安全壳再循环地坑滤网应力分析

安全壳再循环地坑滤网是核电厂安全系统的重要设备,再循环工况下它的工作状况直接影响到安全注射系统(应急堆芯冷却系统)、安全壳喷淋系统的正常运行.本文对滤网结构进行在自重和接管载荷下的静态分析、模态分析和地震谱分析.并对结构各使用限制条件下的应力进行组合和评定.结果显示,滤网结构满足ASMEⅢ的规范要求.文章也阐述了结构各方面参数对结构抗震性能的影响.     

螺旋焊线管局部噘嘴应力集中分析

螺旋焊缝局部噘嘴问题是复杂的三维问题，至今没有现成的安全评定公式可以利用，也难以获得纯粹的理论解。应“西气东输”工程之需，本文利用现有直焊缝理论基础，建立了该问题的力学模型，获得了应力集中因子的显式解，给制订螺旋焊线管几保缺陷的安全评定标准提供了理论基础。利用商用有限元工具ABAQUS对螺旋焊线局部噘嘴进行的系统分析显示，本文提供的理论解具有很强的预测能力。     

含凹坑缺陷石油管件塑性极限的分析

在役石油管件安全可靠运行是目前世界各国油气储运业界普遍关注和迫切需要解决的重大课题,而在役石油管件塑性极限强度评价则是为保障在役石油管件安全可靠运行的基础工作。本文对含有椭球形凹坑缺陷石油管件分别在轴向拉力、内压力和轴向拉力与内压力联合作用下的塑性极限强度问题,基于Von.Mises准则和平衡应力场原理,建立管件塑性极限强度理论分析模型,并就具体算例,利用三维弹塑性有限元法,对该模型进行分析比较。结果表明:当凹坑缺陷相对尺寸较小时,此模型可以有效预测含有缺陷管件的塑性极限强度,是一种简便、有效的工程评定方法。     

抽油杆杆体及过渡段的剩余寿命研究

本文通过抽油杆材料疲劳裂纹扩展速率及抽油杆工作载荷的研究，对抽油杆杆体及过渡段存在表面缺陷时的剩余寿命进行了分析、推导、计算，得到了便于工程应用的剩余寿命图线，为抽油杆缺陷评定提供了依据。     

桥梁结构水下基础表观缺陷立体视觉检测试验

针对桥梁结构水下基础表观缺陷检测实际需求,提出立体视觉表观缺陷检测方法。采用SIFT算法完成表观缺陷图像特征提取与匹配,选用MATLAB编译立体视觉表观缺陷检测评定软件,集成桥梁结构水下基础表观缺陷立体视觉检测系统。使用该系统在实验室环境完成水及空气两种环境下混凝土剥落、裂缝及楔槽三种缺陷的检测对比试验,得到每种混凝土试块表观缺陷在不同环境下的检测结果。试验结果表明,立体视觉表观缺陷检测方法能准确评定表观缺陷几何尺寸,从而验证了该方法用于桥梁结构水下基础表观缺陷评定的实用性及可行性。     

X80管道双腐蚀缺陷间相互作用规律研究

为了对腐蚀管道进行准确的安全评价,本文针对X80管道相邻双腐蚀缺陷间的相互作用规律进行了研究。借鉴现有X80管道爆破实验的数据,对数值计算中的单元划分、边界条件设置等进行验证。采用ANSYSWORKBENCH软件对X80管道在腐蚀缺陷下的应力应变状态进行了分析。数值分析结果显示:轴向间距一定时,腐蚀深度越大,轴向相邻双腐蚀间相互作用越明显;当两个相邻腐蚀缺陷轴向距离在3(Dt)1/2以内或环向处于0.07pD以内时,需要考虑两个腐蚀缺陷的相互影响;当两个相邻腐蚀缺陷轴向距离大于3(Dt)1/2或环向间距大于0.07pD时,不需要考虑腐蚀间的相互作用。     

高强度钢船体焊接结构的安全评定

基于欧洲共同体提出的结构完整性评定方法SINTAP,对含缺陷的高强钢船体焊接接头进行安全评定.根据拉伸试验和断裂韧度试验的结果,建立了高强度钢船体焊接结构的二级失效评定曲线.评定结果表明,评定点在曲线范围内,说明该结构是安全的,取代了将焊接接头近似看作均匀材料进行评定的方法,提高了评定精度.     

