Composite Pipes Research Articles

Bamboo Winding Composite Utility Tunnels: a case study on mechanical behavior with WSN monitoring and numerical simulation

Bamboo Winding Composite Pipes (BWCPs) have many advantages such as good mechanical properties, low cost, low carbon, environmental friendliness, thermal insulation and easy installation et al. At present, BWCP is widely used in urban water supply, drainage, communication cable protection, farmland irrigation etc. It is obvious that the Bamboo Winding Composite materials have good application prospects in the field of utility tunnels. However, considering that the size of utility tunnels is much larger than that of normal pipelines, the wide application of Bamboo Composite Utility Tunnels (BCUTs) is still a challenge. In this paper, the force performance of BCUT in Datong Shanxi Province, was studied using two methods: real time monitoring and numerical simulation. Wireless sensor networks were used for monitoring, and the real time monitoring data of horizontal convergence and strains under the condition of backfill were obtained. The monitoring data indicated that the horizontal convergence can meet the requirement of relevant technical standards. A three-dimensional numerical model of the utility tunnel was established using FEM software. The influence of soil parameters on the deformation and strain of the BCUT was studied using the numerical method. The simulation results were compared with real-time monitoring data. The soil parameters K0 and ksh have significant effects on the deformation, stress and strain of the utility tunnel. This kind of utility tunnel is recommended to use in areas with relatively good geological conditions.

Stability and nonlinear vibration of carbon nanotubes-reinforced composite pipes conveying fluid

This paper focuses on the stability and nonlinear vibration characteristics of carbon nanotubes-reinforced composite pipes conveying fluid, and the mechanism of the combined effects of multiple factors. Based on the assumption of Euler beam and Von-karman nonlinear stress-strain relationship, the dynamic governing equations and generalized boundary conditions of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) pipes are established by Hamiltonian variational principle. Firstly, the modal function suitable for generalized boundary conditions is derived by Galerkin method. The stability of FG-CNTRC pipes system and the relationship between natural frequency and flow velocity are analyzed in this paper. The effect of flow velocity on the natural frequency of pipelines is examined under various carbon nanomaterial distribution patterns and wall thicknesses in this research. Then, the nonlinear vibration characteristics of FG-CNTRC pipes are analyzed by multi-scale method. The method of deducing nonlinear frequency through high-order partial differential equations is also extended in nonlinear analysis. The results show that, in the case of uniform distribution of carbon nanotubes, increasing the wall thickness can improve the stability of the pipe system. The influence of amplitude on the nonlinear frequency is more obvious at the second-order frequency.

Pultrusion molding of continuous fiber reinforced thermoplastic composite pipe using partially-impregnated commingled yarns

Pultrusion molding is one of the high-cycle molding methods for continuous fiber-reinforced plastics using thermoplastic resin, and considering the expansion of industrial applications, shaped parts, such as pipes and L-shapes are more desirable. The following is an example of a product that can be used to achieve this goal. Braided fabrics are one of the most useful preforms for achieving pipe shapes. In this study, commingled yarns and partially impregnated commingled yarns were used as intermediate materials, because excellent impregnation properties and textile workability are required to the fabrication and pultrusion molding of the braided fabrics. However, when forming a pipe shape by pultrusion, the mandrel must be placed in the hollow of the molded product, which causes an increase in pull-out resistance due to shrinkage of the pipe diameter. To solve this problem and achieve high-speed molding of pipe-shaped products by pultrusion molding, this study examined the effects of different intermediate materials and molding conditions on the impregnation state and mechanical properties of molded products, as well as the optimization of the mandrel location. The first part of this study revealed that the impregnation time of partially impregnated commingled yarns is shorter than that of commingled yarns, and as a result, the decrease in void ratio and unimpregnated ratio is smaller, and the decrease in mechanical properties is smaller even if the molding speed is increased. The second part of this study, it was found that the mandrel tip should be positioned so that the temperature of the inner diameter side becomes lower than glass-transition temperature (Tg) during cooling to prevent separating. In addition, it was found that temperature history analysis based on heat conduction calculations is effective in predicting the optimum mandrel position, which varies depending on molding conditions. These results provide a guideline for high-speed pultrusion molding.

Improved extrusion of PP-R and PP-RCT pipes

Plastics processing company Bausano, based in Italy, describes how its new extrusion lines can produce improved PP-R and PP-RCT composite pipes.

