Experimental Investigation on the Dynamics of Pipes Conveying Fluid Based on Strain Gauge Test

Dynamical performance of pipes conveying fluid on board is of great importance to the reliability of machinery.The dynamic equation of a simply supported wet pipe conveying fluid is presented,taking structural damping of the pipe and viscidity of the fluid into consideration.And the equation is also solved by using Galerkin's method.Modal identifications based on strain gauge test are carried out on both dry pipes(without fluid in it) and wet pipes(pipes conveying fluid).It is concluded from the comparison of the results that both natural frequency and the damping ratio decrease as the pipe filled with fluid,but the mode shapes vary little.Variation of equivalent damping factor is also tested.Experimental results reveal that the equivalent damping factor of fluid and the damping ratio depend greatly on the initial deformation,and fluid induced damping decreases the universal damping ratio of the pipes conveying fluid.

Dynamic Strain Field Measurement and Mechanism Analysis of Blasting Descaling of Soot-Delivery Pipe

The dynamic strain field under the action of blasting load is measured by means of a super-dynamic strain system and a CS2092H dynamic measuring analysis system, and the relation between the peak valwe of strain and the quantity of explosive charge is obtained. And the authors probe into the mechanism of soot descaling of soot-delivery pipe under the action of blasting, and offer an effective method to clean soot in soot-delivery pipe. The study provides a theoretical basis for a further study on blasting descaling or soot-delivery pipe.

Ultimate Bending Capacity of Strain Hardening Steel Pipes

Based on Hencky＇s total strain theory of plasticity,ultimate bending capacity of steel pipes can be determined analytically assuming an elastic-linear strain hardening material,the simplified analytical solution is proposed as well.Good agreement is observed when ultimate bending capacities obtained from analytical solutions are compared with experimental results from full-size tests of steel pipes.Parametric study conducted as part of this paper indicates that the strain hardening effect has significant influence on the ultimate bending capacity of steel pipes.It is shown that pipe considering strain hardening yields higher bending capacity than that of pipe assumed as elastic-perfectly plastic material.Thus,the ignorance of strain hardening effect,as commonly assumed in current codes,may underestimate the ultimate bending capacity of steel pipes.The solutions proposed in this paper are applicable in the design of offshore/onshore steel pipes,supports of offshore platforms and other tubular structural steel members.

Elevated temperature strain softening characteristics of 12Cr1MoV steel friction welding pipe joints

The strain softening characteristics analysis of 12Cr1MoV streel friction welding pipe joints.which were removed from heating apparatus pipes ager over 9 and is yearly of service, was undertaken. It is concluded that the evident softening did not occur in the weld metal and HAZ during serice. whereas it did in the base metal 2mm apart from the center of the weld metal. The difference is due to the restriction of the pipe hoop, which is formed on the joint during friction welding. The bainite. microstructure in the weld metal and HA Z, which is harder than the pearlite, pecrostpucture in the base metal, makes contpibution too. ThIS phenomenon is peculiar to the friction weldings pipes.

Strength differential effect and influence of strength criterion on burst pressure of thin-walled pipelines

In the framework of the finite deformation theory, the plastic collapse analysis of thin-walled pipes subjected to the internal pressure is conducted on the basis of the unified strength criterion （USC）. An analytical solution of the burst pressure for pipes with capped ends is derived, which includes the strength differential effect and takes the influence of strength criterion on the burst pressure into account. In addition, a USC- based analytical solution of the burst pressure for end-opened pipes under the internal pressure is obtained. By discussion, it is found that for the end-capped pipes, the influence of different yield criteria and the strength differential effect on the burst pressure are significant, while for the end-opened pipes, the burst pressure is independent of the specific form of the strength criterion and strength difference in tension and compression.

