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11.
用A2参数描述裂纹尖端约束效应,考虑裂纹尖端约束水平对断裂阻力的影响,对R6失效评定曲线进行修正。以X80钢为例,根据不同约束水平试件测试得到的JR–△a曲线,给出了与裂纹尖端约束相关的失效评定曲线。在使用有限元对带裂纹内压管道进行弹塑性分析的基础上,利用失效评定曲线对失效载荷进行预测;与试验结果比较表明:采用约束修正失效评定曲线,在对存在缺陷的构件进行安全性评定、寿命评估、失效概率计算时,考虑约束效应对断裂韧度的影响可以更充分地发挥构件的强度潜力。 相似文献
12.
Mechanical arrestors are frequently used in gas transmission pipelines to prevent the possibility of long running cracks. These arrestors have the effect of reducing the pipe from opening as the crack passes. This decreases the available crack driving force and, as a result, crack arrest may take place. This essentially is a second line of defence against catastrophic failure in the event crack initiation cannot always be prevented. A novel analyzing method presented in this paper has been developed to investigate the suitability of these crack arrestors. This is based on a fluid/structure/fracture interaction package, PFRAC. A dynamic finite element approach has been developed for a three dimension curved beam with initial plane curvature, which has been implemented in PFRAC to simulate the behaviour of the arrestor. The contact conditions between the pipe wall and the arrestor, along with the various computational procedures, are described. Several numerical results for a cracked pipe with arrestors are presented and compared with those for pipes without arrestors. 相似文献
13.
M.S. Arney R. Bai E. Guevara D.D. Joseph K. Liu 《International Journal of Multiphase Flow》1993,19(6):1061-1076
Results from new experiments on the lubricated pipelining of emulsified waxy crude oil and No. 6 fuel oil are presented and compared with other sources of literature. A correlation formula which estimates the holdup fraction is introduced and evaluated for all available experimental data. A simple theory is given which is based on the concentric core-annular flow model and leads to a Reynolds number and friction factor which reduce a large body of experimental data onto one curve; with the best results in the high Reynolds number flow regime. 相似文献
14.
15.
城市燃气管道是城市基础设施的重要组成部分,由于城市路面车流量的增加、道路的路况以及管道本身材质的缺陷,在长期的工作环境下,埋入地下的管道受到了各种力的作用,其受力情况十分复杂。目前管道的埋深和管道本身的设计是根据设计人员的经验或者简单理论分析来确定的,遇到沉降因素复杂的特殊地段管道,其安全就不能保证,所以有必要进行实验分析。本文通过特殊地段管道的模拟试验,分析了在不同沉降因素作用下管道的安全性,试验中应用光纤检测系统及电测系统同时进行检测,两者的分析结果相近,为燃气管道沉降参数监测与预报系统的建立奠定实验基础。 相似文献
16.
ChenGang LiuYinghua XuBingye 《Acta Mechanica Solida Sinica》2003,16(2):102-109
The integrity assessment of defective pipelines represents a practically important task of structural analysis and design in various technological areas, such as oil and gas industry, power plant engineering and chemical factories. An iterative algorithm is presented for the kinematic limit analysis of 3-D rigid-perfectly plastic bodies. A numerical path scheme for radial loading is adopted to deal with complex multi-loading systems. The numerical procedure has been applied to carry out the plastic collapse analysis of pipelines with part-through slot under internal pressure, bending moment and axial force. The effects of various shapes and sizes of part-through slots on the collapse loads of pipelines are systematically investigated and evaluated. Some typical failure modes corresponding to different configurations of slots and loading forms are studied. 相似文献
17.
Analysis model to simulate the cracked pipe buried in soil 总被引:1,自引:0,他引:1
This paper describes the use of the finite element method to simulate crack propagation in a pipeline in the presence of soil
backfill. Since typical values for soil modulus are known, a spring element can be used to simulate the effects of backfilled
soil on crack propagation. This consists of the relationship between the soil property and the stiffness of the spring element,
and the effect of backfill depth on the crack propagation in the pipes. By equating crack driving force,G, in the presence of soil, to the dynamic fracture toughness of the pipeline material, a theoretical predictive capability
is obtained for the first time for the gas transmission and distribution pipelines. Numerical calculations have also been
carried out for the cracked pipe with backfill and without backfill. 相似文献
18.
对腐蚀管道的模糊可靠度计算方法进行了深入研究,提出了确定性可靠度和模糊可靠度两个基本概念;提出了基于断裂失效判据、基于FAD失效评估图和基于剩余强度3种方法计算模糊可靠度的方法;提出了3种新的方法计算确定性可靠度,即改进的JC法、GA—JC法和改进的Monte-Carlo法.以胜利油田某试验区已加入缓蚀剂的注水管道为例,采用本文建立的计算模糊可靠度的3种计算方法和确定性可靠度的3种方法,分别计算注水管道可靠度随着时间的变化趋势.在模糊可靠度的3种计算方法中,基于剩余强度失效方法比较适中,是计算模糊可靠度较好的方法;在确定性可靠度的3种计算方法中,改进的Monte-Carlo法较好. 相似文献
19.
V. A. Rukavishnikov O. P. Tkachenko 《Journal of Applied Mechanics and Technical Physics》2003,44(4):571-583
Slow motion of a pipeline modeled by a bent rod in a viscous medium is studied. It is assumed that the displacements of the axial line of the rod are finite and its strains are small. The mutual influence of the tensile axial force and transverse deflections is taken into account. Equations of motion are derived and some numerical examples are considered. An approximate estimate of stresses in the pipeline wall is given. 相似文献
20.
本文对直径为100mm带套筒构件埋地燃气管道绝缘接头的强度进行了计算和实验分析研究.计算研究中根据在符合实际工程下确定带套筒构件埋地燃气管道绝缘接头密封部位的应力和位移,以及对管道密封性能的影响;实验研究中根据对直径为100mm带套筒构件埋地燃气管道绝缘接头进行符合实际工况的试验,测量绝缘接头密封部位的应力和位移,以及密封圈的受损程度.对计算和实验结果进行分析比较,确定带套筒构件埋地燃气管道绝缘接头在装配中的最小预紧力,分析在不同因素作用下管道绝缘接头的安全性,并为其它直径类型带套管构件埋地燃气管道绝缘接头的设计提供可靠的依据. 相似文献