Performance assessment of a novel type of Earth-to-Air Heat Exchanger consisting of a composite pipe integrating a convective zone for summer cooling of buildings

Performance assessment of a novel type of Earth-to-Air Heat Exchanger consisting of a composite pipe integrating a convective zone for summer cooling of buildings

Investigating long‐term creep in a composite pipe subjected to transverse loading and aqueous condition

AbstractGlass‐fiber reinforced‐polymer (GFRP) pipes are widely used in various applications under wet conditions. Despite the considerable efforts on characterizing the mechanical response of GFRP pipes from various viewpoints in dry condition, less attention has been given to the influence of moisture absorption on their performance. The main goal of this research is to investigate the influence of moisture absorption on the long‐term creep behavior of GFRP pipes experimentally and theoretically. As experimental program, a GFRP pipe is subjected to a constant compressive transverse loading while it is submerged in water. Thus, the interaction between creep and water absorption are studied up to 5000 h. A systematic modeling procedure is also developed to evaluate the long‐term wet‐creep response of the GFRP pipes. Two scales of micro and macro are linked through an explicit modeling procedure. An excellent agreement is observed between experimental observations and outputs of the developed modeling procedure.Highlights A process is developed to model long‐term creep in composites under wet condition. Long‐term creep is predicted based on short‐term creep behavior of pure resin. Long‐term creep on immersed pipe in water under the transverse loading is simulated. Updating constitutive equations, nonlinear viscoelastic behavior is estimated. The effect of moisture absorption on the long‐term creep behavior is investigated.

IMPACT OF STRUCTURAL DEFECTS ON THE RELIABILITY OF POLYMER PIPES REINFORCED WITH METAL BELTS

Reinforced Thermoplastic Pipes (RTP; or Flexible Composite Pipes) are multilayered pipes that consist of inner, outer polymer shell and reinforcement layers. Although there are different types of reinforcement, due to widespread use in oil gathering systems in Russia, we consider steel strip reinforced pipes in this paper. While developing RTP manufacturers state constructive characteristics after conducting analytical analysis and experimental investigations. Final characteristics values are then published in technical regulations documents. Deviation from these values weaken strength of pipeline.As a result of conducted research it was shown that a thinning of a reinforcement strip by 0,1 mm leads to decrease in a burst pressure by 16 %. Similar effect on the pipe reliability has a deviation of the winding angle.

Effect of Braid Angle on Crushing Performance of Double-Layer Carbon Fiber Composite Pipe

Three-dimensional braided composite materials have the advantages of high specific strength and good specific rigidity, they are widely used in various fields. With the help of the full-scale macrostructure model finite element analysis method to pre-test the mechanical properties of the axial compression, the simulation can observe the failure process, stress distribution and propagation form of the pipe, and study its failure mechanism. Then verify the correctness of the simulation through experiments. The conclusion is that the compressive performance of the material changes with the change in the braid angle. A smaller braiding angle can bear a larger load, but its material failure process is relatively rapid, and the load drop increases as the braiding angle decreases.

ПОТЕНЦІЙНІ ЗАСОБИ ЕКРАНУВАННЯ МАГНІТНОГО ПОЛЯ ПІДЗЕМНИХ СИЛОВИХ КАБЕЛІВ У ПОЛІЕТИЛЕНОВИХ ТРУБАХ З КОМПОЗИЦІЙНОГО МАГНІТНОГО МАТЕРІАЛУ

The magnetic field of the medium- and high-voltage underground power cable line, laid in composite polyethylene pipes having magnetic properties, with the use of special loose-fill/fill-up soil of different dimensions (bulk) is studied by computer modeling. The pipes and additional soils around and near the cables are made of a composite material with effective magnetic properties and can act as a magnetic shield that reduces the level of the field on the ground. The effi-ciency of field shielding depending on the height and width of the composite loose-fill/fill-up soil is analyzed. The exis-tence of the optimal not large (in height) fill-up soil for the best mitigation of the magnetic field on the ground directly above the cables and the influence of the width of the loose-fill/fill-up soils on the shielding efficiency are revealed. The characteristic features of the magnetic field distribution and the field level depending on the availability or non-availability of composite loose-fill soil are presented. The advantages of (trefoil) cable arrangement in one pipe with additional composite loose-fill and fill-up soil are shown. References 30, figures 5.

