Structural Integrity of Hydrogen Storage Tanks at Pre-Stressing and Operating Pressures

2005 ◽  
Author(s):  
J. L. Parham ◽  
Y. B. Guo ◽  
W. H. Sutton
Keyword(s):  
Hydrogen Storage ◽  
Stress Level ◽  
Structural Integrity ◽  
Real Life ◽  
Peak Stress ◽  
Operating Pressure ◽  
Middle Section ◽  
Element Analysis ◽  
Residual Strains ◽  
Simulation Results

With the fuel prices reaching record highs and ever-increasing tighter environmental policies, hydrogen-powered vehicles have great potential to substantially increase overall fuel economy, reduce vehicle emissions, and decrease dependence on foreign oil imports. While hydrogen fuel is exciting for automotive industries due to its potentials of significant technical and economic advantages, design and manufacture safe and reliable hydrogen tanks is recognized as the number one priority in hydrogen technology development and deployment. Real life testing of tank performance is extremely useful, but very time consuming, expensive, and lacks a rigorous scientific basis, which prohibits the development of a more reliable hydrogen tank. However, very few testing and simulation results can be found in public literature. This paper focused on the development of an efficient finite element analysis (FEA) tool to provide a more economical alternative for hydrogen tank analysis, though it may not be an all-out replacement for physical testing. A FEA model has been developed for the hydrogen tank with 6061-T6 aluminum liner and carbon-fiber/epoxy shell to investigate the tank integrity at pre-stresses of 45.5 MPa, 70 MPa, and 105 MPa and operating pressures of 35 MPa, 70 MPa, and 105 MPa. The residual stresses induced by different pre-stresses are at the equivalent level in the middle section but vary significantly in other tank sections. Residual stress magnitudes may saturate at a certain pre-stress level. In contrast, the residual strains in the middle section increases with pre-stress. The simulation results indicate that the optimal pre-stress level depends on the specific operating pressure to enhance tank integrity. A certain area of the neck and the top and bottom domes also experiences peak stress and strain at pre-stressing and regular operating pressures. The research findings may help manufacturing industries to build safety into manufacturing practices of hydrogen storage infrastructures.

Development of Stress Intensification Factors for Collared Type Piping Joints

2020 ◽  
Author(s):  
Cameron Ewing
Keyword(s):  
Finite Element ◽  
Carbon Steel ◽  
Electrode Materials ◽  
Real Life ◽  
Strain Curve ◽  
Bending Moment ◽  
Peak Stress ◽  
Point Load ◽  
Element Analysis ◽  
Transfer Lines

Abstract Stress Intensification Factors or SIFs allow piping to be analyzed using beam theory, with a SIF representing local effects of specific piping geometry. However, the current piping codes do not explicitly provide SIFs for collared type piping joints for use in pipe stress calculations. The objective of this paper is to describe the methodology on how a finite element analysis (FEA) was to model the behavior of collared joints, and to ultimately develop appropriate SIFs that can be used in pipe stress analyses. This paper describes a real-life analysis example on collared joints installed on a set of existing fuel transfer lines. The lines, which ranged in size from DN200 to DN350, were concrete lined carbon steel with the collars fillet welded to the carbon steel section of the piping. Test coupons cut from existing pipe-collar sections were tested in a laboratory to determine the forces required to break the collar welds. Using FEA, the same test coupons were modelled to replicate the failure tests. Multiple iterations were undertaken to determine an appropriate bi-linear stress-strain curve fit for the weld material. The curves of different weld electrode materials were considered. The curve which lead to results similar to those observed in physical testing was selected. From this, a failure stress across the weld could be determined. This stress, 435MPa was then used in subsequent models to determine the point at which the weld fails under bending loads. Multiple tests were analyzed to allow for possible effects of inclusions and voids. Finite element models of the collar geometries were constructed and non-linear analyses were undertaken using the weld strengths determined from the coupon testing data. A simple cantilever type arrangement with a point load at one end was analyzed, inducing a bending moment across the collar. The peak stress resulting from the bending moment across the collar weld at the center of the cantilevered pipe arrangement, was investigated across various pipe diameters, wall thicknesses, weld sizes and collar geometries. Based on the results, a relationship between the pipe geometry and SIF was developed. Hence a pipe stress model of the transfer lines could ultimately be developed using these SIFs to predict the behavior of the piping.

