Sandwich structures with tapered tubes as core:A quasi-static investigation

In this article,the experimental and finite element analysis is utilized to investigate the quasi-static compression features of sandwich constructions built with tapered tubes.3D printing technology was utilized to create the hollow centers of the tapering tubes,with and without corrugations.The results demonstrate that the energy absorption(EA)and specific energy absorption(SEA)of the single corrugated tapered tube sandwich are 51.6% and 19.8% higher,respectively,than those of the conical tube sandwich.Furthermore,the results demonstrate that energy absorbers can benefit from corrugation in order to increase their efficiency.Additionally,the tapered corrugated tubes'resistance to oblique impacts was studied.Compared to a straight tube,the tapered tube is more resistant to oblique loads and has a lower initial peak crushing force(PCF),according to numerical simulations.After conducting a parametric study,it was discovered that the energy absorption performance of the sandwich construction is significantly affected by the amplitude,number of corrugations,and wall thickness.EA and SEA of DTS with corrugation number of 8 increased by 17.4%and 29.6%,respectively,while PCF decreased by 9.2% compared to DTS with corrugation number of 10.

Nonlinear energy chirp compensation with corrugated structures

Herein, a feasible method is proposed to compensate the high-order effect during bunch length compression, thereby enhancing the peak current of a highrepetition-rate X-ray free-electron laser source. In the proposed method, the corrugated structure is inserted downstream of the high-order harmonic cavities to function as a passive linearizer and enhance the longitudinal profile of the electron beam. Three-dimensional simulations are performed to analyze the evolution of the longitudinal phase space, and the results demonstrate that the profile of the electron beam is improved and the peak current can be easily optimized to over 2 kA with a bunch charge of 100 pC.

Thermal-Fluid-Structure Coupling Analysis of Flexible Corrugated Cryogenic Hose

This work presents a numerical investigation of the thermal–fluid–structure coupling behavior of the liquid natural gas(LNG)transported in the flexible corrugated cryogenic hose.A three-dimensional model of the corrugated hose structure composed of multiple layers of different materials is established and coupled with turbulent LNG flow and heat transfer models in the commercial software ANSYS Workbench.The flow transport behavior,heat transfer across the hose layers,and structural response caused by the flow are analyzed.Parametric studies are performed to evaluate the impacts of inlet flow rate and thermal conductivity of insulation material on the temperature and structural stress of the corrugated hose.The study found that,compared with a regular operating condition,higher inlet flow velocities not only suppress the heat gain of the LNG but also lower the flow-induced structural stress.The insulation layer exhibits excellent performance in maintaining the temperature at the fluid–structure interface,showing little temperature change with respect to material thermal conductivity and ambient temperature.The simulation results may contribute to the research and design of the flexible corrugated cryogenic hoses and provide guidance for safer and more efficient field operations.

A Comparative Study of Dispersion Characteristics Determination of a Trapezoidally Corrugated Slow Wave Structure Using Different Techniques

The linear dispersion relation of a trapezoidally corrugated slow wave structure （TCSWS） is analyzed and presented. The size parameters of the TCSWS are chosen in such a way that they operate in the x-band frequency range. The dispersion relation is solved by utilizing the Rayleigh-Fourier method by expressing the radial function in terms of the Fourier series. A highly accurate synthetic technique is also applied to determine the complete dispersion characteristics from experimentally measured resonances （cold test）. Periodic structures resonate at specific frequencies when the terminals are shorted numerical calculation, synthetic technique and cold appropriately. The dispersion characteristics obtained from test are compared, and an excellent agreement is achieved.

Temperature Stress Analysis of Prestressed Concrete Box Girder with Corrugated Steel Webs

To figure out the distribution of temperature gradient along the girder height of steel-concrete composite box girder, combined with the mechanical characteristics of prestressed concrete composed box girder with corrugated steel webs, the calculation formulas of cross-sectional temperature stress along the span in a simply-supported beam bridge with composite section were derived under the conditions of static equilibrium and deformation compatibility of the beam element. The methods of calculating the maximum temperature stress value were discussed when the connectors are assumed rigid or flexible. Theoretical and numerical results indicate that the method proposed shows better precision for the calculation of temperature self-stress in both the top and the bottom surfaces of the box girder. Moreover, the regularity of temperature stress distribution at different locations along the girder span is that the largest axial force of the top or the bottom plate of the box girder is located in the midspan and spreads decreasingly until zero at both supported ends, and that the greatest longitudinal shear density in steel-concrete interface appears at both supported ends and then reduces gradually to zero in the midspan.

