Composite Overwrap Research Articles

Rational design of semi-interpenetrating network based on hyperbranched polyglycerol grafted MXene/polyurethane–epoxy for compressed hydrogen storage

Hydrogen (H2) energy has emerged as a promising alternative in the automotive sector to replace fossil fuel; however, its storage with volumetric efficiency remains a challenge. The latest type IV storage vessel featuring a polymeric liner with composite overwrap incurs hydrogen saturation, which eventually causes failure. To prevent the H2 dissolution in the liner, we have developed a barrier coating comprised of polyurethane/epoxy semi-interpenetrating network (S-IPN) combined with hyperbranched polyglycerol grafted MXene (h-MXene). The hyperbranched structure facilitated the dispersion of MXene in the coating solution by enhancing the exfoliation and improved the polymer filler interaction by forming covalent and H-bonding through end-terminal hydroxyl groups. Leveraging the dense network of S-IPN combined with the dispersed layer structured h-MXene significantly increased the tortuosity of the spray-coated barrier film applied to the nylon 6 liner. The coating exhibited a 90 % reduction in the H2 gas permeability at only 2 wt% h-MXene concentration, which further improved to above 98 % at 10 wt% loading. Additionally, the h-MXene considerably improved the adhesion with the liner even in a highly stretched condition, signifying the durability of the coating under cyclic pressurization and depressurization of the storage vessel.

Model-experiment comparison of quasi static loading on a composite overwrap pressure vessel (Part 2)

A methodology to develop a 3D Finite Element (FE) model of a full metal-lined Composite Overwrapped Pressure Vessel (COPV) was developed and is presented in this paper. The model is intended for prediction of the metal-composite delamination and residual dent depth developed in the metal liner as a result of quasi-static indentation loading. Cohesive elements are used to model the composite and the metal-composite interfaces. Experimental and numerical comparisons of force–displacement curves, delamination area and residual dent depth are presented. Numerical results are in good agreement to the experimental data.

Processing and structural health monitoring of a composite overwrapped pressure vessel for hydrogen storage

A process and Structural Health Monitoring system was implemented on a Composite Overwrapped Pressure Vessel (COPV) for hydrogen storage at 350 bar to be used in a fuel-cell system of an Unmanned Aerial Vehicle. This work reports the embedment strategy of optical fibre Bragg grating (FBG) sensors to monitor the full life cycle of the vessel, consisting of an aluminium liner and a wound carbon fibre reinforced polymer composite overwrap. A FBG sensing array, bonded on the aluminium liner circumferential section, was covered with a localised unidirectional prepreg composite tape, enabling composite winding and curing monitoring. The sensing array strategy allowed to detect and locate Barely Visible Impact Damage resulting from drop-weight impact tests, based on the ratio of the residual strain amplitude between FBG sensor pairs. Errors as small as 17 mm and up to 56 mm were determined between the predicted and ‘real’ impact locations. To simulate the real-life operational pressure charging and discharging cycles, the COPV was subjected to cycling testing at different pressure ranges. The FBG sensors were able to monitor a total of 20 980 pressure cycles, revealing a linear response to the applied pressure, and remained operational after COPV failure. Furthermore, the FBG sensing array was able to detect the residual plastic strain caused in the aluminium liner by the autofrettage process that the COPV was subjected to prior to pressure cycling, at 600 bar for 2 min, to improve its fatigue performance. This manuscript also reports the COPV structural design by Finite Element Modelling (FEM), its manufacturing process and burst pressure testing for the FEM analysis validation. A small difference of 0.7% was found between the simulated and experimental determined burst pressure of 1061 ± 26 bar.