Structural Integrity of Composite-Lined Hydrogen Storage Tanks at Operating Pressures

2007 ◽  
Author(s):  
Y. B. Guo ◽  
J. L. Parham
Keyword(s):  
Structural Integrity ◽  
Real Life ◽  
Elastic Behavior ◽  
Attractive Alternative ◽  
Element Analysis ◽  
Hydrogen Technology ◽  
Load Release ◽  
Design And Manufacture ◽  
Carbon Fiber Epoxy ◽  
Economical Alternative

Hydrogen may appear to be an attractive alternative fuel due to its obvious environmental and potentials of significant technical and economic advantages, the design and manufacture a safe and reliable hydrogen tank is the number one priority for development and deployment of hydrogen technology. Compared with aluminum-lined hydrogen tanks, composite tanks offer advantages of lightweight and conformability. Real life tank testing is very expensive and time consuming. In this study, a finite element analysis (FEA) tool has been developed to provide a more economical alternative for composite hydrogen tank analysis at operating pressures of 35 MPa, 45 MPa, and 70 MPa. It was found that the carbon-fiber/epoxy shell acts as the primary structural member, unlike an aluminum-lined tank where the liner acts performs this function. Critical portions of the tanks were found to be the top and bottom domes as well as the interaction between the liner and boss. Some slight plastic deformation was found to occur in the liner at 70 MPa, though under the 35 MPa and 45 MPa loads, the liner exhibited only elastic behavior. The shell elastically deformed in all loading cases, which results in very low residual stress and strain values following the load release. The results may help manufacturers improve tank safety in the design and manufacture of composite hydrogen.

Viscoelastic Response of HTPB Based Solid Fuel to Horizontal and Vertical Storage Slumping Conditions and it's Affect on Service Life

2012 ◽  
Vol 510-511 ◽  
pp. 22-31
Author(s):  
Qamar Nawaz ◽  
F. Nizam
Keyword(s):  
Service Life ◽  
Solid Fuel ◽  
Structural Integrity ◽  
Space Vehicle ◽  
Storage Condition ◽  
Storage Conditions ◽  
Fuel System ◽  
Successful Operation ◽  
Element Analysis ◽  
Simulation Results

Frequent use of solid fuels as thrust generating energy source in modern day space vehicle systems has created a need to assess their serviceability for long term storage under various conditions. Solid fuel grain, the most important part of any solid fuel system, responds viscoelastically to any loading condition. For the assessment of the service life of any solid fuel system, the solid fuel grain has to be structurally evaluated in applied storage conditions. Structural integrity of the grain is exceptionally significant to guarantee the successful operation of the solid fuel system. In this work, numerical simulations have been performed to assess the mechanical stresses and strains induced in an HTPB based solid fuel grain during service life employing ABAQUS standard FEA software using 4-node bilinear quadrilateral elements. For finite element analysis (FEA), typical 2-D and π/nthaxisymmetric section of 5-point (n) star grain geometry is considered. Mechanical loads include the horizontal or vertical 1-g (solid fuel weight) storage condition. The simulation results are compared with the analytical results for the same grain geometry. Analytically measured slump deflections in grain segment at various storage times have been found in good relation with the FEA based simulation results. This proves the validity of the procedure adopted and is helpful in assessment of the service life of solid fuel systems.

scholarly journals Finite element analysis of the performance of additively manufactured scaffolds for scapholunate ligament reconstruction

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0256528
Author(s):  
Nataliya Perevoshchikova ◽  
Kevin M. Moerman ◽  
Bardiya Akhbari ◽  
Randy Bindra ◽  
Jayishni N. Maharaj ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Integrity ◽  
Functional Limitations ◽  
Peak Stress ◽  
Surgical Reconstruction ◽  
Patient Specific ◽  
Element Analysis ◽  
Interosseous Ligament ◽  
Wrist Motion