HYDROFORMING OF BIMETALLIC LINED PIPE

A new hydroforming process for manufacturing corrosion-resistant-alloy(CRA)-lined pipe is proposed to overcome the disadvantages in existing technologies, and a new kindof hydraulic expansion device for bimetallic CRA-lined pipe has been researched and developed. Itsoperational principal and technical characteristic is also introduced. The stress and strain in theliner and outer pipe during the hydroforming process have been analyzed and the mechanism ofhydraulic expansion method is studied theoretically. The final forming pressure formula is suggestedand the theoretical analysis is verified by experimental investigation. The results indicate thatthe new technology is feasible and can be applied in industrial production.

Theoretical Assessment of Burst Failure of Internally Pressurized Defect-Free Pipelines with Plastic Anisotropy

In the framework of finite deformation theory, the burst failure analysis of end-opened defect-free pipes with plastic anisotropy under internal pressure is carried out. The analytical solutions of burst pressure and the corresponding equivalent stress and strain are obtained for thin-walled pipes, which can take into account the effects of material plastic anisotropy and strain hardening exponent. The influences of plastic anisotropy on the burst pressure and the corresponding equivalent stress and strain are discussed. It is shown that the burst pressure and the corresponding equivalent stress and strain are dependent upon the plastic anisotropy of material, and the degree of dependence is related to the strain hardening exponent of material. In addition, the effects of the strain hardening exponent on burst failure are investigated.

带扩大桩靴桩基施工挤土效应解析研究

提出新型带扩大桩靴预应力管桩基础.不同于均匀截面管桩的施工挤土效应,由于桩靴尺寸大于预制管桩桩身,桩端扩张不宜视作理想球体而更接近于扁球体(旋转椭球体).基于扁球体扩张源对新型带扩大桩靴桩基施工挤土位移场进行解析求解,基于圆孔扩张理论考虑桩周土塑性区域的体积变形,对扁球体扩张应变路径法计算结果进行修正.通过提出的解析解,研究带扩大桩靴桩基施工挤土效应.结果表明,桩周场地可以根据位移场分布规律,大致分为近地表、近桩端以及桩身附近3个区域.扩张源形态越“扁”,桩身附近区域水平“排开”效应略有增强,近地表区域地面“隆起”位移及近桩端区域竖向位移显著减小,这对于挤土桩施工而言是非常有益的.

一种新型液压导管应变测量装置设计与研究

针对飞行器液压导管应变测量环境复杂,传统有线测量设备传感器布置困难、引线多等问题,提出了一种新型液压导管应变测量方法。该方法基于频响函数法建立测量装置与导管的动力学模型,研究了两者之间的应变映射关系,设计了可拆卸式测量装置,实现传感器非接触测量导管应变;结合理论计算和有限元仿真,研究了测量装置对导管模态及应变的影响,优化了装置设计及相关尺寸参数;通过试验验证有限元仿真结果,检验了装置非接触测量液压导管应变方法的有效性。结果表明,测量装置对导管应变影响微弱,300 Hz以下应变重构相对平均偏差为6.2%,证明测量装置能够有效测得导管应变,该方法和装置有望解决复杂测量环境下飞行器液压导管应变的快速准确测量问题。

非均匀沉降区埋地管道力学响应研究

地层非均匀沉降是埋地管道面临的常见地质灾害之一,影响管道安全运行.为此建立地层沉降区管土耦合模型,研究了地层沉降量、管道壁厚、内压、管材对管道屈曲模式和力学性能的影响.结果表明:地层沉降作用下管道轴向拉伸应变和压缩应变集中在沉降过渡区;沉降量较小时管道表面应变呈波纹状分布,沉降较大时管道产生局部屈曲;相同工况下,薄壁管道易发生屈曲失效,厚壁管道出现波纹状应变分布;随着内压增大,管道屈曲程度逐渐减弱;高钢级管道的屈曲程度越小.

