Composite Vessels Research Articles

필라멘트 와인딩 복합재 압력용기의 저속충격손상 평가에 관한 연구

This paper presents the impact damage behavior of filament wound composite vessels and the effect of surface protective materials on their impact resistance. Using an instrumented impact testing machine, a series of impact tests was performed on the base panels and the protected panels (panels with surface protective materials of rubber, kevlar/epoxy or glass/epoxy laminates) that were cut from the full scale vessel. And the impact damage parameters were used to identify the effect of protective materials on the damage resistance of composite vessels. Damage resistance of the composite vessels was considerably affected by the protective materials regardless of the shape of the indenters. Among the protective materials, glass/epoxy laminates was the most effective mean for improving the damage resistance of composite vessels.

Nonlinear finite element analysis of mechanical characteristics on CFRP composite pressure vessels

CFRP(Carbon Fibre Reinforced Plastic) composite pressure vessel was calculated using finite element program of ANSYS for their mechanical characteristics in this paper. The elastic-plastic model and elements of Solid95 were selected for aluminium alloys of gas cylinder. Also liner-elastic model and layer elements of Shell99 were adopted for carbon fibre/epoxy resin. The stress state of CFRP composite pressure vessel was calculated under different internal pressures include pre-stressing pressures, working pressures, test hydraulic pressures, minimum destructive pressures etcetera to determine the size of gas cylinder and layer parameter of carbon fibre. The mechanical characteristics CFRP composite vessel could were using to design and test of gas cylinder. Numerical results showed that finite element model and calculating method were efficient for study of CFRP gas cylinder and useful for engineering design.

Strength reliability analysis of aluminium–carbon fiber/epoxy composite laminates

Strength reliability of composite laminated structures relates to a series of parameters such as the design sizes, material parameters and load level. By introducing the Monte Carlo simulation and response surface method respectively, a static strength-based reliability model is proposed to predict the reliability of aluminium–carbon fiber/epoxy composite laminates for composite vessels. The burst pressure of composite vessels for different layer structures is predicted using finite element analysis. In the reliability analysis, two design parameters for composite vessels: the radius of polar axis and the winding thickness of each composite layer at the cylinder are assumed to obey the uniform distribution and Gaussian distribution respectively, and the burst pressure of composite vessels is taken as the random output response. Effects of the number of sampling and the limit strength on the strength reliability of composite vessels are explored. Besides, the numerical results obtained using two methods and two distributions for two random input parameters are compared in terms of the calculation efficiency and accuracy. Numerical results also indicate the proposed probability method exhibits preferable advantage over the conventional design method merely using empirical safety coefficient.

Autofrettage of layered and functionally graded metal–ceramic composite vessels

The residual compressive stresses induced by the autofrettage process in a metal vessel are limited by metal plasticity. Here we showed that the autofrettage of layered metal–ceramic composite vessels leads to considerably higher residual compressive stresses compared to the counterpart metal vessel. To calculate the residual stresses in a composite vessel, an extension of the Variable Material Properties (X-VMP) method for materials with varying elastic and plastic properties was employed. We also investigated the autofrettage of composite vessels made of functionally graded material (FGM). The significant advantage of this configuration is in avoiding the negative effects of abrupt changes in material properties in a layered vessel – and thus, inherently, in the stress and strain distributions induced by the autofrettage process. A parametric study was carried out to obtain near-optimized distribution of ceramic particles through the vessel thickness that results in maximum residual stresses in an autofrettaged functionally graded composite vessel. Selected finite element results were also presented to establish the validity of the X-VMP method.

Obtaining an Optimum Weight for a Composite Pressure Vessel

Weight of a composite cylindrical pressure vessel is an important issue investigated here. Design variables include number of layers and thickness, ply angle, volume fraction, and material properties in each layer. The constraint is based on Hoffman criterion and the optimization technique is a messy genetic algorithm (mGA). It is shown that with multilayered structure, we can have a vessel with a weight less than half of that for a single layered composite vessel under a given internal pressure.

Experimental and numerical studies on the bonfire test of high-pressure hydrogen storage vessels

Abstact The bonfire test is an important prototype test in the standard of hydrogen storage vessels. It is designed to demonstrate the safety performance of the vessel and the Pressure Relief Devices (PRD) under a specified fire condition. However, the required temperature of the thermocouples, which is one of the most relevant parameters, is still not unified. The fuel types and fuel flow, which may influence on the temperature distribution and the PRD activation time, are also not specified in the standards. In this paper, an experiment was carried out on a composite vessel filled with hydrogen and the experimental results of temperature and pressure were obtained. A 3D simulation model was developed to study the bonfire test. The effects of fuel type, fuel flow and filling medium on the temperature rising of internal gas were studied. It reveals that the influence of fuel type on the temperature rising is significant. In addition, the rate of temperature rising increases as the fuel flow increases. However, the filling medium has little effect on the temperature rising.