Rupture of the scapholunate interosseous ligament can cause the dissociation of scaphoid and lunate bones, resulting in impaired wrist function. Current treatments (e.g., tendon-based surgical reconstruction, screw-based fixation, fusion, or carpectomy) may restore wrist stability, but do not address regeneration of the ruptured ligament, and may result in wrist functional limitations and osteoarthritis. Recently a novel multiphasic bone-ligament-bone scaffold was proposed, which aims to reconstruct the ruptured ligament, and which can be 3D-printed using medical-grade polycaprolactone. This scaffold is composed of a central ligament-scaffold section and features a bone attachment terminal at either end. Since the ligament-scaffold is the primary load bearing structure during physiological wrist motion, its geometry, mechanical properties, and the surgical placement of the scaffold are critical for performance optimisation. This study presents a patient-specific computational biomechanical evaluation of the effect of scaffold length, and positioning of the bone attachment sites. Through segmentation and image processing of medical image data for natural wrist motion, detailed 3D geometries as well as patient-specific physiological wrist motion could be derived. This data formed the input for detailed finite element analysis, enabling computational of scaffold stress and strain distributions, which are key predictors of scaffold structural integrity. The computational analysis demonstrated that longer scaffolds present reduced peak scaffold stresses and a more homogeneous stress state compared to shorter scaffolds. Furthermore, it was found that scaffolds attached at proximal sites experience lower stresses than those attached at distal sites. However, scaffold length, rather than bone terminal location, most strongly influences peak stress. For each scaffold terminal placement configuration, a basic metric was computed indicative of bone fracture risk. This metric was the minimum distance from the bone surface to the internal scaffold bone terminal. Analysis of this minimum bone thickness data confirmed further optimisation of terminal locations is warranted.

scholarly journals Finite element analysis of the performance of additively manufactured scaffolds for scapholunate ligament reconstruction

2021 ◽  
Author(s):  
Nataliya Perevoshchikova ◽  
Kevin Mattheus Moerman ◽  
Bardiya Akhbari ◽  
David J. Saxby ◽  
Jayishni N. Maharaj ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Integrity ◽  
Functional Limitations ◽  
Peak Stress ◽  
Surgical Reconstruction ◽  
Patient Specific ◽  
Element Analysis ◽  
Interosseous Ligament ◽  
Wrist Motion

Rupture of the scapholunate interosseous ligament can cause the dissociation of scaphoid and lunate bones, resulting in impaired wrist function. Current treatments (e.g., tendon-based surgical reconstruction, screw-based fixation, fusion, or carpectomy) may restore wrist stability, but do not address regeneration of the ruptured ligament, and may result in wrist functional limitations and osteoarthritis. Recently a novel multiphasic bone-ligament-bone scaffold was proposed, which aims to reconstruct the ruptured ligament, and which can be 3D-printed using medical-grade polycaprolactone. This scaffold is composed of a central ligament-scaffold section and features a bone attachment terminal at either end. Since the ligament-scaffold is the primary load bearing structure during physiological wrist motion, its geometry, mechanical properties, and the surgical placement of the scaffold are critical for performance optimisation. This study presents a patient-specific computational biomechanical evaluation of the effect of scaffold length, and positioning of the bone attachment sites. Through segmentation and image processing of medical image data for natural wrist motion, detailed 3D geometries as well as patient-specific physiological wrist motion could be derived. This data formed the input for detailed finite element analysis, enabling computational of scaffold stress and strain distributions, which are key predictors of scaffold structural integrity. The computational analysis demonstrated that longer scaffolds present reduced peak scaffold stresses and a more homogeneous stress state compared to shorter scaffolds. Furthermore, it was found that scaffolds attached at proximal sites experience lower stresses than those attached at distal sites. However, scaffold length, rather than bone terminal location, most strongly influences peak stress. For each scaffold terminal placement configuration, a basic metric was computed indicative of bone fracture risk. This metric was the minimum distance from the bone surface to the internal scaffold bone terminal. Analysis of this minimum bone thickness data confirmed further optimisation of terminal locations is warranted.