HIGH-FREQUENCY VIBRATIONS OF CORRUGATED CYLINDRICAL PIEZOELECTRIC SHELLS

Coupled extensional and flexural cylindrical vibrations of a corrugated cylindrical piezoelectric shell consisting of multiple pieces of circular cylindrical surfaces smoothly connected along their generatrix are studied. To validate the results for the case of relatively thick shells or equivalently high-frequency modes with short wavelengths, existing analysis is extended by considering shear deformation and rotatory inertia. An analytical solution is obtained. Based on the solution, resonant frequencies and mode shapes are calculated.

In-plane dynamics of a fluid-conveying corrugated pipe supported at both ends

The dynamics and stability of fluid-conveying corrugated pipes are investigated. The flow velocity is assumed to harmonically vary along the pipe rather than with time. The dimensionless equation is discretized with the differential quadrature method (DQM). Subsequently, the effects of the mean flow velocity and two key parameters of the corrugated pipe, i.e., the amplitude of the corrugations and the total number of the corrugations, are studied. The results show that the corrugated pipe will lose stability by flutter even if it has been supported at both ends. When the total number of the corrugations is sufficient, this flutter instability occurs at a micro flow velocity. These phenomena are verified via the Runge-Kutta method. The critical flow velocity of divergence is analyzed in detail. Compared with uniform pipes, the critical velocity will be reduced due to the corrugations, thus accelerating the divergence instability. Specifically, the critical flow velocity decreases if the amplitude of the corrugations increases. However, the critical flow velocity cannot be monotonously reduced with the increase in the total number of the corrugations. An extreme point appears, which can be used to realize the parameter optimization of corrugated pipes in practical applications.

波纹钢-混凝土复合结构高温压弯性态研究

波纹钢-混凝土复合结构因其强度较高且施工高效已逐渐应用于隧道支护中,但波纹钢板由于无混凝土的保护,在高温下性能劣化严重。依托云南省普洱市高山寨隧道,利用ABAQUS软件建立有限元模型进行数值模拟分析,研究波纹钢-混凝土复合结构在不同温度和不同偏心距正负弯矩作用下的多工况高温压弯性态。研究结果表明,随着温度的升高,波纹钢-混凝土复合结构中和轴逐渐上移,初始抗弯刚度和极限荷载逐渐下降;当温度>500℃时,结构性能降低幅度最大,宜将500℃作为结构重点关注温度。

窄翼缘异形柱-波纹钢板剪力墙体系的抗震性能

针对钢结构住宅凸梁、凸柱和抗侧刚度不足的问题,提出一种新型窄翼缘异形柱-波纹钢板剪力墙体系;通过与传统H形钢柱-平钢板剪力墙体系进行对比,确定内嵌波纹钢板布置方式,采用ABAQUS软件建立所提出体系的有限元模型,对所提出体系的抗震性能进行分析,探讨外部框架截面形式与布置方式、波纹钢板厚度与剪跨比等对所提出体系的抗侧承载力、耗能能力和塑性变形能力的影响。结果表明:所提出的体系具有较大的抗侧承载力和较强的耗能能力、塑性变形能力,极限抗侧承载力为设计值的1.73倍,具备一定的安全储备;横向布置的波纹钢板能有效减小其作用于框架梁柱的荷载;采用十字形异形柱使所提出的体系有更强的塑性变形能力;所提出体系中的异形柱偏肢宜沿剪力墙面内方向布置,内嵌波纹钢板厚度宜取为3~5 mm,剪跨比宜控制在1.25左右。

CFRP-木结构波纹钢填板螺栓节点力学性能正交试验研究

为了明确异型截面钢填板对节点性能的影响,为木结构异型钢填板螺栓节点提供安全性的设计经验,提出CFRP-木结构波纹钢填板螺栓节点,在正交试验设计条件下开展单轴顺纹拉伸试验研究.试验发现,节点具有多种受力特征,包括木构件剪切破坏、顺纹向张开型断裂(TL断裂)、端部顺纹压溃、CFRP断裂和螺栓弯折等形式;节点在受力过程中没有明显屈服阶段,主要经历线弹性阶段、断裂失效过渡阶段和断裂失效阶段.通过正交参数分析得到不同因素对所提节点主要力学性能的影响程度及规律.结果表明:各因素对极限强度和延性的影响比对弹性刚度的影响显著,且波角和波高为主要影响因素.极限强度与波角负相关且随着波高的增大呈波动变化,延性与波角和波高负相关.