PS20 CFRP製FW容器の損傷進展解析に関する研究(フェロー賞対象ポスターセッション)

Composite vessels are used as a substitute for metal vessels in high pressure fuel tank and oxygen tank, because composite vessel is smaller and lighter than metal one of equal performance. They have many design parameters, for example, stacking sequence, layer thicknesses, nding orientations, etc. However, these parameters are not made full use of, because experimental evaluation of pressure vessels requires much time and cost Therefore, numerical evaluation in design can reduce time and cost, and enhance pressure tightness. In this study, we propose a numerical method to analyze the mechanical behaviors of filament-wound vessels. In the proposed method, filament angles at both cylindrical and dome section have been considered, and the development of damage has been estimated by 3D FEM based on damage mechanics. Damage of F'RP was evaluated by Hoffman criterion for composite materials. The numerical results show that the initial damage occurs at the dome section near the end cap, and the mode of damage is transverse creck. In addition, the results show that not only winding angles but also tanic non-uniform deformation is important factor for the final strength.

521 面外負荷を受けるCFRP複合圧力容器の損傷挙動に及ぼす自緊処理の影響(高分子/高分子基複合材料(1),ものづくりにおける基礎研究と先端技術の融合)

521 面外負荷を受けるCFRP複合圧力容器の損傷挙動に及ぼす自緊処理の影響(高分子/高分子基複合材料(1),ものづくりにおける基礎研究と先端技術の融合)

Delivery of cold hydrogen in glass fiber composite pressure vessels

We are proposing to minimize hydrogen delivery cost through utilization of glass fiber tube trailers at 200 K and 70 MPa to produce a synergistic combination of container characteristics with properties of hydrogen gas: (1) hydrogen cooled to 200 K is ∼35% more compact for a small increase in theoretical storage energy (exergy); and (2) these cold temperatures (200 K) strengthen glass fibers by as much as 50%, expanding trailer capacity without the use of much more costly carbon fiber composite vessels. Analyses based on US Department of Energy H2A cost and efficiency parameters and economic methodology indicate the potential for hydrogen delivery costs below $1/kg H 2. Dispensing cold hydrogen may also allow rapid refueling without overtemperatures and overpressures which are typically as high as 25%, simplifying automotive vessel design and improving safety while potentially reducing vessel weight and cost. Based on these results, we suggest hydrogen delivery by truck with trailers carrying hydrogen gas at pressures as high as 70 MPa, cooled to approximately 200 K in glass fiber vessels.

Optimal design of high pressure hydrogen storage vessel using an adaptive genetic algorithm

The weight minimum optimization of composite hydrogen storage vessel under the burst pressure constraint is considered. An adaptive genetic algorithm is proposed to perform the optimal design of composite vessels. The proposed optimization algorithm considers the adaptive probabilities of crossover and mutation which change with the fitness values of individuals and proposes a penalty function to deal with the burst pressure constraint. The winding thickness and angles of composite layers are chosen as the design variables. Effects of the population size and the number of generations on the optimal results are explored. The results using the adaptive genetic algorithm are also compared with those using the simple genetic algorithm and the Monte Carlo optimization method.

Structural Response Optimization of a Light-Weight Composite Blast Containment Vessel

This paper proposes an optimization technique for increasing the structural integrity of a light-weight composite blast containment vessel. The vessel is cylindrical with two hemispherical ends. It has a steel liner that is internally reinforced with throttles and gusset plates and wrapped with a basalt-plastic composite. A computationally-efficient finite element model of the blast containment vessel was proposed and verified in an earlier work. The parameters of the vessel are incorporated within an iterative optimization procedure to decrease the peak strains within the vessel, which are caused by internal blast loading due to an explosive charge placed at the center of the vessel. The results of the proposed procedure are validated for different initial guesses of the design variables.

Finite element analysis of burst pressure of composite hydrogen storage vessels

Carbon fiber/epoxy composites have been increasingly used to develop the lightweight high pressure hydrogen storage vessel in areas of the hydrogen fuel cell vehicle. In this research, a 3D parametric finite element model is proposed to predict the damage evolution and failure strength of the composite hydrogen storage vessels, in which a solution algorithm is proposed to investigate the progressive damage and failure properties of composite structures with increasing internal pressure. The maximum stress, Hoffman, Tsai–Hill and Tsai–Wu failure criteria which are employed respectively to determine the failure properties of composite vessels are incorporated into the numerical method as individual subroutines. The birth-to-death element technique in the finite element analysis is used to describe the mechanical properties of carbon fiber/epoxy composite elements. Parametric studies in terms of the effects of different failure criteria are performed and the calculated failure strengths of composite vessels are also compared with the experimental results.