Tire Bead Overheating in Urban Buses and Trucks Using Drum Brake Systems

1998 ◽  
Vol 26 (1) ◽  
pp. 51-62
Author(s):  
A. L. A. Costa ◽  
M. Natalini ◽  
M. F. Inglese ◽  
O. A. M. Xavier
Keyword(s):  
Heat Transfer ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Energy ◽  
Structural Integrity ◽  
Experimental Temperature ◽  
Temperature Profiles ◽  
Element Analysis ◽  
Drum Brake ◽  
Fea Model

Abstract Because the structural integrity of brake systems and tires can be related to the temperature, this work proposes a transient heat transfer finite element analysis (FEA) model to study the overheating in drum brake systems used in trucks and urban buses. To understand the mechanics of overheating, some constructive variants have been modeled regarding the assemblage: brake, rims, and tires. The model simultaneously studies the thermal energy generated by brakes and tires and how the heat is transferred and dissipated by conduction, convection, and radiation. The simulated FEA data and the experimental temperature profiles measured with thermocouples have been compared giving good correlation.

scholarly journals Potential and limitations of finite element modelling in assessing structural integrity of coralline algae under future global change

2015 ◽  
Vol 12 (19) ◽  
pp. 5871-5883 ◽  
Author(s):  
L. A. Melbourne ◽  
J. Griffin ◽  
D. N. Schmidt ◽  
E. J. Rayfield
Keyword(s):  
Climate Change ◽  
Finite Element ◽  
Structural Integrity ◽  
Geometric Model ◽  
Algal Growth ◽  
Coralline Algae ◽  
Rocky Shores ◽  
Element Analysis ◽  
Scan Data ◽  
The Impact

Abstract. Coralline algae are important habitat formers found on all rocky shores. While the impact of future ocean acidification on the physiological performance of the species has been well studied, little research has focused on potential changes in structural integrity in response to climate change. A previous study using 2-D Finite Element Analysis (FEA) suggested increased vulnerability to fracture (by wave action or boring) in algae grown under high CO2 conditions. To assess how realistically 2-D simplified models represent structural performance, a series of increasingly biologically accurate 3-D FE models that represent different aspects of coralline algal growth were developed. Simplified geometric 3-D models of the genus Lithothamnion were compared to models created from computed tomography (CT) scan data of the same genus. The biologically accurate model and the simplified geometric model representing individual cells had similar average stresses and stress distributions, emphasising the importance of the cell walls in dissipating the stress throughout the structure. In contrast models without the accurate representation of the cell geometry resulted in larger stress and strain results. Our more complex 3-D model reiterated the potential of climate change to diminish the structural integrity of the organism. This suggests that under future environmental conditions the weakening of the coralline algal skeleton along with increased external pressures (wave and bioerosion) may negatively influence the ability for coralline algae to maintain a habitat able to sustain high levels of biodiversity.

scholarly journals Geometrical Effects on Ultrasonic Al Bump Direct Bonding for Microsystem Integration: Simulation and Experiments

Micromachines ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 750
Author(s):  
Jun-Hao Lee ◽  
Pin-Kuan Li ◽  
Hai-Wen Hung ◽  
Wallace Chuang ◽  
Eckart Schellkes ◽  
...  
Keyword(s):  
Shear Strength ◽  
Joint Strength ◽  
Maximum Stress ◽  
Geometrical Parameters ◽  
Experimental Demonstration ◽  
Joint Shear Strength ◽  
Element Analysis ◽  
Ultrasonic Bonding ◽  
Simulation Results ◽  
Geometrical Effects