掺氢天然气管道完整性评价技术的进展与挑战

“双碳目标”背景下,我国积极推进掺氢天然气管道发展,本文总结了国内外掺氢天然气管道完整性评价方面的研究进展与挑战,得到主要结论如下。（1）现有金属材料相容性试验结论不明确,亟需制定国际统一的金属材料掺氢相容性试验标准;掺氢后管材、焊缝性能劣化规律不清晰,需系统地开展相关试验,揭示其氢损伤机理。（2）天然气管道非金属密封材料在氢环境中的密封性能及力学性能尚不明确,亟需开展相关试验以探索其性能规律;工程上缺乏高性能的非金属输氢管道,需研发低渗透耐侵蚀的输氢管材。（3）现有无损检测技术对掺氢后天然气管道的适用性研究不足,需改进或研发更高精度的无损检测工具以满足掺氢条件下对缺陷检测精度的要求。（4）掺氢天然气管道缺陷适用性评价方法研究仍处于初级阶段,需要以丰富的试验数据为基础开展耦合考虑氢介质与应力状态的管材微观损伤本构研究,完善掺氢天然气管道缺陷适用性评价方法。本文可为掺氢天然气管道安全保障相关研究提供参考。     

板背部缺陷的单侧非接触式超声无损检测方法

随着板状结构在石化、航空航天和电力等工业领域中的广泛应用,急需发展相应的无损检测技术,对其结构完整性进行定期评估,以保证结构的安全运行。基于空气耦合换能器的Lamb波技术,可以非接触快速地对板状结构进行扫描,在结构安全检测领域有广阔的应用前景。本文采用基于势函数法的空气耦合板状结构声传播模型,通过理论求解得到其Lamb波临界角随频厚积的变化规律。实验中采取空气耦合换能器激发和接收Lamb波,采用傅里叶变换和信号滤波技术识别S0和A0模式,并通过与理论结果比较进行确认。最后,分别采用S0和A0模式对板背部半通孔缺陷进行定位,结果显示该单侧非接触式超声无损检测方法可用于板状结构背部缺陷的检测。     

基于延性撕裂过程的缺陷评定方法

材料应变硬化、裂纹扩展阻力变化和高应变梯度场均对延性撕裂过程有重要影响。本文提出了一个综合考虑上述因素的缺陷评定方案,并将最后结果整理成工程界易于使用的评定曲线形式。     

Plastic-strain evolution for cyclic loading based on the equations of the field theory of defects

A relation governing the plastic-strain evolution under applied stresses is obtained within the field theory of defects to analyze the specific features of deformation under sign-varying cyclic loading. The effect of the applied stress amplitude, loading frequency, and cycle skewness on the deformation process under uniaxial loading conditions is studied. Specific features of the plastic-strain evolution in a stable deformation process are considered, and the time to failure of the system in an unstable process is determined. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 3, pp. 112–118, May–June, 2006.     

含缺陷粘弹性材料的序参量本构方程

根据缺陷演化期形成的局域温度场的实验成果，用该内部温度场定义缺陷场。然后对统计相关细观缺陷的演化过程结合这些缺陷的生成速率和概率进行分析，认为含缺陷粘弹性材料的动态破坏过程可以用热波传播的程序按通常方法定量描述。     

CONSTITUTIVE EQUATION WITH ORDERED PARAMETERS FOR VISCOELASTIC MATERIAL CONTAINING DEFECTS

Based on the experimental results of local temperature field formed in the evolution pc-riod of defects,the defect field is defined by this internal temperature field.The evolutionary processesof statistically correlative meso-scopic defects are analysed with Ihe growth rate and nucleation rate ofthe meso-defect,and it is deemed that the dynamic failure process of the viscoelastic material with de-fects can be quantitatively described by the normal method of the procedure of heat wave transmission.The defect field is regarded as a complex system of the union of the real sets and null sets,its maincharacteristics depending on the stratum hypothesis about the activities of the subsystems of the higheststratum described by ordered parameters.The fluctuation of ordered parameters is demonstrated bymeans of the projection operator method.The constitutive equation with ordered parameters for themeso-defect evolutionary state of viscoelastic material with defects is deduced from the nonlinear rheo-logical dynamic approach,and its solution is obtained.     

On the lower bounds for critical loads under large deformations in non-linear hyperelastic composites with imperfect interlaminar adhesion

The present paper investigates a mechanism of compressive fracture for heterogeneous incompressible non-linear materials with special kinds of defects of interfacial adhesion under large deformations. The analysis finds the lower bounds for the critical load. In order to calculate the bounds, the problem of the internal instability is considered within the scope of the exact statement based on the application of the model of a piecewise-homogeneous medium and the equations of the 3-D stability theory. The solution of the 3-D problem is found for the most general case accounting for large deformations and the biaxiality of compressive loads. The characteristic determinants are derived for the first four modes, which are more commonly observed. Special attention is given to the calculation of critical loads for hyperelastic layers described by a simplified version of Mooney's potential, namely the neo-Hookean potential.     