Manufacturing, burst test and modeling of high pressure thermoplastic composite overwrap pressure vessel

This article presents the design, the prototyping and the burst test of a thermoplastic composite overwrapped pressure vessel. New models for composite stacking in the dome area are proposed and compared to state of the art solution. The complex pattern of tapes following geodesic path around the dome is synthetized in a 2D axisymmetric model. An adapted set of thickness and angle is chosen for each element to correctly model the geometry and the stiffness of the winded composite. A tomography of the whole tank is done to check the geometrical reliability of the model. The behavior of the tank during the burst test is monitored by strain gages to evaluate the stiffness prediction of the built finite element model. A time-dependent behavior is noticed during a pressure plateau at 700Bars. The burst occurs at 1586 Bars in the dome area, where the model predicts the maximum fiber stress.

Environmental Impact Analysis of Oil and Gas Pipe Repair Techniques Using Life Cycle Assessment (LCA)

External corrosion is one of the major defects for oil and gas pipes. Multiple repair techniques are used for repairing such pipes, which have different environmental effects. In this study, the life cycle assessment (LCA) approach has been used to investigate the environmental impacts of four commonly used repair techniques. The techniques are fillet welded patch (FWP), weld buildup (WB), mechanical clamp (MC), and non-metallic composite overwrap (NCO). The repair processes based on guidelines from repair standards are carried out on a defected pipe specimen and experimental data required for LCA are collected. The paper conducts a cradle-to-gate LCA study using SimaPro software. Six environmental impact categories are used for the comparison of repair processes. The results for a repair life of ten years indicate that non-metallic composite overwrap has the highest whereas the fillet welded patch has the lowest environmental impacts.

Development technique of xenon composite over-wrap pressure vessel for electric propulsion system

The quality, reliability and safety of composite over-wrap pressure vessel (COPV) are strongly depended on manufacture process technology level in terms of discreteness of composite structure and winding process. In fact, the present qualification testing, acceptance testing and non-destructive evaluation techniques only can indirectly proof the quality of COPV, and do not presently adequately verify COPV reliability and safety characteristics. It is necessary to analyse various requirements of COPV manufacture process and corresponding influencing factors. There are 24 COPV development requirements which are specified in the ANSI/AIAA S-081A (S-081A) standard. According to the development requirements, the corresponding structure design, manufacture process and quality test solutions are formulated after comprehensive analysis and discussion. This paper introduced the manufacture process variables that affect the quality, reliability and safety of COPV. The COPV, which will be used to electric propulsion system of space system, were developed successfully by the optimized manufacture process technology. The impact-damage protection plan is illustrated in terms of the whole life cycle of COPV, including fabrication, test, transportation, storage and full stage.

Composite overwrap repair of pipelines-reliability based design framework

Considering the ages and need for repairment of the gas and oil transmission pipes in the world, in the past years, lab and field experiments were performed on fiber reinforced polymer (FRP) wrapping to steel pipes. Although this technology has widely been employed for decades, further improvement on the design guidelines is still needed. In this context, this study proposes a reliability structural design framework for the repairment of corroded pipelines using FRP composite wrapping. To be consistent with international structural design standards, reliability-based design framework is to be proposed within a semi-probabilistic approach by calibrating safety factors to account for the associated uncertainties in capacity and load effects to best meet the cost-safety balance in design. Currently, the repair design practice for corroded pipelines is based on a deterministic approach, and it cannot ensure the proper consideration of uncertainties and meeting a consistent level of target reliability in design. This study involves comprehensive experiments of FRP materials under two different environmental conditions for onshore and offshore pipes, which were used to propose the best-fit statistical models to the design parameters to realistically represent the random variables in the proposed safety factor based structural design framework. Through extensive reliability analyses, the values for the safety factors for composite and steel have been proposed according to the target reliability indices and the corrosion rate. The proposed design framework for corroded steel pipes with FRP overwrap repairment is expected to improve the current design practice and optimize the cost and safety by meeting the target reliability level.