This study employed finite element analysis to simulate ultrasonic metal bump direct bonding. The stress distribution on bonding interfaces in metal bump arrays made of Al, Cu, and Ni/Pd/Au was simulated by adjusting geometrical parameters of the bumps, including the shape, size, and height; the bonding was performed with ultrasonic vibration with a frequency of 35 kHz under a force of 200 N, temperature of 200 °C, and duration of 5 s. The simulation results revealed that the maximum stress of square bumps was greater than that of round bumps. The maximum stress of little square bumps was at least 15% greater than those of little round bumps and big round bumps. An experimental demonstration was performed in which bumps were created on Si chips through Al sputtering and lithography processes. Subtractive lithography etching was the only effective process for the bonding of bumps, and Ar plasma treatment magnified the joint strength. The actual joint shear strength was positively proportional to the simulated maximum stress. Specifically, the shear strength reached 44.6 MPa in the case of ultrasonic bonding for the little Al square bumps.

scholarly journals Computational and experimental mechanical performance of a new everolimus-eluting stent purpose-built for left main interventions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saurabhi Samant ◽  
Wei Wu ◽  
Shijia Zhao ◽  
Behram Khan ◽  
Mohammadali Sharzehee ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Patient Specific ◽  
Wall Structure ◽  
Left Main ◽  
Element Analysis ◽  
Stent Expansion ◽  
Radial Strength ◽  
Different Diameters

AbstractLeft main (LM) coronary artery bifurcation stenting is a challenging topic due to the distinct anatomy and wall structure of LM. In this work, we investigated computationally and experimentally the mechanical performance of a novel everolimus-eluting stent (SYNERGY MEGATRON) purpose-built for interventions to large proximal coronary segments, including LM. MEGATRON stent has been purposefully designed to sustain its structural integrity at higher expansion diameters and to provide optimal lumen coverage. Four patient-specific LM geometries were 3D reconstructed and stented computationally with finite element analysis in a well-validated computational stent simulation platform under different homogeneous and heterogeneous plaque conditions. Four different everolimus-eluting stent designs (9-peak prototype MEGATRON, 10-peak prototype MEGATRON, 12-peak MEGATRON, and SYNERGY) were deployed computationally in all bifurcation geometries at three different diameters (i.e., 3.5, 4.5, and 5.0 mm). The stent designs were also expanded experimentally from 3.5 to 5.0 mm (blind analysis). Stent morphometric and biomechanical indices were calculated in the computational and experimental studies. In the computational studies the 12-peak MEGATRON exhibited significantly greater expansion, better scaffolding, smaller vessel prolapse, and greater radial strength (expressed as normalized hoop force) than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY (p < 0.05). Larger stent expansion diameters had significantly better radial strength and worse scaffolding than smaller stent diameters (p < 0.001). Computational stenting showed comparable scaffolding and radial strength with experimental stenting. 12-peak MEGATRON exhibited better mechanical performance than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY. Patient-specific computational LM stenting simulations can accurately reproduce experimental stent testing, providing an attractive framework for cost- and time-effective stent research and development.

Measurement of Residual Stresses in Linear Friction Welded In-Service Inconel 718 Superalloy

2016 ◽  
Vol 879 ◽  
pp. 1800-1806 ◽  
Author(s):  
M. Smith ◽  
L. Bichler ◽  
D. Sediako
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Base Material ◽  
Peak Stress ◽  
Weld Interface ◽  
Aerospace Alloys ◽  
Aero Engine ◽  
Linear Friction ◽  
Inconel 718 Superalloy ◽  
Residual Strains

Measurement of residual strains by neutron diffraction of linear friction welded Inconel® 718 (IN 718) superalloy acquired from a mid-service aero-engine disk was undertaken in this study. Residual strain and stress throughout the various weld regions including the heat affected zone (HAZ), thermomechanical affected zone (TMAZ) and dynamically recrystallized zone (DRX) were characterized. The residual stresses were observed to increase from the base material to the weld interface, with a peak stress at the weld interface in all orthogonal directions. The trends for residual stress across the weld are in agreement with other work published in literature for solid state welding of aerospace alloys, where high residual stresses were commonly reported at the weld interface.

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