新型零泊松比类蜂窝结构面内非线性刚度研究

几何非线性刚度研究对变形飞行器结构大变形的应用具有重要意义。为研究具有正弦波纹壁的零泊松比类蜂窝结构面内大变形时的非线性力学行为,基于非线性梁理论,考虑几何非线性建立了大变形下的非线性力学模型。利用有限元仿真验证了理论分析方法的正确性,通过参数分析讨论了几何参数对等效应力-应变曲线的影响。结果表明,随着应变的增加,结构的几何非线性造成结构的等效拉伸刚度增大;应力-应变曲线受波纹度、蜂窝角、厚度比的影响较大,受高度比影响不明显。

辽南变质核杂岩主拆离断层的波瓦状构造(corrugation)及其成因

基于对辽南变质核杂岩主拆离断层及下伏韧性剪切带的几何学分析以及拆离断层带构造岩的显微构造研究,结合变质核杂岩构造—岩浆活动及其形成过程和力学机制,重点讨论了主拆离断层的波瓦状构造的特点及其形成条件。结果表明:波瓦状构造的发育与下盘晚期阶段花岗质岩体的侵位具有同时性。伸展构造发育初期就位的深成岩体加热和软化了上部地壳,此时岩石力学属性控制的钝角锯齿状断裂构成了波瓦状构造的雏形,晚期阶段花岗质深成侵入岩的不均匀侵位制约了波瓦状构造的发育。

三明治式飞行器热防护结构研究进展

三明治式先进热防护结构广泛应用于航空航天装备。然而,由于上述结构多为板面与芯体组合形式,加之通道内流场的综合作用,其换热机理呈现出复杂、多变及强耦合的特点,难以针对真实结构及环境工况开展计算、仿真及实验工作。为此,致力于为飞行器热防护结构设计、仿真、试验、优化工作提供可靠技术支撑,本文选取蜂窝夹芯结构、波纹板夹芯结构和点阵夹芯结构,对于点阵夹芯结构又从四面体、金字塔、X型和Kagome型点阵着手,对国际、国内主要研究团队近年来相关流动与换热研究成果进行综述。阐述了3种热防护结构的结构形式和发展历程,分析了板面与芯体组合作用下的换热形式及隔热机理,归纳总结了现有研究不足之处与发展趋势。可以看出,点阵夹芯相比蜂窝与波纹板夹芯结构,由于其芯体内复杂湍流的存在,换热效率高、温度梯度小,具有更好的隔热潜力。

波纹夹层结构增强的新型罐式集装箱及其设计方法

罐式集装箱因安全性高、承载量大、性价比高、运输灵活以及可以实现多种运输方式快速切换等特点,成为液体货物点对点运输的主要装备。近年来,大容量、高承载能力成为罐式集装箱发展的主流方向。提出了一种波纹夹层结构增强的新型矩形罐式集装箱,并建立了新型罐式集装箱罐体结构的理论设计方法。应用该方法设计了承载能力为1 MPa的新型罐式集装箱罐体,并将设计结果与有限元仿真计算结果进行对比。研究结果表明,相较于传统罐式集装箱,新型罐式集装箱的容量效率提升了17.2%;理论设计方法计算的应力分布特征与有限元计算结果一致,最大误差为6.21%,该理论设计方法可以满足工程需要。理论设计方法可以对任意正交各向异性夹层结构增强的新型罐式集装箱罐体进行设计,具有较高的可移植性。

规整填料结构对HD低温蒸发系统中蒸发器性能的影响

为了研究HD低温蒸发系统中波纹板规整填料蒸发器的性能,采用计算流体力学软件FLUENT,对填料通道内废水与空气两相之间逆流接触的流体运动、传质传热过程进行了研究。结果表明:随着波宽的增大,气相出口空气中水蒸气含量先增大后减小,而且气相出口空气温度随着波宽的增大也出现先增加后减小的变化趋势,二者都在波宽为6 mm(宽高比为1.2)时最大;随着波纹倾斜方向与液滴喷淋的夹角增大,气相出口空气中水蒸气含量先增大后减小,气相出口空气温度也出现先增大后减小的变化趋势,其中,在夹角为45°时的填料内部气相出口空气水蒸气含量和空气温度最大,此时填料内部空气与液滴之间传质传热效率最高。由此可得规整填料蒸发器的波纹波宽和波纹夹角对蒸发传质传热的影响都存在1个最佳值,为规整填料的结构参数优化提供了理论依据。

基于X射线的LNG薄膜板残余应力检测与特性分析

该文旨在利用X射线衍射法对MARK Ⅲ型LNG(liquefied natural gas,液化天然气)薄膜板进行残余应力检测,以期获得其残余应力分布规律及典型特性。通过布置16个测点,测试不同方向和区域的残余应力特性。结果显示:大波纹和小波纹交叉节点顶部受压,最大压应力可达178 MPa;板面平直区域呈现压应力,大波纹波峰处受拉,拉应力峰值为115 MPa,小波纹波峰处残余应力受板的边界影响而有所增大。研究工作对于LNG薄膜板的使用、设计和维护具有重要指导意义,可为工程实践提供有益参考,为LNG薄膜板的进一步优化和自主国产化提供重要依据。