Performance of Hydrogen Storage Tanks of Type IV in a Fire: Effect of the State of Charge

The use of hydrogen storage tanks at 100% of nominal working pressure (NWP) is expected only after refuelling. Driving between refuellings is characterised by the state of charge SoC <100%. There is experimental evidence that Type IV tanks tested in a fire at initial pressures below 1/3 NWP, leaked without rupture. This paper aims at understanding this phenomenon. The numerical research has demonstrated that the heat transfer from fire through the composite overwrap at storage pressures below NWP/3 is sufficient to melt the polymer liner. This melting initiates hydrogen microleaks through the composite before it loses the load-bearing ability. The fire-resistance rating (FRR) is defined as the time to rupture in a fire of a tank without or with blocked thermally activated pressure relief device. The dependence of a FRR on the SoC is demonstrated for the tanks with defined material properties and volumes in the range of 36–244 L. A composite wall thickness variation is shown to cause a safety issue by reducing the tank’s FRR and is suggested to be addressed by tank manufacturers and OEMs. The effect of a tank’s burst pressure ratio on the FRR is investigated. Thermal parameters of the composite wall, i.e., decomposition heat and temperatures, are shown in simulations of a tank failure in a fire to play an important role in its FRR.

Performance of hydrogen storage tank with TPRD in an engulfing fire

The performance of a composite hydrogen storage tank with TPRD in an engulfing fire is studied. The non-adiabatic tank blowdown model, including in fire conditions, using the under-expanded jet theory is described. The model input includes thermal parameters of hydrogen and tank materials, heat flux from a fire to the tank, TPRD diameter and TPRD initiation delay time. The unsteady heat transfer from surroundings through the tank wall and liner to hydrogen accounts for the degradation of the composite overwrap resin and melting of the liner. The model is validated against the blowdown experiment and the destructive fire test with a tank without TPRD. The model accurately reproduces experimentally measured hydrogen pressure and temperature dynamics, blowdown time, and tank's fire-resistance rating, i.e. time to tank rupture in a fire without TPRD. The lower limit for TPRD orifice diameter sufficient to prevent the tank rupture in a fire and, at the same time, to reduce the flame length and mitigate the pressure peaking phenomenon in a garage to exclude its destruction, is assessed for different tanks, e.g. it is 0.75 mm for largest studied 244 L, 70 MPa tank. The phenomenon of Type IV tank liner melting for TPRD with lower diameter is revealed and its influence on hydrogen blowdown is assessed. This phenomenon facilitates the blowdown yet requires further detailed experimental validation.

Damage quantification in an aluminium-CFRP composite structure using guided wave wavenumber mapping: Comparison of instantaneous and local wavenumber analyses

Composite-overwrapped pressure vessels (COPV) are increasingly used in the transportation industry due to their high strength to mass ratio. Throughout the years, various designs were developed and found their applications. Currently, there are five designs, which can be subdivided into two main categories - with a load-sharing metal liner and with a non-load-sharing plastic liner. The main damage mechanism defining the lifetime of the first type is fatigue of the metal liner, whereas for the second type it is fatigue of the composite overwrap. Nevertheless, one damage type which may drastically reduce the lifetime of COPV is impact-induced damage. Therefore, this barely visible damage needs to be assessed in a non-destructive way to decide whether the pressure vessel can be further used or has to be put out of service. One of the possible methods is based on ultrasonic waves. In this contribution, both conventional ultrasonic testing (UT) by high-frequency bulk waves and wavenumber mapping by low frequency guided waves are used to evaluate impact damage. Wavenumber mapping techniques are first benchmarked on a simulated aluminium panel then applied to experimental measurements acquired on a delaminated aluminium-CFRP composite plate which corresponds to a structure of COPV with a load-sharing metal liner. The analysis of experimental data obtained from measurements of guided waves propagating in an aluminium-CFRP composite plate with impact-induced damage is performed. All approaches show similar performance in terms of quantification of damage size and depths while being applied to numerical data. The approaches used on the experimental data deliver an accurate estimate of the in-plane size of the large delamination at the aluminium-CFRP interface but only a rough estimate of its depth. Moreover, none of the wavenumber mapping techniques used in the study can quantify every delamination between CFRP plies caused by the impact, which is the case for conventional UT. This may be solved by using higher frequencies (shorter wavelengths) or more advanced signal processing techniques. All in all, it can be concluded that imaging of complex impact damage in fibre-reinforced composites based on wavenumber mapping is not straightforward and stays a challenging task.