Defects in flexoelectric solids

A solid is said to be flexoelectric when it polarizes in proportion to strain gradients. Since strain gradients are large near defects, we expect the flexoelectric effect to be prominent there and decay away at distances much larger than a flexoelectric length scale. Here, we quantify this expectation by computing displacement, stress and polarization fields near defects in flexoelectric solids. For point defects we recover some well known results from strain gradient elasticity and non-local piezoelectric theories, but with different length scales in the final expressions. For edge dislocations we show that the electric potential is a maximum in the vicinity of the dislocation core. We also estimate the polarized line charge density of an edge dislocation in an isotropic flexoelectric solid which is in agreement with some measurements in ice. We perform an asymptotic analysis of the crack tip fields in flexoelectric solids and show that our results share some features from solutions in strain gradient elasticity and piezoelectricity. We also compute the energy release rate for cracks using simple crack face boundary conditions and use them in classical criteria for crack growth to make predictions. Our analysis can serve as a starting point for more sophisticated analytic and computational treatments of defects in flexoelectric solids which are gaining increasing prominence in the field of nanoscience and nanotechnology.     

Stress characterization of elastodynamics with continuously distributed defects

A pure stress formulation of linear nonhomogeneous anisotropic elastodynamics with continuously distributed defects (EcDD) is proposed, and well known solutions of ECDD corresponding to stationary and moving concentrated plastic fields in an infinite body are recovered by direct integration of the stress field equation. A new interpretation of the solutions is given.     

Limit and shakedown analysis of pressurized pipelines containing defects

In this paper, the integrity assessment of pressurized pipelines containing defects is performed by direct simplified methods of limit and shakedown analysis. The defects considered are part-through slots of various geometrical configurations. The engineering situation considered here has practical importance in the pressure vessel and pipe industry. The results are compared with those obtained by a step-by-step procedure using the professional code ABAQUS and where possible, with those provided by semi-empirical formulae used in engineering. The simplified methods are found more economical and more reliable than marching solutions achieved by step-by-step evolutive elastic-plastic analysis. The effects of various part-through slots on the load-carrying capacities of pipelines are investigated. The project was supported by the National Science and Technology Commission of China and by the Department of Structural Engineering, Technical University of Milan, Italy     

铁路路基病害类型、机理及检测与整治技术

针对既有铁路的特点,分析了常见铁路路基病害的类型、机理;提出路基病害的检测应运用现代化检测工具,采用原位和区段测试相结合的方法;针对路基病害整治技术的复杂多样,整治具体路基病害的困难性,指出了铁路路基病害智能管理系统能较好地解决此问题。     

On the relative magnitudes of viscous,elastic and texture stresses in liquid crystalline PBG solutions

The relative contributions of the viscous, elastic, and texture stresses in flows of modestly concentrated liquid crystalline solutions of poly(-benzyl glutamate) or PBG, at low shear rates are assessed by comparing published experimental rheological and light-scattering data to theoretical predictions. The data considered include ratios of Leslie-Ericksen viscosities, the shear viscosity jump at the transition from the isotropic to the liquid-crystalline state, the dependence of the shear viscosity on concentration, and the fraction of slowly relaxing stress after cessation of shearing flow. We quantify the relative contributions of viscous and elastic stresses by estimating from these data a value for the parameter ß^* _{V str} D ^* _r /kT, where _str , is the solvent-polymer friction coefficient and D _r ^* is the rotary diffusivity in the isotropic phase at the concentration where the isotropic phase becomes unstable to liquid crystalline order. The experimental evidence suggests a value \^* _v 0.03, five times lower than the value, 0.15, for dilute solutions. The relative contributions of elastic and texture stresses can be quantified by a parameter in the mesoscopic theory for polydomain nematics; a value of 0.03 gives reasonable agreement with transient shearing experiments, and predicts that the shear viscosity will show an upturn at high polymer concentrations, in agreement with experiments.Dedicated to Prof. Dr. J. Meissner on the occasion of his retirement from the chair of Polymer Physics at the Eidgenössische Technische Hochschule (ETH) Zürich, Switzerland     

裂尖前方塑性区内的局部弹性场

该文给出了平面应变下，不同材料ＨＲＲ场对应的能量分布图，在裂尖前方扇形域内，静水拉应力很高，约为３σ０－７σ０，而等效效应力却很小，接近屈服应力σ０，使此区内仅能产生弹性体变能。