Exploration on the Optimization Strategy for the Layup of Composite Material Pressure Vessels Based on Advanced Algorithms

This study aims to explore the influence of the laying angle on the pressure shell structure made of composite materials under the condition of a fixed shape. By using a composite material composed of a mixture of T800 carbon fiber and AG80 epoxy resin to design pressure vessels, this material combination can significantly improve the interlaminar shear strength and heat resistance. The article elaborates on the basic concepts and failure criteria of composite materials, such as the maximum stress criterion, the maximum strain criterion, the Tsai-Hill criterion, etc. With the help of the APDL parametric modeling language, the arc-shaped, parabolic, elliptical, and fitting curve-shaped pressure vessel models are accurately constructed, and the material property settings and mesh division are completed. Subsequently, APDL is used for static analysis, and the genetic algorithm toolbox built into Matlab is combined to carry out optimization calculations to determine the optimal laying angle. The research results show that the equivalent stress corresponding to the optimal laying angle of the arc-shaped pressure vessel is 5.3685e+08 Pa, the elliptical one is 5.1969e+08 Pa, the parabolic one is 5.8692e+08 Pa, and the fitting curve-shaped one is 5.36862e+08 Pa. Among them, the stress distribution of the fitting curve-shaped pressure vessel is relatively more uniform, with a deformation of 0.568E−03 m, a minimum equivalent stress value of 0.261E+09 Pa, a maximum equivalent stress value of 0.537E+09 Pa, and a ratio of 0.48, which conforms to the equivalent stress criterion. In addition, the fitting curve of this model can adapt to various models and has higher practical value. However, the stress distribution of the elliptical and parabolic pressure vessels is uneven, and their applicability is poor. In the future, further exploration can be conducted on the application of the fitting curve model in composite materials to optimize the design of pressure vessels. This study provides important theoretical support and practical guidance for the design of composite material pressure vessels.

Thermo-magnetic analysis of thick-walled spherical pressure vessels made of functionally graded materials

This study presents an analytical solution of thermal and mechanical displacements, strains, and stresses for a thick-walled rotating spherical pressure vessel made of functionally graded materials (FGMs). The pressure vessel is subject to axisymmetric mechanical and thermal loadings within a uniform magnetic field. The material properties of the FGM are considered as the power-law distribution along the thickness. Navier’s equation, which is a second-order ordinary differential equation, is derived from the mechanical equilibrium equation with the consideration of the thermal stresses and the Lorentz force resulting from the magnetic field. The distributions of the displacement, strains, and stresses are determined by the exact solution to Navier’s equation. Numerical results clarify the influence of the thermal loading, magnetic field, non-homogeneity constant, internal pressure, and angular velocity on the magneto-thermo-elastic response of the functionally graded spherical vessel. It is observed that these parameters have remarkable effects on the distributions of radial displacement, radial and circumferential strains, and radial and circumferential stresses.

Melting and Solidification Heat Transfer Characteristics of a Phase-Change Material in a Latent Heat Storage Vessel: Effects of a Perforated Partition Plate and Metal Fiber

Today, latent heat storage technology has advanced to allow reuse of waste heat in the middle-temperature range. This paper describes an approach to develop a latent heat storage system using middle-temperature waste heat (~100oC - 200oC) from factories. Direct contact melting and solidification behavior between a heat-transfer fluid (oil) and a latent heat storage material mixture were observed. The mixture consisted of mannitol and erythritol (Cm = 70 mass %, Ce = 30 mass %) as a phase-change material (PCM). The weight of the PCM was 3.0 kg and the flow rate of the oil, foil, was 1.0, 1.5, or 2.0 kg/min. To decrease the solidified height of the PCM mixture during the solidification process, a perforated partition plate was installed in the PCM region in the heat storage vessel. PCM coated oil droplets were broken by the perforated partition plate, preventing the solidified height of the PCM from increasing. The solidification and melting processes were repeated using metal fiber. It was found that installing the metal fiber was more effective than installing the perforated partition plate to prevent the flow out problem of the PCM.

A comparative study of combustible cartridge case materials

Foamed combustible material based on polymer bonded RDX was fabricated using CO_2 as foaming agent.The inner structures of felted and foamed combustible materials were presented by SEM. The two materials presented different formulations and inner porous structures. The combustion behaviors of felted and foamed materials were investigated by closed vessel test. Simultaneously, the co-combustion behavior of combustible cartridge case with 7-perf consolidated propellants was also investigated. The results of closed vessel test is applicable to gun system which is made of the foamed combustible material as component.