Conditionmonitoring of composite overwrap pressure vessels based on buckypaper sensor and MXene sensor

Composite overwrap pressure vessel (COPV) with their excellent specific properties and fatigue resistance are used for high-pressure storage of compressible liquid and gaseous fluids in aerospace industries. To predict the life of COPV or avoid disasters, MXene and buckypaper (BP) sensors are embedded in COPV to manufacture a smart structure that can help COPV to know its strain and pressurization state. Hydrostatic pressure tests are carried out. The changes in resistance measured by MXene and BP sensors are compared. The experimental results show MXene and BP sensors embedded in composite overwrap have the same sensitivity. But BP sensor is more sensitive to the initiation and propagation of microcrack in COPV than MXene sensor. For MXene and BP sensors embedded in the interface between the aluminum liner and composite overwrap, MXene is more sensitive to plastic deformation or compressive residual strains than BP sensor due to the different microstructure of the two kinds of the sensor. In a word, BP sensors are effective for real-time damage Condition monitoring of composite. MXene sensors are more suitable for the performance and structural health condition monitoring of aluminum liner.

Finite Element Analysis of Composite Repair for Damaged Steel Pipeline

Carbon fiber reinforced polymer (CFRP) matrix composite overwrap repair systems have been introduced and accepted as an alternative repair system for steel pipeline. This paper aimed to evaluate the mechanical behavior of damaged steel pipeline with CFRP repair using finite element (FE) analysis. Two different repair strategies, namely wrap repair and patch repair, were considered. The mechanical responses of pipeline with the composite repair system under the maximum allowable operating pressure (MAOP) was analyzed using the validated FE models. The design parameters of the CFRP repair system were analyzed, including patch/wrap size and thickness, defect size, interface bonding, and the material properties of the infill material. The results show that both the stress in the pipe wall and CFRP could be reduced by using a thicker CFRP. With the increase in patch size in the hoop direction, the maximum von Mises stress in the pipe wall generally decreased as the maximum hoop stress in the CFRP increased. The reinforcement of the CFRP repair system could be enhanced by using infill material with a higher elastic modulus. The CFRP patch tended to cause higher interface shear stress than CFRP wrap, but the shear stress could be reduced by using a thicker CFRP. Compared with the fully bonded condition, the frictional interface causes a decrease in hoop stress in the CFRP but an increase in von Mises stress in the steel. The study results indicate the feasibility of composite repair for damaged steel pipeline.

Performance of Nano-Filler Reinforced Composite Overwrap System to Repair Damaged Pipelines Subjected to Quasi-static and Impact Loading

Nano-filler strengthened fiber reinforced polymer-based composite repair systems are recently being used as a promising solution for repair and rehabilitation of transmission pipelines. To increase the efficiency of pipeline repair system using these composites, the present study focuses on characterizing the effect of using nano-silica in glass fiber reinforced polymer (GFRP) composite wrap. Typically, one such widely used pipeline repair system uses 2 layers of Chopped Strand Mat and 4 layers of Woven Roving Mat. In view of this, to assess and characterize the repair system, same configuration of fibers with varying wt.% of nano-silica has been used to fabricate the composite laminates. Tensile, flexure and static indentation tests are performed to determine the mechanical properties of the prepared composites. Ballistic impact test is performed to check the impact energy absorption capability of nano-silica modified GFRP composites. GFRP composites reinforced with nano-silica showed enhanced mechanical behavior as compared to the composites without nano-silica. Upon characterization, the combination of nano-silica reinforced epoxy with best mechanical and impact properties is chosen and is used to repair the defected pipes followed by the pipe pressure testing.