横州飞龙大桥主桥设计

横州飞龙大桥主桥为(100+2×185+100)m波形钢腹板连续刚构桥,主梁为单箱单室波形钢腹板组合箱梁,桥面宽13 m,中支点梁高10.9 m,跨中及边跨梁端梁高4 m。腹板采用1800型波形钢腹板,相比传统1600型腹板具有更高的整体屈曲应力;波形钢腹板防屈曲构造采用内衬混凝土和纵、横向加劲肋混合布置的方式,减少了内衬混凝土长度,减轻了结构自重;波形钢腹板与顶板采用长孔型开孔板连接件,与底板采用外包型连接,提高了结合部施工便捷性和耐久性。主梁采用波形钢腹板悬臂自承重施工工法,先边跨后中跨合龙,采用研发的钢架吊篮与智能吊机组合的挂篮形式,提高了施工效率。

接触爆炸下波纹钢⁃混凝土板复合结构水下防爆效果评价

为探究不同波纹钢⁃混凝土板复合结构的水下抗爆防护效果,采用有限元⁃光滑粒子流体动力学耦合算法(FEM⁃SPH)建立水下多介质耦合爆炸模型;设计不同波纹钢⁃混凝土板复合结构防护方案,探究不同复合结构防护层(含3,6,9,12 mm厚波纹钢复合结构、含30°,45°,60°,75°波纹钢复合结构和含10,30,50,70 mm波高波纹钢复合结构)的水下削波吸能效果,并提出耗能分担率对复合结构进行防护效果评价。研究结果表明:混凝土板迎爆面与背爆面的模拟结果与试验结果较为吻合,验证了水下接触爆炸模拟过程;不同复合结构防护方案下,含12 mm厚波纹钢复合结构、含75°波纹钢复合结构和含70 mm波高波纹钢复合结构防护方案较无防护方案测点峰值压力最大降幅为63.2%,60%和57.9%,最大防护率分别为63.2%,60.0%和57.9%,耗能分担率为69.48%,66.26%和63.51%;最优型式(厚度为12 mm/夹角为75°/波高为70 mm)复合结构的削波吸能效果及防护效果均显著优于单一因素影响下的复合结构。研究成果可为不同波纹钢⁃混凝土板复合结构在水下抗爆防护领域的应用提供理论基础。

基于环形试验台的钢轨短波长波磨产生机理研究

介绍一种具有小半径曲线轨道的环形试验台,并对其钢轨表面短波长波磨的形成原因进行分析。环形试验台上车辆运行6 000圈后,在低轨表面观察到钢轨波磨以3.31 mm的波长再现。通过力锤敲击对轨道动态特性进行频率响应函数测试,并在行车条件下对波磨附近处高低轨的振动加速度进行数据采样,采用短时傅里叶变换对采样数据在频域上进行分析。根据试验台的实际尺寸建立轨道三维实体有限元模型,并对其进行模态分析和频响分析。结合试验和仿真的结果分析轨道结构动态特性与钢轨波磨的相关性。结果表明,试验车辆运行速度为12 km/h时,3.3 mm波长波磨的通过频率为1 007 Hz。低轨的1阶垂向Pinned-Pinned频率为2 277 Hz,低轨的1阶横向Pinned-Pinned频率为1 015 Hz,与波磨通过频率相吻合。车辆通过小曲线半径时,低轨上的横向振动幅值远大于高轨上的振动幅值,且低轨上的横向Pinned-Pinned频率1 015 Hz容易被激发,形成与共振频率对应的波磨,且在不同行车速度下低轨被激发出来的横向Pinned-Pinned频率几乎不会受速度的影响,振动幅值随着速度的减小依次降低。低轨频率响应函数试验测试的结果和有限元仿真的结果相吻合,验证了所建立的有限元模型的准确性,且在白噪声的激励下,有限元模型中低轨的横向Pinned-Pinned频率极易被激发出来,其模态振型表现为以钢轨弹性扣件支撑点相对固定。轨道结构波磨的产生主要与轨道结构中高频固有特性相关,钢轨横向Pinned-Pinned模态被激发加剧了钢轨的横向振动是导致小曲线半径低轨钢轨波磨形成的原因。

瓦楞纸板结构特性和工艺改进与应用研究

本文阐述了瓦楞纸板的原纸类型及特点,分析了瓦楞纸板结构特性及对其使用性能的影响,探讨了瓦楞纸板的工艺改进和应用。经分析和探讨可得,瓦楞纸板的形状、楞型和层数是其结构特性的重要参数,在一定程度上决定了瓦楞纸板的性能和用途。在“双碳”和企业降本增效双重目标下,瓦楞纸板生产工艺需改进和进步的空间依然很大。得益于瓦楞纸板质量轻、强度高、绿色环保等优点和近年来学者对瓦楞纸板深入广泛的研究,其应用范围将进一步扩大,高价值产品将进一步被开发。