基于蓝牙无线传输技术的液压导管应变测量系统

液压导管应变检测是保证液压系统安全可靠运行和判断系统结构健康状况的关键,针对有线应变测试设备存在的问题,设计了一套基于蓝牙无线传输技术的应变测量系统。系统设计遵循体积小、低功耗的原则,基于蓝牙低功耗、高信号质量的无线传输技术,根据一主多从模式架构设计了主从机电路,设计完成液压导管应变采集和无线通信等功能需求,另外设计配套数据传输与处理软件,在交互界面实现数据实时显示与分析。通过有线采集设备与无线测量系统的应变测量对比实验,证明本文设计的基于蓝牙无线传输技术的应变测量系统能够准确有效测得液压导管应变。

国产B950CF与日本HT100水电用高强钢板成分、组织及力学性能比较

随着水电项目的高落差化、大容量化的发展需要,压力钢管趋于巨型化、厚肉化,为进一步降低制造成本,缩短制造工期,从钢板薄壁化、轻量化、高强韧化、焊接可施工性等角度考虑,1000MPa级水电用高强钢板研发及应用已迫在眉睫。本文详细对比分析了国产B950CF与日本HT100水电用高强钢板的成分特点和组织特征,系统对比了其拉伸、冲击、应变时效性能的差异。结果表明,国产B950CF钢板的各项力学性能水平与日本HT100钢板相当,在板厚方向拉伸性能均匀性、应变时效冲击敏感性优于日本HT100钢板,满足高水头、大容量水电项目压力钢管的设计使用要求。

聚合物增强双金属复合管的弯曲性能分析

为了探究聚合物增强双金属复合管的抗弯性和抗鼓包性能,以规格为φ508 mm×(14.3+3) mm的复合管作为研究对象,通过仿真分析对比机械式复合管和聚合物增强双金属复合管的抗鼓包性能;并通过4点弯曲试验进行了验证。结果表明,模拟与试验结果规律一致,聚合物增强复合管弯曲半径的模拟值与试验值偏差仅为0.4 m,模拟计算结果可靠。试验结果表明,在临界弯曲状态下,聚合物增强复合管的最大应变绝对值是机械式复合管的2.56倍,弯曲半径是机械式复合管的0.39倍;聚合物增强双金属复合管的抗弯能力比机械式复合管更强,性能更优,在海洋石油开发的过程中更具优势。

海上大直径超长钢管桩打桩贯入特性及竖向静载试验分析

针对海上大直径超长钢管桩承载力恢复时间长以及现场试验匮乏等问题,依托浙江省宁波舟山港六横公路大桥项目二期工程,对2.0m直径、113m长钢管桩进行初打和复打高应变测试以及静载测试,研究了大直径钢管桩沉桩贯入特性以及不同休止时间的承载力恢复特性。钢管桩沉桩后承载力存在显著的时间效应,沉桩6天后根据复打检测承载力恢复系数达到1.41,沉桩21天后根据轴向抗压试验承载力恢复系数达到2.22,比单桩设计极限值大22.15%。同时实测发现大直径钢管桩内外泥面高差较小,没有明显的土塞效应。该工程现场试验成果可为类似海上大直径钢管桩设计和施工提供技术参考。

埋深对大直径竹缠绕复合管涵受力性能影响实测与分析

竹缠绕复合材料是我国竹材工业化应用领域的重要原创技术,突破了竹材传统应用的限制,在交通、市政、水利及建筑等多个领域具有广泛应用前景。为推广竹缠绕复合材料在公路工程中的应用,对大直径竹缠绕复合管涵实施现场监测并探究埋深对管涵力学性能的影响具有重要意义。设计了一套针对竹缠绕复合管涵的现场施工监测方法:实现从施工过程到服役期间的土压力、管底沉降、管壁应变全时段连续监测;对1~4 m埋深管涵的受力性能进行分析,探究了埋深对管涵受力性能的影响。试验结果表明:竹缠绕复合管涵属于柔性管涵,管土相互作用随埋深和时间的增加趋于明显,但在较浅埋深下受上部扰动较大;H1~H4最大竖向沉降为33.48 mm,所有管涵工后沉降均满足设计要求;由于管涵材料的变异性与初始缺陷,管顶竖向土压力变化幅度较大,且各埋深管涵管壁变形随时间变化不具有一致性规律;土压力、最大沉降值均随着埋深的增大而增大,除1 m埋深管涵外,随着埋深的增加,管上测点应变有增大趋势,管下测点应变有减小趋势,管涵有较好的适应性变形能力。

