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Paying attention to the event of damage of the cylinder of eccentric hydraulic piston pump, the author gave a comment on application of geometric mean treatment method in calculation of elastic loss of stability of thick circular pipe of non-uniform wall thickness and demonstrated thrcugh the calculation of critical pressure of elastic loss of press bar with altered sections that the method results in a evident error and collapse of cylinder of eccentric pump takes place in the external elastic range. An analysis... Paying attention to the event of damage of the cylinder of eccentric hydraulic piston pump, the author gave a comment on application of geometric mean treatment method in calculation of elastic loss of stability of thick circular pipe of non-uniform wall thickness and demonstrated thrcugh the calculation of critical pressure of elastic loss of press bar with altered sections that the method results in a evident error and collapse of cylinder of eccentric pump takes place in the external elastic range. An analysis on technical background of the tests carried by Soviet scientist Yeneminko, theory of linear elasticity of minor bending deflection, choice of deformation curve of thin circular pipe with non-uniform wall thickness and a set of factors that affect accuracy of approximate solutions was described in the paper.The author pointed out that there is a necessity to search theoretically different approximate solutions of elastic loss of stability of circular pipe with non-uniform wall thickness and to carry tests upon elastic loss of stability of circular pipe of non - uniform wall thickness caused by eccentricity of external and internal circles. 评述了在非均匀壁厚圆管的弹性失稳计算中应用“几何平均处理”方法及偏心水力活塞泵筒现场挤毁事例后,认为“几何平均处理”方法的有些做法需要给出证明,并用变截面压杆弹性失稳的临界压力计算说明该方法误差很大;偏心泵筒挤毁是在非弹性范围内发生的。还对原苏联学者耶内敏柯试验的技术背景,小挠度线弹性理论与非均匀壁厚薄壁圆管变形曲线的选择,以及影响近似解精度的几个因素进行了对比分析。最后指出,非均匀壁厚圆管的弹性失稳应在理论上进一步探索不同的近似解,同时也要积极筹备由于内外圆不同心引起的非均匀壁厚薄壁管的弹性失稳的试验工作。 A distributed optic fiber type strain sensing system based on optical time domain reflectometer and used for monitoring large scale structural strain and deformation state is studied in the paper.A new optic fiber minor bend sensor structure used for extracting strain information of various points along the distributed optic fiber is designed.A serial array of optic fiber strain sensor based on the new structure is developed.With the strain measurement of structural components and safety monitoring as... A distributed optic fiber type strain sensing system based on optical time domain reflectometer and used for monitoring large scale structural strain and deformation state is studied in the paper.A new optic fiber minor bend sensor structure used for extracting strain information of various points along the distributed optic fiber is designed.A serial array of optic fiber strain sensor based on the new structure is developed.With the strain measurement of structural components and safety monitoring as main objective,a real-time distributed optic fiber type strain monitoring system is constructed.Some systematic experiments are carried out and good results have been achieved. 研究了一种用于大型工程结构应变、变形状态监测的基于光时域反射技术的分布式光纤应变传感系统。设计了一种新型的光纤微弯传感器结构 ,用于对沿传感光纤分布各测量点的应变信息进行提取 ;在此新结构的基础上 ,研究了全光纤型应变传感器串行阵列 ,以对构件应变测量和安全监测为主要目标 ,建立起了分布光纤应变实时监测系统。进行了系统实验 ,得到了良好的结果。 Ductile iron is the alloy of iron, carbon and silicon, of which carbon is in the form of spherical free graphite. Flaky graphite in gray cast iron leads to brittle fracture of ferrous group by cutting action while spherical graphite in ductile iron avoids such destruction. Ductile iron has the essence of iron, property of steel. As introduced in relevant seismic documents, the damage ratio of centrifugal ductile iron pipe is one-fourth of that of gray cast iron pipe and one-thirtieth of that of other pipe materials.... Ductile iron is the alloy of iron, carbon and silicon, of which carbon is in the form of spherical free graphite. Flaky graphite in gray cast iron leads to brittle fracture of ferrous group by cutting action while spherical graphite in ductile iron avoids such destruction. Ductile iron has the essence of iron, property of steel. As introduced in relevant seismic documents, the damage ratio of centrifugal ductile iron pipe is one-fourth of that of gray cast iron pipe and one-thirtieth of that of other pipe materials. Flexible connection of ductile iron permits easy adjustment of pipeline without pipe fittings in case of minor bending, which makes pipeline adapt to complicated land form. 球墨铸铁是一种铁、碳、硅的合金,其中碳以球状游离石墨存在。在灰铸铁中,片状石墨对铁基质产生“割裂”作用,使之脆裂,而在球墨铸铁中,球状石墨消除了这种破坏作用。球墨铸铁具有铁的本质,钢的性能,据有关的地震资料表明,离心球墨铸铁管在地震中的破损率为灰铁管的1/4,为其它材质管线的1/30。由于球墨铸铁管的接口具有柔性,管线遇到小的弯度时,可以在不使用管件的情况下非常容易地调整。柔性接口的管线可以适应复杂的地形条件。
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