘处;电机转轴先于小齿轮轴完全断裂.基于本文的分析结果提出了提高组件抗疲劳断裂的技术措施.     

压力机偏心齿轮主轴断裂分析

采用扫描电镜及光学显微镜对压力机偏心齿轮主轴断口进行了系统的分析。确定了主轴断裂属于疲劳断裂,并具有低周疲劳断裂的特征。找出了齿轮主轴断裂的主要原因－主轴油孔处的奕力集中以及超负荷运行造成轴的工作应力过大引起断裂。     

Failure Analysis of Spline Shaft in Beco Lathe

The failure of Heavy Duty Facing Lathe has been systematically investigated using fractographic, metallographic, and analytical stress analysis methods. Failure occurred during machining of a large flange, the tool post had a collision with jaw of the rotating chuck and the spline shaft inside headstock was broken into two pieces. A detailed analysis of the fracture surfaces revealed partial damage of the surfaces due to their rubbing in operation and cleavage fracture in the remaining part of the surfaces. The stress analysis indicates that sudden reversing of the spindle had resulted in the stresses exceeding the fatigue limit of the shaft material. These stresses led to the formation of microcracks at the circlip groove. The collision accelerated the sudden failure of shaft. This failure analysis has led to identification of root cause and its elimination with corrective measures undertaken.