Finite Element Modelling of Thermoplastic Matrix Composite Gas Cylinders

Continuous glass/polypropylene (GF/PP) commingled fiber tapes were employed to produce wrapped pressure gas vessels for domestic applications by using filament winding. The vessel structural-wall was built using a hybrid solution consisting in a very thin steel liner over wrapped by the filament wounded GF/PP commingled fiber tape layers. FEM analysis was used to evaluate if the composite gas pressure vessel based on the hybrid solution (steel liner + glass fiber reinforced thermoplastic) is capable to withstand the following pressure requirements: the metallic liner, alone, a minimum burst pressure of 4MPa and whole hybrid composite vessel minima internal test and burst pressures of 3 MPa and 6.75 MPa, respectively. Finally, gas pressure vessel prototypes manufactured in industrial cycle conditions were submitted to burst pressure tests to prove that they accomplish all European standard strength requirements.

A Rete Mirabile of the Posterior Cerebral Artery

We present the case of a 41-year-old man with a vascular network associated with the left posterior cerebral artery (PCA). Although initially considered to be a brain AVM, further investigation showed no arteriovenous shunting and a rete mirabile of the PCA was diagnosed. A well known but rare occurrence mainly in the anterior circulation, rete mirabile has not previously been described in the PCA.The PCA is a composite vessel, developmentally. Its proximal portion derives from the posterior division of the ICA while its cortical territories are annexed from the anterior choroidal artery adjacent to the lateral geniculate body. We propose that this rete (or network) represents a persistence of the embryonic anastomosis betweenthe AChA and the PCA.

Calcium Channel Blockers and Angiotensin-Converting Enzyme Inhibitors May Be Associated with Altered Atherosclerotic Plaque Size and Morphology

Correlations of atherosclerotic plaque attributes with clinical presentation have not been studied in peripheral arterial disease (PAD). The aim of the current study was to identify clinical variables associated with alterations in PAD plaque morphology. Thirty-one patients underwent intravascular ultrasonography (IVUS) at the time of arteriography for symptomatic PAD. IVUS data were analyzed with radiofrequency techniques for quantification of plaque composition, plaque volume, and total vessel volume. Associations between plaque characteristics and clinical variables were evaluated. Univariable and multivariable analyses were performed using t-test, Pearson correlations, F-tests, and analysis of variance. Calcium (Ca2+) channel blocker use was associated with a smaller total atherosclerotic plaque burden (44.2 +/- 2.7 vs 52.9 +/- 2.5%; p < .05), and decreased fibrous plaque content (18.2 +/- 1.8% vs 24.0 +/- 1.9%; p < .05). Angiotensin-converting enzyme (ACE) inhibitor use, however, was associated with a larger total atherosclerotic plaque burden (58.3 +/- 2.2% vs 42.9 +/- 2.1%; p < .01) and larger fibrous plaque content (27.2 +/- 2.0% vs 17.7 +/- 1.6%; p < .001). Multivariable analysis was performed to evaluate which factors may differentially impact the response variable measurements of plaque volume to vessel volume. Based on this model, those without the use of an antihyperlipidemic agent or ACE inhibitor had an average total atherosclerotic plaque burden of 47.7%. Those on an antihyperlipidemic agent had an average decrease of 7.0% (p < .05), whereas those on ACE inhibitors had an average increase of 16.2% from the baseline value (p < .001). The use of calcium channel blockers is associated with significantly decreased atherosclerotic plaque burden and decreased fibrous plaque content, whereas the use of ACE inhibitors was associated with an increase in plaque burden and an increased fibrous plaque content. The use of these medications in PAD may alter plaque morphology with the potential to affect clinical outcomes.

Finite Element Modeling of a Lightweight Composite Blast Containment Vessel

This paper presents various approaches for finite element modeling of a cylindrical lightweight composite vessel for blast containment purposes. The vessel has a steel liner that is internally reinforced with throttle and gusset steel plates and wrapped with a basalt fiber∕epoxy composite. The vessel design is fairly complex, including many geometric details and several components with different material models. The objective of this work is to determine an accurate and efficient procedure for modeling this type of vessels. This model can be used within an iterative optimization process. Different modeling approaches using various combinations of element types, material models, and geometric details are explored. Results of these models are compared to available experimental data. Accuracy and computational time between all these models are also compared. A suitable modeling method is recommended based on these findings.

