压力管道可靠性安全评定

针对管道的断裂失效模式以及安全评定过程中存在的不确定性,提出了压力管道可靠性安全评定方法。通过分析主要评定参数：缺陷尺寸、工况载荷、断裂韧性、机械强度的分布特征,对各随机变量模拟实际工况抽样,应用Monte Carlo数值计算方法确定管道上的各独立缺陷的失效概率,进而获得整个管道的失效概率。可靠性安全评定方法确实反映了评定参数客观存在的不确定性,克服了确定性安全评定方法的缺点,具有极大的应用价值。     

基于概率断裂力学的管道失效分析

针对油气管道的断裂失效模式以及失效分析过程中存在的不确定性,结合概率断裂力学和安全评定规范,提出了管道缺陷失效概率计算方法。根据主要评定参数：缺陷尺寸、工况栽荷、断裂韧性、机械强度的分布特征,对各随机变量模拟抽样,应用Monte Carlo数值计算方法确定管道上各缺陷的失效概率。可靠性失效评定方法确实反映了评定参数客观存在的不确定性,克服了确定性失效评定方法的缺点,具有极高的应用价值。     

海底管道连接工艺研究

海底管道连接是构建完整的海底管道系统不可或缺的作业环节。文中介绍了海底管道连接所需机具,对各种连接器优缺点进行了比较分析,详细阐述了管道连接工艺流程,包括连接定位测量、水上预制、跨接管及作业机具下放、水下连接等,最后对不同连接方法进行了总结和比较。     

窗式空调器管道振动的控制与疲劳寿命估算

针对窗式空调器的蒸发器管道和冷凝器管道的振动问题，从力和变形的角度分析比较了几种不同弯曲形状的管道的刚度和弯矩，并根据管道振动产生的疲劳损伤预估其寿命，最后研究了压缩机对管道激起的振动，提出了控制管道振动，降低噪声的技术方法。     

疲劳载荷的平均处理及再现

以300t转炉吹炼时耳轴的实测切应力为例, 通过分析载荷幅值和均值的统计特性, 提出了一种随机疲劳载荷的平均处理方法, 并使用Monte carlO法实现了平均载荷的再现。     

用断裂力学法估算焊接钢结构的疲劳寿命

针对焊接钢结构的特点,指出了传统疲劳寿命估算方法中的缺点,并运用断裂力学的理论总结出估算焊接钢结构疲劳寿命的计算步骤,以实例说明该方法的优越性和可操作性。     

基于美国ASME标准的岸桥疲劳寿命估算

提出了适用于桥机焊接结构的疲劳寿命估算方法———结构应力法,此方法不必进行接头类型的分类,更具有通用性,在雨流计数过程中采用了一种新的方法,可以不对数据进行整个时间历程的整理,大大提高了计算速度。本文总结了适用于桥机的多种疲劳寿命计算方法,分析比较了其优缺点,以Matlab为平台编制了疲劳监测预警软件,可方便用户直接应用于现场监测。     

海底管道内腐蚀防护措施探讨

阐述了海底管道内腐蚀的原因,结合工程实际,就非金属复合管的海底管道内腐蚀防护措施进行了探讨,具有一定的参考价值.     

抛锚作业撞击海底管道的概率与影响

在海底管道所受到的各种损害中,抛锚作业撞击属于一种偶然性的载荷破坏,但是很容易导致海底管道受到破坏。本文阐述了抛锚作业撞击海底管道的概率,分析了海底管线被锚击中后的损害程度,并以工程为实例进行探讨,提出了应对措施,为进一步研究分析海底管道在偶然荷载作用下的影响打下了基础。     

Prediction of fatigue life distribution of marine propeller materials

Engineering materials have been studied and developed for a remarkably long time, but there are few reports about marine propeller materials. Recently, some researchers have studied the material strength of marine propellers. However, studies on parametric sensitivity and probabilistic distribution of fatigue life of propeller materials have not yet been carried out. In this study, we have evaluated strength characteristics of AlBC3 and HBsC1, both of which have been used for marine propellers using air jet chisel. Then a method to predict the probabilistic distributions of fatigue life of propeller materials is presented and the influence of several parameters on the life distribution is discussed. This paper was recommended for publication in revised form by Associate Editor Jooho Choi Han-Yong Yoon received his B.S. degree in Mechanical Engineering from DanKook University in Seoul, Korea, in 1981. He then received his M.S. and Ph.D. degrees from The University of Tokyo in Tokyo, Japan in 1985 and 1988, respectively. Dr. Yoon is currently a Professor at the Department of Mechanical Engineering at Mokpo National University in Jeonnam, Korea. And, he serves concurrently as the director of Library at his University. His research interests include reliability, fatigue, and fracture mechanics. Jianwei Zhang received his B.E. degree from the School of Electro-Mechanical Automobile Engineering from Yantai University, China, in 2005. He then received his M.E. from the Department of Mechanical Engineering Graduate School of Mokpo National University, Korea, in 2008. Mr. Zhang is currently studying for his doctorate at the Department of Mechanical Engineering, Graduate School of Mokpo National University, Jeonnam, Korea. His research interests include metal fatigue, weld residual stress, and composite materials fatigue.     

Prediction of the fatigue life of pneumatic tires

A method of the prediction of the fatigue life for parts of pneumatic tires based on the computation of the stress-strain state of the stress concentration areas in a rubber matrix and the self-heating temperature by means of the finite-element method and experimental fatigue curves for rubbercord composites has been developed. Multiple tensile tests of single-layer rubber-cord samples with a squared shape have been carried out, and fatigue curves under various test conditions and types of stress-strain states have been constructed. The fatigue life of the area of the edges of a breaker strip of a 9.00R20HC12 tire under a maximum working load and other parts of pneumatic tires is determined.     