逆断层作用下埋地管道屈曲响应分析及预测

地震断层引起的地面永久变形会导致埋地管道屈曲或整体失稳,威胁油气管道的安全。针对跨断层埋地管道屈曲响应的精准预测难题,以断层作用下管道轴向压应变快速增长前的应变作为判断管道局部屈曲的标准,提出了一种跨断层埋地管道屈曲响应仿真分析及预测方法。通过等效边界弹簧对管道端部的轴向补偿,建立了逆断层作用下埋地管道非线性有限元模型,探究了不同敏感参数下管道的应变响应,基于非线性回归得到了管道屈曲预测修正公式,结合实验对比验证了方法的准确性,为管道穿越逆断层的失效分析和安全设计提供了参考。

软土地基处理中PHC管桩桩身及单桩承载力试验研究

为研究软土地基PHC管桩处理效果,结合某泵站工程,通过第三方检测公司对施工单位使用PHC管桩处理后的地基进行抽验。采用低应变反射波法进行PHC管桩桩长、桩身完整性检测,并进行复合地基单桩竖向抗压承载力试验研究,从而判断PHC管桩处理后泵站软土地基中的承载力大小是否满足要求。经第三方抽检,检测结果合格,单桩完整性及复合地检测结果可以直接为本次泵站设计施工及竣工验收提供技术方法和数据借鉴。

地下埋藏式钢岔管设计与水压试验

新疆某在建工程1#岔管为地下埋藏式钢岔管,岔管采用洞内拼装焊接、洞内水压试验的施工方案。岔管位置受附近区域性构造影响,片理及裂隙发育,岩体破碎,开挖过程中通过加强一次支护措施,保证了洞室的稳定和安全。1#岔管承受内水压力较大,最大HD值为2616.0m2,采用800MPa级B780CF钢制作。岔管安装完成后,在洞内进行原位水压试验及应力应变检测,以掌握岔管各重要部位的应力分布及变形情况。1#岔管设计、洞室开挖与支护以及洞内水压试验方案等,对类似工程具有一定的借鉴和指导意义。

基于应变设计X80钢管性能关键影响因素分析及模拟评价

针对基于应变设计管线钢对应变容量的需求,阐述了材料的屈强比、应力比、屈服强度和抗拉强度、均匀延伸率、塑性各向异性等对钢管屈曲应变容量的影响,以及目前在管道材料方面的研究及取得的技术成果。以中石化新疆煤制气外输管道工程为例,对X80M钢级Φ1 219 mm×26.4 mm规格钢管采用数值模拟、性能测试等方法,建立了管道屈曲应变量与力学性能指标的关系式,并采用全尺寸弯曲试验对拟合结果进行了验证,从工程应用角度提出了基于应变设计X80钢管的各项性能指标。结果表明,该项目用管材最小应力比R_(t2.0)/R_(t1.0)为1.033,纵向屈服强度为530~630 MPa,纵向抗拉强度为625~770 MPa,最大屈强比为0.85,最小均匀延伸率为6%。

横州大桥索塔上横梁高支架支撑体系测试分析

大跨度桥梁索塔横梁支架支撑体系测试分析是保障桥梁施工安全的关键手段。横州大桥为主跨400 m的单跨双铰钢箱梁悬索桥,桥塔上横梁采用牛腿支架法施工。文章设计了上横梁施工牛腿高支架支撑体系,开展了施工过程中支架体系受力实测,建立了分步施工有限元模型,并计算、分析了上横梁施工过程中支架支撑体系的结构安全性。结果表明:横梁已浇筑结构在张拉预应力形成刚度后,能够与支架支撑体系共同承载并分担大部分的后期荷载,引起钢管支架各测点在腹板浇筑及后续施工中实测应变发展相对较小;数值模型计算应变结果与实测结果总体吻合良好,可较好地应用于支架支撑体系上横梁分步施工的计算分析;所提出的支架支撑体系能够较好地满足大桥上横梁施工的安全性要求。