Абразивная износостойкость и ресурс эксплуатации труб из стеклокомпозита

This article presents studies of the abrasive wear resistance of fiber-glass composite pipes inner surface, which are laid us-ing microtunneling technology under construction of drinking water pipes, irrigation and sewerage systems. Due to a very smooth inner surface, the pipes have a high coefficient of fluid flow speed transmission through the pipe and a low coeffi-cient of roughness. When in long-term operation, the movement of water and solid particles through the pipeline eventually causes wear of inner walls of the pipe. The study of data on abrasive wear and abrasive resistance of fiber-glass composite pipes allows calculating the pipeline's operability under controlled conditions, predicting the period of trouble-free opera-tion of pipelines and making a reasonable choice of material for pipeline manufacturing. The objects of the study of glass composite pipes samples were selected, manufactured by LLC «New Pipe Technologies» using the method of continuous winding with an inner layer based on: orthophthalic polyester, isophthalic polyester and vinyl ester resins. The assessment of the overall wear resistance of the inner surface of the pipes was fulfilled using test equipment according to the Darmstadt method (GOST R 55877-2013, method B). This method allows simulating the abrasion and wear of linings and pipes that may occur in real operating conditions. Crushed quartz was used as an abrasive material. According to the results of the research, the arithmetic mean values of wear and safety coefficients of fiber-glass composite pipes were deter-mined depending on the number of test cycles. The data were used to select the most promising material as a polymer matrix for the production of fiberglass pipes both for water supply and sewerage.

Study on explosive welding of Cu/steel composite pipe under local water environment

AbstractIn order to improve the energy utilization rate and the bond quality of explosive welding, the local water environment method is used in present study. In this paper, several groups of high‐quality Cu/Steel explosive composite pipes are prepared under local water environment. Optical microscope and mechanical property tests are conducted to analyze samples microstructure and mechanical properties. The results show that the waveform dimension of Cu/Steel bonding interface has a positive correlation with explosive layer thickness, and the miniature wavy bonding interface with the highest bonding quality is obtained by using the local water environment method. Compared with the traditional charge method, the consumption of explosives for the local water environment charge method is decreased about 60 % in the same case of experimental conditions. The local water enviroment method solves the problem of ablation damage at the contact surface between metal and explosives, and effectively reduces the diameter expansion phenomenon and end damage caused by boundary effect in the welding process. Through mechanical property tests, it was found that the yield strengths and compressive strengths of Cu/Steel specimens which created by the local water environment method are positively correlated with the explosive thickness.

Study of Copper/Aluminum Bimetallic Tube Rotary Ring Spinning Composite Forming Characteristics

As a plastic forming process developed based on rotary wheel spinning technology, the rotary ring spinning process has the excellent characteristics of high forming accuracy and high material utilization rate, and has been gradually applied to the manufacture of bimetallic composite pipes. In this paper, the forming law of a bimetallic tube in the process of rotary ring spinning was analyzed by numerical simulation and experimentation. The results show that the deformation coordination of the basic and cover tubes increased with the increasing press amount, and the feed ratio had less of an effect on the thickness variation. In addition, the three-way strain of the basic and cover tubes and the degree of influence of the process parameters on the equivalent strain of the tubes were also studied. The results show that the radial strain on both tubes was the largest, followed by the axial strain, and the tangential strain was the smallest; the press amount had the largest effect on the equivalent strain of the tubes, followed by the angle of attack and the feed ratio. These results provide some guidance for the manufacture of high-performance bimetallic composite tubes by rotary ring spinning.

Enhanced ANN Predictive Model for Composite Pipes Subjected to Low-Velocity Impact Loads

This paper presents an enhanced artificial neural network (ANN) to predict the displacement in composite pipes impacted by a drop weight having different velocities. The impact response of fiber-reinforced polymer composite pipes depends on several factors including thickness, stacking sequence, and the number of layers. These factors were investigated in an earlier study using sensitivity analysis, and it was found that they had the most prominent effect on the impact resistance of the composite pipes. In this present study, composite pipes with a diameter of 54 mm are considered to explore the damages induced by low-velocity impact and the influence of these damages on their strength. To evaluate the effect of low-velocity, the pipes were exposed to impacts at different velocities of 1.5, 2, 2.5, and 3 m/s, and preliminary damage was initiated. Next, we used Jaya and E-Jaya algorithms to enhance the ANN algorithm for good training and prediction. The Jaya algorithm has a basic structure and needs only two requirements, namely, population size and terminal condition. Recently, Jaya algorithm has been widely utilized to solve various problems. Due to its single learning technique and limited population information, Jaya algorithm may quickly be trapped in local optima while addressing complicated optimization problems. For better prediction, an enhanced Jaya (E-Jaya) algorithm has been presented to enhance global searchability. In this study, ANN is enhanced based on the influential parameters using E-Jaya to test its effectiveness. The results showed the effectiveness of the E-Jaya algorithm for best training and prediction compared with the original algorithm.