Seismic performance evaluation of water supply pipes installed in a full-scale RC frame structure based on a shaking table test

As an important part of nonstructural components,the seismic response of indoor water supply pipes deserves much attention.This paper presents shaking table test research on water supply pipes installed in a full-scale reinforced concrete(RC)frame structure.Different material pipes and different methods for penetrating the reinforced concrete floors are combined to evaluate the difference in seismic performance.Floor response spectra and pipe acceleration amplification factors based on test data are discussed and compared with code provisions.A seismic fragility study of displacement demand is conducted based on numerical simulation.The acceleration response and displacement response of different combinations are compared.The results show that the combination of different pipe materials and different passing-through methods can cause obvious differences in the seismic response of indoor riser pipes.

Experimental Investigation of the Operating Characteristics of a Pulsating Heat Pipe with Ultra-Pure Water and Micro Encapsulated Phase Change Material Suspension

The specific heat capacity of working fluid is an important influence factor on heat transfer characteristic of the pulsating heat pipe(PHP).Due to the relatively large specific heat capacity of micro encapsulated phase change material(MEPCM) suspension,a heat transfer performance experimental facility of the PHP was established.The heat transfer characteristic with MEPCM suspension of different mass concentrations(0.5% and 1.0%) and ultra-pure water were compared experimentally.It was found that when the PHP uses MEPCM suspension as its working fluid,operating stability is impoverished under lower heating power and the operating stability is better under higher heating power.At the inclination angle of 90°,the temperature at heating side decreases compared to ultra-pure water and the temperature at heating side decreases with the raising of MEPCM suspension mass concentration.The heat transfer characteristic of the PHP is positively correlated with the inclination angle and the 90° is optimum.The unfavorable effect of the inclination angle decreases with heating power increasing.When the inclination angle is 90°,the PHP with MEPCM suspension at 1.0% of mass concentration has the lowest thermal transfer resistance and followed by ultra-pure water and MEPCM suspension at 0.5% of mass concentration has the highest thermal transfer resistance.When the inclination angles are 60° and30°,the effect of gravity on the flow direction is reduced to 86.6% and 50% of that on the inclination angle of 90°,respectively,and the promoting effect of gravity on the working fluid is further weakened as the inclination angle further decreases.Due to the high viscosity of MEPCM suspension,the PHP with ultra-pure water has the lowest heat transfer resistance.When the inclination angles is 60°,the thermal resistance with MEPCM suspension at0.5% of the mass concentration is lower than that at 1.0% at the heating power below 230 W.The thermal resistance of MEPCM suspension tends to be similar for heating power of 230-250 W.At the heating power above 270 W,the thermal resistance with MEPCM suspension at 1.0% of the mass concentration is lower than that at 0.5%.

An Overview of Deepwater Pipeline Laying Technology

The technology and methods involved in pipeline laying in shallow water have evolved to the level of routine and commonplace. However, regarding the unexpected deepwater complexity, the traditional pipeline laying techniques have to confront many new challenges arisen from the increase of the water depth, diameter of the pipe and the welding difficuhy, all of which should be modified and/or innovated based on the existed mature experiences. The purpose of this investigation is to outline the existing and new engineering laying techniques and the associated facilities, which can provide some significant information to the related research. In the context, the latest deepwater pipeline laying technology and pipe laying barges of the renowned companies from Switzerland, Norway, Italy etc., are introduced and the corresponding comparison and discussion are presented as well.

Nonlinear Dynamic Analysis of A Viscoelastic Pipe Conveying Fluid

Incremental harmonic balance method (IHBM) is applied to geometrically nonlinear vibration analysis of a simply supported pipe conveying fluid. the material of which is viscoelastic of the Kelvin- Voigt type. Some unstable phenomena - the appearance of the peak or jumps in the pipe's amplitude frequency curves, which are considered to be of importance to this kind of structure, are presented in the numerical results, and the influence of several parameters of the system on the dynamic characteristic of the pipe are also studied. It is believed that this is the first attempt to search for the periodic solution of the pipe and its intrinsic property with such a method.

Dynamic analysis and regulation of the flexible pipe conveying fluid with a hard-magnetic soft segment

The recently developed hard-magnetic soft(HMS)materials can play a significant role in the actuation and control of medical devices,soft robots,flexible electronics,etc.To regulate the mechanical behaviors of the cantilevered pipe conveying fluid,the present work introduces a segment made of the HMS material located somewhere along the pipe length.Based on the absolute node coordinate formulation(ANCF),the governing equations of the pipe conveying fluid with an HMS segment are derived by the generalized Lagrange equation.By solving the derived equations with numerical methods,the static deformation,linear vibration characteristic,and nonlinear dynamic response of the pipe are analyzed.The result of the static deformation of the pipe shows that when the HMS segment is located in the middle of the pipe,the downstream portion of the pipe centerline will keep a straight shape,providing that the pipe is stable with a relatively low flow velocity.Therefore,it is possible to precisely regulate the ejection direction of the fluid flow by changing the magnetic and fluid parameters.It is also found that the intensity and direction of the external magnetic field greatly affect the stability and dynamic response of the pipe with an HMS segment.In most cases,the magnetic actuation increases the critical flow velocity for the flutter instability of the pipe system and suppresses the vibration amplitude of the pipe.