Non-catastrophic perforation of a composite overwrapped pressure vessel

Most spacecraft have a pressurized tank on board, such as a liquid propellant tank or a breathable air supply tank. Because of the serious damage that might result following an on-orbit micro-meteoroid or orbital debris (MMOD) particle impact, a primary design consideration of such (often highly) pressurized tanks is the mitigation of the damage that might occur in the event of such an impact. While catastrophic failure (i.e. rupture) following a high-speed MMOD particle impact would be disastrous, a puncture and the resulting thrust caused by the expulsion of fluids or gas from the perforated tank could result in the de-stabilization of the spacecraft's orbit which could, in turn, also lead to loss of the spacecraft. As such, in the event that catastrophic failure does not occur, risk assessments must still consider whether or not a perforation of a pressurized tank might occur and, in the event of a perforation, what size hole is created by the impact. This paper presents the development of a ballistic limit equation for highly pressurized COPVs that would differentiate between combinations of impact parameters and operating conditions that would result in a hole (without rupture) in the front side of the impacted pressure vessel from those that would not. Empirical models for the hole-out area in the composite overwrap and in the interior liner material in the event of a front side perforation are also developed and discussed.

The use of composite to eliminate the effect of welding on the bending behavior of metallic pipes

In this study, the fiber-reinforced polymeric composite (FRP) overwrap system is proposed to eliminate the effect of the heat-affected zone on the pressure capacity and the deterioration property of the welded pipes. The proposed FRP overwrap system has many advantages. It is cost-effective, and it eliminates the external corrosion while increasing the pressure capacity of the welded pipes. In addition, it also prevents the unplanned shutdown of the pipelines. To evaluate the effectiveness of the proposed FRP overwrapped system, firstly, steel pipe specimens with welded regions were prepared. Secondly, the welded regions were overwrapped with composite material (glass fiber and epoxy resin) using filament winding machine. Finally, the fabricated specimens were tested using three-point and four-point bending tests using the Instron machine. All failure modes of the tested specimens were observed and analyzed using the scanning electron microscopy (SEM). It was proved that the use of the proposed FRP overwrap system had eliminated the effect of the heat-affected zone in welded/steel pipes. The results of three bending tests showed that the maximum flexural load for pipes with two and four welding lines has increased by 16.94 kN and 10.35 kN, respectively. On the other hand, for a four-point bending test, the maximum flexural load has increased by 26.8 kN.

Modeling the effects of loading scenario and thermal expansion coefficient on potential failure of cryo-compressed hydrogen vessels

A multiscale thermomechanical model for a simplified Type-3 cryogenic, compressed-hydrogen (H2) storage vessel is described in this paper. The model accounts for the temperature-dependent elastic-plastic behavior of the vessel's carbon/epoxy composite overwrap and aluminum alloy liner. The homogenized thermo-elastic-plastic behavior for the individual laminae of the vessel layup is obtained using an incremental Eshelby-Mori-Tanaka approach associated with a micromechanical failure criterion to predict laminar failure while a standard elastic-plastic constitutive model is used to describe the behavior of the typical aluminum alloy assumed for the liner. The vessel's response to external loadings is modeled using a finite element method. Four loading scenarios, representing four thermomechanical cycles applied to the vessel, are analyzed to evaluate constituent and laminar stresses as well as the associated failure criterion during the cycle according to these scenarios. The model can provide helpful guidance to mitigate thermal stresses by selecting a suitable loading scenario, optimizing the layup, and tailoring the thermomechanical properties of the resin matrix.

J integral computation and Limit load analysis of bonded composite repair in cracked pipes under pressure

In this paper, an additional criterion was introduced to evaluate the composite repair systems using the limit load analysis. The plastic collapse pressure of API 5L X65 PSL2 steel pressure vessel structure with crack defect is numerically investigated after the structure was been repaired by composite overwrap. The objective of this study was the analysis of the efficiency of composite repair systems using this additional criterion to gain more confidence on it taking into account, the cracks and the overwrap geometries. The material of the pipe is elastic perfectly plastic for the plastic collapse pressure criterion and elastic-plastic using the Romberg Osgood model for fracture mechanic criterion. The additional criterion allows us to compare the uncracked and cracked pipe to estimate the repair efficiency. Moreover, the composite overwrap could restore 90% of the plastic collapse pressure for cracked pipes.