Analysis of bulge failure of steel wire-reinforced thermoplastic composite pipe

A steel wire-reinforced thermoplastic composite pipe (SRTP) was used for water injection connecting line pipe had caused bulge failure of the external surface after 6 years of service. Investigations were performed to identify the most probable causes of the pipe failures. The study was conducted by reviewing the background of the failure, visual physical inspection, test production process analysis, and thermal analysis. The results revealed that the failure of this pipe was mainly caused by scratch defects on the inner surface and the poor resin stability near the cracking site compared to its basal resin. It has scratch defects forming a crack source under the combined action of internal pressure, the resin matrix on the inner surface appears brittle cracking. Subsequently, the medium to be corroded after contacting with the metal wire, losing the pressure bearing effect, and finally forming a bulge on the outer surface under the action of low internal pressure.

On the pressure–deflection relations and instability of carbon-based composite nonlinear pipes

In this paper, for the first time, the nonlinear buckling of curved pipes is investigated for different distributions of single-walled carbon nanotubes (SWCNTs) in the matrix. The curved pipe is subjected to uniformly distributed transverse pressure and experiences uniform temperature rise. Additionally, the pipe is in one-sided contact with an elastic nonlinear medium. Defined thickness-dependent and temperature-dependent material properties of SWCNTs are taken from the results of molecular dynamics (MD) simulations, well-established in the literature on the subject. Five technologically justified types of CNT distributions are considered. Shen’s rule of the mixture is applied to determine the effective properties of CNT-based composites. To avoid determining shear correction factor, the higher-order shear deformation theory is used. The nonlinear components of the Green–Lagrange strain tensor and the principle of virtual displacements are applied to derive the nonlinear system of partial differential equations of motion of the curved pipe. The solution to formulated boundary value problem is obtained by the perturbation technique for both simply-supported and clamped-clamped boundary conditions. The pressure–deflection curves of the curved pipe are obtained and discussed. The investigation of snap-buckling intensity and upper/lower limit load of the curved pipe is presented and new insights for its nonlinear stability are presented. For instance, it is shown that the V-type of CNT distribution profile affects on lower deflection of the curved pipe while the higher deflection exists for the Λ-type profile.

Stress Analysis of ASME Section X Flanges Using Classical Lamination Theory

AbstractThe increased usage of fiber reinforced plastic (FRP) composite pressure vessels and piping components in the past decades in the residential and industrial sectors is attributed to the FRP material resistance to corrosion and chemical attacks. FRP composite flanges are, however, known for their anisotropic behavior. In the ASME code section X, FRP composite flanges are treated using an analytical approach derived from that metallic flanges in addition to the fact that the geometries are made to fit them as much as possible and not designed independently. This is known to have caused structural flaws for certain FRP flange classes and sizes. Using a recently developed anisotropic FRP flange approach, it is proposed to identify the most critical flanges by analyzing the flange parameters such as flange ring rotation and stresses in their different parts; gasket, flange ring, hub, and shell subjected to pressure loading. The study on the strength of flanges described in ASME section X RD-620.1 table, will reveal the most critical size and class flanges and their highly stressed locations. To conduct such a study, the selected flange material is an E glass/Vinyl Ester laminate composite. The study shows that FRP flanges of classes 25 and 50 are most vulnerable and should comparatively be less loaded. The stresses are found to reach 50 MPa in the shell and 58 MPa in the flange ring while the maximum flange rotation is 0.83 deg.

Numerical Analysis of Mechanical Behaviors of Composite Tensile Armored Flexible Risers in Deep-Sea Oil and Gas

As oil and natural gas production continue to go deeper into the ocean, the flexible riser, as a connection to the surface of the marine oil and gas channel, will confront greater problems in its practical application. Composite materials are being considered to replace steel in the unbonded flexible pipe in order to successfully meet the lightweight and high-strength criteria of ultra-deep-water oil and gas production. The carbon-fiber-reinforced material substitutes the steel of the tensile armor layer with a greater strength-to-weight ratio. However, its performance in deep-water environments is less researched. To investigate the mechanical response of a carbon fiber composite flexible riser in the deep sea, this study establishes the ABAQUS quasi-static analysis model to predict the performance of the pipe. Considering the special constitutive relations of composite materials, the tensile stiffness of steel pipe and carbon fiber-reinforced composite flexible pipe are predicted. The results show that the replacement of steel strips with carbon fiber can provide 85.06% tensile stiffness while reducing the weight by 77.7%. Moreover, carbon-fiber-reinforced strips have a lower radial modulus, which may not be sufficient to cause buckling under axial compression, so the instability of the carbon fiber composite armor layer under axial compression is further studied in this paper; furthermore, the characteristics of axial stiffness are analyzed, and the effects of the friction coefficient and hydrostatic pressure are discussed.