A fatigue and low-energy shock-based approach to predict fatigue life

A product that is characterized by fatigue-induced failure always suffers from complex fatigue loads, and the damage caused by fatigue loads accumulates with time. The existence of shocks not only directly increases the risk of failure but also affects the magnitude of damage caused by fatigue loads. This study analyzes the reliability of a product when fatigue loads and shocks are both involved. The features of fatigue damage and shock damage are investigated, and the coupling relationship between them is discussed. With assumptions of high cycle fatigue and low-energy shocks, the effect of shocks on fatigue damage is expressed as the degradation of the ultimate strength of the product. An overall reliability model with fatigue and shock failures is developed. Two conditions are considered for the reliability model: shocks with fixed period and shocks with a homogeneous Poisson process. Three important cumulative damage theories are adopted. An engineering case of actuator cylinder is provided to demonstrate the proposed approach.     

Heat aging effects on the material property and the fatigue life of vulcanized natural rubber, and fatigue life prediction equations

When natural rubber is used for a long period of time, it becomes aged; it usually becomes hardened and loses its damping capability. This aging process affects not only the material property but also the (fatigue) life of natural rubber. In this paper the aging effects on the material property and the fatigue life were experimentally investigated. In addition, several fatigue life prediction equations for natural rubber were proposed. In order to investigate the aging effects on the material property, the load-stretch ratio curves were plotted from the results of the tensile test, the compression test and the simple shear test for virgin and heat-aged rubber specimens. Rubber specimens were heat-aged in an oven at a temperature ranging from 50°C to 90°C for a period ranging from 2 days to 16 days. In order to investigate the aging effects on the fatigue life, fatigue tests were conducted for differently heat-aged hourglass-shaped and simple shear specimens. Moreover, finite element simulations were conducted for the specimens to calculate physical quantities occurring in the specimens such as the maximum value of the effective stress, the strain energy density, the first invariant of the Cauchy-Green deformation tensor and the maximum principal nominal strain. Then, four fatigue life prediction equations based on one of the physical quantities could be obtained by fitting the equations to the test data. Finally, the fatigue life of a rubber bush used in an automobile was predicted by using the prediction equations, and it was compared with the test data of the bush to evaluate the reliability of those equations.     

Reliability prediction of the fatigue life of a crankshaft

Crankshaft, the core element of the engine of a vehicle, transforms the translational motion generated by combustion to rotational motion. Its failure will cause serious damage to the engine so its reliability verification must be performed. In this study, the S-N data of the bending fatigue limit of a crankshaft are derived. To evaluate the reliability of the crankshaft, reliability verification and analysis are performed. For the purpose of further evaluation, the bending test of the original crankshaft is carried out, and failure mode analysis is made. The appropriate number of samples, the applied load, and the test time are computed. On the basis of the test results, Weibull analysis for the shape and scale parameters of the crankshaft is estimated. Likewise, the B10 life under 50% of the confidence level and the MTTF are exactly calculated, and the groundwork for improving the reliability of the crankshaft is laid. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Do-Hyun Jung received his B.S. and M.S. degrees in Mechanical Engineering from Ajou University in 1988 and 1990, respectively. He then obtained his Ph.D. degree from Changwon National University in 2006. Dr. Jung is currently an Adjunct Professor at the School of Mechanical Engineering of Sunmoon University, Korea. He also manages the Reliability Application Research Center of the Reliability Division of KATECH. Dr. Jung’s fields of study include fatigue, reliability, and remanufacturing issues.     

基于有限元的织机综框边杆的疲劳寿命

针对JAT610织机综框边杆的疲劳断裂,用ANSYS有限元软件进行分析,结合应力实测的结果,得出了边杆应力集中产生疲劳的结论,对边杆的疲劳寿命进行了分析计算,结果与实际符合良好。     

Statistical modeling of the life of an oil pipeline under torque

The distribution of the pipe life in a weld-joint zone subject to torque is determined by statistical modeling, on the basis of a determinate formula in which the arguments are independent random quantities. As a result, the oil-pipeline reliability may be predicted, with environmental benefits.     

多轴低周疲劳寿命预测软件

通过Visual Basic6.0各种控件和算法的运用，编制的“多轴低周疲劳寿命预测软件（MLCFP1.0）”，涉及多种疲劳寿命预测方法，特别适用于结构中出现非比较、多轴应力状态的情况，为多轴疲劳下的寿命预测提供了解决的有力工具。本软件还留有新模型的嵌入接口，数据处理过程实现多文件操作。后处理绘图软件LCF FIGURE1.0，能给出标准的疲劳寿命预测图形，其保存文件形式多样。     

机械零件疲劳寿命问题研究

本文介绍了疲劳寿命问题的概念、发展历程,论述了疲劳寿命设计思想的变革过程,并指出了机械零件疲劳寿命问题研究的趋势是利用计算机的虚拟技术实现构件的寿命预测。软件的虚拟寿命分析设计与实验的有机结合可以节约实验成本,缩短设计周期。笔者认为机械零件疲劳寿命问题研究应从有限元的基本原理等理论基础入手,以某种成熟软件(如ABAQUS等)为辅助手段,利用工科背景,对疲劳寿命问题进行深入研究。