Head Shape and Winding Angle Optimization of Composite Pressure Vessels Based on a Multi-level Strategy

This paper presents a multi-level strategy for the optimization of composite pressure vessels with nonmetallic liners. The design variables for composite vessels include the head shape, the winding angle, the layer thickness, the number of layers, and the stacking sequence. A parameter called “modified shape factor” is introduced as an objective function. This parameter takes into account the effects of the internal pressure and volume, the vessel weight, and the composite material properties. The proposed algorithm uses genetic algorithm and finite element analysis to optimize the design parameters. As a few examples, this procedure is implemented on geodesic and ellipsoidal heads. The results show that for the given vessel conditions, the geodesic head shape with helical winding angle of nine degrees has the better performance.

Abstract 2148: Sirolimus-eluting Stent Versus Bare-metal Stent In Diabetic Patients: Results Of The Italian Multicenter, Randomized “Dessert” Study.

Background: The real benefit of DES in diabetic patients is still debated since few studies have performed a direct randomized comparison between DES and BMS in such a population. Methods : The “Dessert” study is a multicenter, randomized trial conducted in Italy to demonstrate the efficacy of sirolimus-eluting stents (SES) compared to BMS in de novo lesions in native coronary arteries of diabetic patients, treated with insulin and/or oral antidiabetics for at least 3 months. Intraprocedural abciximab or pre-procedural tirofiban were administered to all patients. The primary end point was in-stent late loss as assessed by centralized quantitative coronary angiography at 8-month follow up. Centrally adjudicated composite MACE (death, Q wave and non-Q wave myocardial infarction, emergent bypass surgery or repeat target lesion revascularization) and target vessel failure (TVF: death, treated vessel related AMI, TLR) at 30 days, 9 and 12 months, and binary restenosis 8 months post-procedure were the secondary endpoints. Results: One hundred fifty patients were randomized to SES (75 patients, 109 lesions) or BMS (75 patients, 109 lesions). The two groups were well balanced for clinical, anatomic and procedural characteristics. On average, 45% of patients had multivessel or multilesion PCI, reference diameter was 2.66±0.43 mm and lesion length was 14.9±7.1 mm. In-stent late lumen loss was reduced from 0.96±0.61 mm for BMS to 0.14±0.33 mm for SES (p&lt;0.001); in-segment binary restenosis resulted 38.8% vs 3.6% respectively (p&lt;0.001). Twelve-month clinical events were significantly lower in the sirolimus group: MACE 22.1% vs 38.6%, p=0.035; TLR 5.9% vs 30%, p&lt;0.001; TVF 14.7% vs 34.3%, p=0.008. One case of subacute stent thrombosis occurred in sirolimus group, and one late stent thrombosis in bare-metal group. At multivariable analysis, stent type confirmed as independent predictor of in-segment late loss (p&lt;0.001), binary restenosis (p&lt;0.001), 12 month TVF (p=0.010) and 12-month MACE (p=0.037). Conclusions: The randomized “Dessert” study demonstrated that SES are safe and efficacious in reducing both angiographic and clinical parameters of restenosis compared with BMS in diabetic patients with de novo 1 or 2 vessel coronary stenoses.

Applications of Digital Correlation Method to Structure Inspection

In structure inspections, applications of optical techniques are rare, but the advantages of a non-contact, full field technique using a simple apparatus are attractive. The main requirements for structure inspection are the full-field strain measurement with the required precision and on-site measurement ability. The digital correlation method (DCM), a new optical deformation measurement tool, can satisfy all of the requirements for structure inspection. A smoothing algorithm which can greatly improve the strain measurement precision, and a 3-D DCM have been developed in this paper. For verifying this improvement, a comparison of strain measurements by computer-simulated speckle images has been carried out. Additionally, three structure inspection examples that cover typical materials and structure styles are presented: the interface shear stress distribution for reinforced concrete piles bedded on rock, the 3-D strain distribution of a composite vessel structure, and stresses in a hookup that connects two steel bridge structures. All the examples show that the new structural inspection tool is exemplary and illustrates the obvious advantages of this optical non-destructive technique.

Process-Induced Stress Analysis of Composite Wound Vessel with Metal Liner during Curing Process Using Semi-Analytical Hamiltonian Method

In accordance with Helliger-Reissner variational principle, a semi-analytical Hamiltonian method has been developed for analyzing the process-induced stress analysis of composite wound vessel with metal liner during the curing process. A typical numerical result indicates that the process-induced thermo-stress fields involve complex variations of gradient and multi-peak values at different stages during the curing process.