Pulmonary and neurological health effects associated with exposure to representative composite manufacturing emissions and corresponding alterations in circulating metabolite profiles.

Cured-in-place pipe (CIPP) technology is increasingly being utilized to repair aging and damaged pipes, however, there are concerns associated with the public health hazards of emissions. CIPP installation involves the manufacture of a new plastic composite pipe at the worksite and includes multiple variable components including resin material, curing methods, and operational conditions. We hypothesize styrene-based composite manufacturing emissions (CMEs) will induce greater pulmonary inflammatory responses and oxidative stress, as well as neurological toxicity compared with nonstyrene CMEs. Further, these CME-toxicological responses will be sex- and time-dependent. To test the hypothesis, representative CMEs were generated using a laboratory curing chamber and characterized using thermal desorption-gas chromatography-mass spectrometry and photoionization detector. Styrene was released during staying, isothermal curing, and cooling phases of the process and peaked during the cooling phase. Male and female C57BL6/J mice were utilized to examine alterations in pulmonary responses and neurotoxicity 1 day and 7 days following exposure to air (controls), nonstyrene-CMEs, or styrene-CMEs. Serum styrene metabolites were increased in mice exposed to styrene-CMEs. Metabolic and lipid profiling revealed alterations related to CIPP emissions that were resin-, time-, and sex-dependent. Exposure to styrene-CMEs resulted in an influx of lymphocytes in both sexes. Expression of inflammatory and oxidative stress markers, including Tnfα, Vcam1, Ccl2, Cxcl2, Il6, Cxcl1, Tgfβ1, Tgmt2, and Hmox1, displayed alterations following exposure to emissions. These changes in pulmonary and neurological markers of toxicity were dependent on resin type, sex, and time. Overall, this study demonstrates resin-specific differences in representative CMEs and alterations in toxicity endpoints, which can potentially inform safer utilization of composite manufacturing processes.

Study on Bearing Capacity of Reinforced Composite Pipe Pile Group in Reclaimed Stratum under Vertical Load

A new stiffened composite pipe pile was developed for improving the foundation of reclaimed ground in ocean engineering. To study the bearing capacity of the stiffened composite pipe pile group, a combination of field test and finite element method was used. Firstly, field tests were performed on the proposed single stiffened composite pipe pile. The single stiffened composite pipe pile model was verified by comparing the numerical simulation results with the field test results. The load transfer mechanism from the stiffened core to the cemented soil and the surrounding soil was clarified. Further, a 3D finite element model of the stiffened composite pipe pile group was established based on the single stiffened composite pipe pile model. Finally, the bearing capacity of the pile group and the stress distribution of each pile were analysed and the influence of the pile spacing on the pile bearing capacity was discussed. The results showed that the axial stress of both the side and corner piles decreased rapidly with an increase in the pile spacing, and the stress-bearing ratio decreased. The stress-bearing ratio of the central pile increases with an increase in pile spacing. The smaller the pile spacing, the larger the load proportion of the composite pile group and the larger the foundation settlement. The optimal design scheme was a composite pile with a 500 mm stiffened core diameter, 700 mm outer cemented soil diameter, and a spacing between piles of four times the cemented soil diameter (2.8 m) considering the group pile bearing capacity and the economic benefits of the project. These results provide a reference for the design and construction of stiffened composite piles for ground improvement projects.

Numerical Simulation of the Pouring Process in Deep-Water Flexible Pipe End Fittings

The pouring quality of epoxy resin in the resin cavity of deep-water composite flexible pipe end fittings has a decisive effect on the performance of the end fitting, and accurate investigation of the resin flow during the pouring process can provide a reference for optimization of the pouring process so that the pouring quality can be improved. In this paper, numerical methods were employed to investigate the pouring process of the resin cavity. The distribution and evolution of defects were studied, and the influence of pouring rate and fluid viscosity on pouring quality was analyzed. In addition, based on the simulation results obtained, some local pouring simulations were conducted for the armor steel wire, the key characteristic structure of the end fitting resin cavity that has a significant influence on the pouring quality, to investigate the influence of the geometrical characteristics of the armor steel wire on the pouring quality. Based on these results, the existing end fitting resin cavity structure and pouring process were optimized, and better pouring quality was obtained.