A novel way for vibration control of FGM fluid-conveying pipes via NiTiNOL-steel wire rope

In this study,a coupling model of fluid-conveying pipes made of functionally graded materials(FGMs)with NiTiNOL-steel(NiTi-ST)for vibration absorption is investigated.The vibration responses of the FGM fluid-conveying pipe with NiTi-ST are studied by the Galerkin truncation method(GTM)and harmonic balance method(HBM).The harmonic balance solutions and the numerical results are consistent.Also,the linearized stability of the structure is determined.The effects of the structure parameters on the absorption performance are also studied.The results show that the NiTi-ST is an effective means of vibration absorption.Furthermore,in studying the effect of the NiTi-ST,a closed detached response(CDR)is first observed.It is noteworthy that the CDR may dramatically change the vibration amplitude and that the parameters of the NiTi-ST may determine the emergence or disappearance of the CDR.This vibration absorption device can be extended to offer more general vibration control in engineering applications.

Evaluate the Possibility of Cracking Pipe on Water Supply Network under the Age of Pipe

Minimizing water loss in water supply networks is one of the objectives for protecting water resources. Currently, the large amount of water loss is mainly due to leakage of the pipeline network. The leaking of pipe can be caused by incorrect construction, impacted by external forces, or corroded pipe material and aging. Therefore, to control and predict the cracking area on pipe, it is necessary to collect data about pipe conditions, approve the solution of technology improvement and define the ability of pipe capacity from setting up to the first preparing time. This paper will demonstrate how to evaluate corrosion pipe under the age of pipe and the impact level of internal pressure pipe at different times, and will put forward solution of effective leaking management on water supply network.

Performance Quality Testing under Combined Loading of Polyethylene Pipes Reinforced with Aramid Fiber

This paper presents the results of the performance quality testing of polyethylene pipes reinforced with aramid fibers, intended for applications such as discharging and gathering oil pipelines, and describes the test rig specifically designed for this purpose. The pipe specimens are submitted to impact with a device that simulates the collision of a pickaxe, and of a backhoe loader. After the impact, the pipes are tested under combined loading comprising internal pressure, and transverse loading; some pipe specimens without previous impact are tested as well. The results show that the reinforced thermoplastic pipes can fully withstand maximal operating pressure levels in the presence of damage and additional transverse loading.

含裂纹油气管道CFRP修复数值研究

裂纹缺陷引发的管道强度下降是埋地油气管道的主要事故原因之一,而高强度、高模量、耐腐蚀的碳纤维增强树脂基复合材料(CFRP)可以很好地缠绕修复缺陷管段。针对有/无CFRP修复20钢含矩形裂纹缺陷管道,采用ANSYS有限元软件模拟内压载荷作用下含裂纹管道修复前后的响应过程,分析了裂纹角度、裂纹长度、裂纹深度、修复长度及修复厚度等参数对含裂纹管道强度的影响规律。研究表明,含裂纹管道的最大Mises等效应力随着裂纹与管道轴向夹角的减小、裂纹长度和深度的增大而增大,内压的增大加剧了缺陷参数对管道强度的影响程度。在工程中要严格控制裂纹在深度和长度方向的扩展,在内部减压后再维修含裂纹管道。CFRP修复厚度是修复后含裂纹管道强度的主要影响因素,随着修复厚度一定程度的增大,含裂纹管道最大Mises等效应力呈线性下降。

交通载荷作用下埋地含缺陷玻璃钢管道力学行为研究

为分析含缺陷玻璃钢管道在交通载荷作用下的力学行为,基于ABAQUS有限元软件建立了含不同形状缺陷管道模型和不同埋深管土模型,研究了不同埋深、不同载荷及缺陷深度对管道不同层中截面沿环向应力分布规律的影响。结果表明,无缺陷管道各层应力分布均匀,含缺陷管道内区域层应力沿管材缠绕方向集中于缺陷对称角处;管道仅含轴向缺陷时管体应力峰值与应力突变幅度最大;缺陷相对深度对管道应力峰值影响较大。