Stress intensity factors analyses for external semi-elliptical crack for repaired gas-pipeline by composite overwrap under pressure

The purpose of this article is to present the stress intensity factors (SIF) solutions for semi-elliptic crack in pipelines under internal pressures, the stress intensity factors are calculated by the three-dimensional finite element method (FEM) for cracked pipelines and repaired pipe by composite patch. The distribution of normalized stress intensity factors (KI, KII and KIII) along the crack front for different crack lengths, crack depth, crack geometry, lap length and composite thickness was obtained by nodal calculations. Our FE results show that the crack frond is non-regular with respect to the rupture mode and presents three zones where the mixed mode (KII) is dominant from the deepest point to the point close to the surface of the pipe not the mode I cited in several studies. When the edge of the crack is close to the outer diameter, the mode III (KIII ) is dominant and this regardless of the state of the pipelines. it can also be noted that the composite repair reduces the SIF KI by 46% and the KII by 55% and the KIII by 72% near the outside diameter of the pipe in each zone of domination. However composite repair is very effective for a rectangular crack as for the semi-elliptical crack. this confirms that the elliptic crack is dominated by the mixed mode II not by mode I.

Design and finite element analysis of metal-elastomer lined composite over wrapped spherical pressure vessel

Over the years, Composite Overwrapped Pressure Vessels (COPV) have been utilized in the aerospace and automotive industries. In the present work, a novel approach has been adopted in designing the liner and test the feasibility of adopted manufacturing and joining techniques. The selection of winding angle and thickness distribution of composite along the meridional direction of the pressure vessel is derived by using an analytical approach based on classical laminate theory. Further, Finite Element Modelling (FEM) software ABAQUS-6.14 is utilized and tested for minimum burst pressure load to account the effects of composite winding angle layup and effective thickness of liner and composite at the pole, dome and equator regions of COPV. Among the various failure criterion of COPV, liner buckling and bond failure between the liner and composite overwrap resulting in the creation of the debond region are considered. These failures are concerned with contact issues and can be minimised by proposing to include a hyperelastic elastomer layer between the liner and composite overwrap. The analytical and FE analysis approach towards predicting the strength response of composite under applied load showed good agreement. At minimum burst pressure load findings showed that overall behaviour, stress-strain distributions and effect of elastomer thickness on liner were found satisfactory. A critical study involving Finite Element Analysis (FEA) based liner alone burst pressure test, and credibility of joining techniques employed in assembly of liner is analysed and found acceptable.

Evaluation of the mechanical performance of a composite multi-cell tank for cryogenic storage: Part I - Tank pressure window based on progressive failure analysis

Understanding of the thermal and mechanical behaviour of conformal tanks when utilized in cryogenic fuel storage is considered crucial in the hypersonic aircraft sector. This behaviour is strongly dependent on the way the tank itself is designed. This study focuses on the effect of design on the performance of an innovative Type IV multi-spherical composite-overwrapped pressure vessel at both ambient and cryogenic conditions. A method to evaluate the required number of reinforcement rings at the intersections and thus avoid damage in those regions under pressurization is outlined. A thermo-mechanical FE-based model coupled with a progressive failure analysis (PFA) algorithm enables to evaluate the pressure window of the multi-sphere at ambient conditions. Additionally, a transient analysis -included in this study-is used to determine the different heat transfer mechanisms, temperature and strain evolution at the tank wall throughout cryogenic operation (chill-down, pressure cycling and purging). The temperature dependency of the tank wall materials is obtained by coupon testing and fitting functions and is hereby incorporated in the analysis. The most important outcome here is the absence of damage in the composite overwrap at cryogenic environments; this may be considered as a positive indication about the suitability of the Type IV multi-spherical COPVs for cryogenic storage.