油田用纤维增强塑料压力容器的应用及研究进展

纤维增强塑料压力容器具有耐腐蚀性好、比强度高、耐疲劳性好、质量轻、易于成型、保温性好等优点,近年来逐渐应用于油气处理领域。首先,对纤维增强塑料压力容器在国内油田的应用现状和成型工艺进行了介绍;其次,对影响纤维增强塑料压力容器性能的因素进行了分析总结;然后,对纤维增强塑料压力容器的相关标准进行了介绍,并对国内外纤维增强塑料压力容器无损检测技术的相关研究进行了综述;最后,对纤维增强塑料压力容器在油田的发展趋势进行了展望。

基于微试样的长时服役电厂高温管道力学性能研究

采用小冲孔试验方法、显微硬度试验方法、金相组织分析方法对高温、高压工况下(服役温度为260℃±20℃、工作压力为27 MPa)服役11.5万h后的损伤15CrMo耐热钢管道进行材料研究。小冲孔试验结果表明,与无损伤15CrMo耐热钢管道相比,损伤15CrMo耐热钢管道的小冲孔最大载荷和最大位移下降率分别为5.6%和5.89%。显微硬度分析结果表明,损伤15CrMo耐热钢管道内表面1 mm范围内存在8%的显微硬度升高,这与其内表面经历了长时的高温氧化损伤有关。金相组织分析结果表明,损伤15CrMo耐热钢管道内壁处由于高温氧化腐蚀,存在一定的晶粒脱落,易出现微裂纹,造成管道开裂。综合评价结果为,高温下长时服役对15CrMo耐热钢管道力学性能的损伤程度有限,材料能够保持良好的强度与塑性性能,未发生显著的力学性能退化与脆化,但管道内壁处的高温氧化损伤需引起关注,研究结果可为电厂高温管道的结构完整性评价提供参考。

The Technical Specification and Physical Performance Level of Line Pipes for West-East Gas Pipeline

The west east gas transmission engineering is an important project attracting domestic and foreign attention. The gas pipeline used in this project is a gas pipeline with the longest distance, largest pipe diameter and highest transmission pressure in the history of petroleum pipeline construction of China. For the construction of top rank gas pipeline in the world with high standard, high speed and high benefit, the key of specifying production of metallurgical and pipe making enterprises and ensuring quality performance of the steel and steel pipe is to research and formulate a feasible and satisfactory technical Specification for engineering steel and steel pipe with international level. In this paper the author introduces the establishment of the technical specification for West East gas pipeline project, and lays emphasis on the analysis and discussion of principle and method determining major technical indexes related to line pipes for West East gas pipeline. The author also introduces actual material selection of gas pipeline home and abroad, and presents examination and application of the technical specification for West-East gas pipeline.

多孔材料对泄爆管道LPG爆炸抑制效应的影响研究

为探究多孔材料对泄爆管道液化石油气(LPG)爆炸传播特性的影响特征,采用自主搭建的气体爆炸测试平台,分析不同厚度及孔隙度的碳化硅多孔材料对火焰传播特性和爆炸超压的影响。结果表明:安装多孔材料可有效阻止泄爆管道中LPG爆炸火焰的传播;随着多孔材料孔隙度和厚度的增加,LPG火焰的传播距离、传播速度和强度均减小,其中,材料孔隙度对阻火效果的影响更大;同时多孔材料可降低泄爆管道中LPG的最大爆炸超压,当材料安装位置后端气体未被引燃时,增加多孔材料的孔隙度和厚度,材料前端(PT1、PT2)的最大爆炸超压增大,材料后端(PT3)的最大爆炸超压接近于静态破膜压力。材料孔隙度和厚度的阻火效应表明:在工程应用中,当材料强度达标后,应优先考虑增加材料的孔隙度来进行阻火。

脉动热管太阳能集热器传热性能实验研究

以真空玻璃管为载体、石蜡为相变储热材料、脉动热管和铜管为传热元件,对比分析了充液率φ=50.0%的脉动热管太阳能集热器与铜管太阳能集热器在相同辐照度下的集热性能。研究结果表明,当辐照度大于0 W/m^(2)时,脉动热管太阳能集热器相比于铜管太阳能集热器管壁温度提高了40℃;相较于铜管太阳能集热器,热源温度越高,脉动热管太阳能集热器吸热能力越强,传热效果越好;在相同的辐照度下,相比于铜管太阳能集热器,脉动热管太阳能集热器内的石蜡达到熔点的时间缩短了13%;脉动热管太阳能集热器输出的热量比铜管太阳能集热器高0.5 kJ,随着辐照度的增强,热量差值将会更大;脉动热管蒸发段和冷凝段壁面与其相接触的传热工质会形成一种准平衡态,蒸发段与冷凝段的传热能力呈反比关系,当蒸发段传热能力下降时,冷凝段传热能力上升,保证了集热器的稳定运行。