Rift jump and microcontinent formation in back-arc settings

Back-arc basins often present multiple spreading centres that form one after the other (e.g. Mariana subduction zone), propagate and rotate (e.g., Lau Basin) following trench retreat. In some cases, rift jumps can create continental fragments or microcontinents (e.g., Coral Sea, Central Mediterranean, Scotia Sea). The processes controlling rift jumps and possible formation of continental fragments are still not fully understood, but they are certainly related to the dynamics of subduction. In this work, we show how episodic trench retreat shapes the morphology of back-arc basins and can produce rift jumps. We use the finite element code ASPECT to model the rifting of continental lithosphere in 2D with boundary conditions that simulate the asymmetric type of extension caused by the trench retreat. We perform a parametric study in which we systematically vary the duration of different extensional phases, simulating episodes of trench retreat. Our results show that when extension is continuous, continental break-up occurs and a spreading centre develops. On the other hand, rift jump occurs in models with multiple extensional phases resulting in more complex morphologies that go from a hyperextend margin, to microcontinent formation, to spreading centre jumps within the newly formed oceanic lithosphere. In the first two cases (i.e., hyperextended margin and microcontinent), the length of the rift jump ranges from about 40 to 100 km and the timing varies from about 2 to 6 Myr. In the latter case (i.e., spreading centre jump within oceanic lithosphere) the length of the jump is significantly lower, 10-15 km, and the time needed for the ridge jump to occur is <2 Myr. These values depend on the rheological properties of the lithosphere, but, importantly, we show that the resulting scenario is controlled by the duration of the first extension stage and of the break before the next one.

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Analysis of Wrinkled Membranes Bounded With Macro-Fiber Composite (MFC) Actuators

ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, Volume 1 ◽

10.1115/smasis2010-3782 ◽

2010 ◽

Cited By ~ 3

Author(s):

Alireza Doosthoseini ◽

Armaghan Salehian ◽

Matthew Daly

Keyword(s):

Finite Element ◽

Fiber Composite ◽

The Other ◽

Horizontal Direction ◽

Finite Element Code ◽

Rectangular Shape ◽

Macro Fiber Composite

In this paper we focus on a study which involves quantifying the effects of Macro Fiber Composite (MFC) actuators on the pattern and magnitude of wrinkles in a membrane when exposed to various loadings. An ABAQUS finite element code is employed for this research. The membrane in this study has a rectangular shape which is clamped at one edge and is free to move in the horizontal direction at the other edge. MFC actuators are bounded to the membrane to make a bimorph configuration.

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Final Results of an Analytical Round Robin Exercise to Support Constraint Effects

Volume 6: Materials and Fabrication, Parts A and B ◽

10.1115/pvp2009-77722 ◽

2009 ◽

Cited By ~ 1

Author(s):

Marc Scibetta ◽

Eberhard Altstadt ◽

Rogelio Herna´ndez Callejas ◽

Bong-Sang Lee ◽

Naoki Miura ◽

...

Keyword(s):

Finite Element ◽

Round Robin ◽

Pressure Vessels ◽

Nuclear Industry ◽

The Other ◽

Reference Temperature ◽

Finite Element Code ◽

Input File ◽

Deep Crack ◽

Reactor Pressure

There is strong interest from the nuclear industry to use the precracked Charpy single-edge notched bend, SE(B), specimen (PCVN) to enable determination of the reference temperature, T0, with reactor pressure vessel surveillance specimens. Unfortunately, for many different ferritic steels, tests with the PCVN specimen (10×10×55 mm) have resulted in T0 temperatures up to 25°C lower than T0 values obtained using data from compact, C(T), specimens. This difference in T0 reference temperature has often been designated a specimen bias effect, and the primary focus for explaining this effect is loss of constraint in the PCVN specimen. The International Atomic Energy Agency has developed a three-part coordinated research project (CRP) to evaluate various issues associated with the fracture toughness Master Curve for application to light-water reactor pressure vessels. One part of the CRP is focused on the issue of test specimen geometry effects, with emphasis on the PCVN bias. This topic area was organized in two parts, an experimental part and an analytical part with a view towards each part complementing the other. Within the analytical part, elastic plastic finite element methods are extensively used in order to access local stress and strain information that is the basic ingredient for most of the micromodels of cleavage fracture developed to date. In the framework of the international qualification and acceptance of such a tool for actual loss of constraint prediction, the validation of such tool is of prime importance. Therefore, a round robin exercise has been proposed and performed by ten laboratories from nine different countries. The round robin focuses on the modeling of realistic three-dimensional geometries containing shallow and deep crack. This round robin has been useful to qualify different finite element codes and to identify possible errors in the input file. The round robin demonstrates that errors in the input file can be easily introduced. Some remaining differences cannot be attributed to one particular finite element code or to actual errors. Those differences are attributed to the so called “user effect” which can only be reduced through in depth discussion and deep understanding of each finite element code. Independently of the used code and of relatively small user effect differences, it is found that shallow crack specimens are more sensitive to loss of constraint than deep crack specimens for a given specimen size. The difference in terms of reference temperature between the two geometries is evaluated to be about 40 °C. For a deep crack, loss of constraint is identified to appear at M values around 200. This value is larger than the one specified in current standard (M = 30). Increasing the M value to 200 will jeopardize the use of PCVN for the nuclear industry on the other hand bias introduced by M value of 30 is acceptable.

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Linking subduction dynamics to back-arc deformation

10.5194/egusphere-egu2020-7092 ◽

2020 ◽

Author(s):

Valentina Magni ◽

Manel Prada

Keyword(s):

Boundary Conditions ◽

Numerical Models ◽

Thermal Structure ◽

Oceanic Lithosphere ◽

Lau Basin ◽

Crustal Composition ◽

Lithospheric Extension ◽

Back Arc ◽

Existing Structure ◽

Tyrrhenian Basin

The morphology of back-arc basins shows how complex their formation is and how pre-existing lithospheric structures, rifting and spreading processes, and subduction dynamics all have a role in shaping them. Often, back-arc basins present multiple spreading centres that form one after the other (e.g. Mariana subduction zone), propagate and rotate (e.g., Lau Basin) following trench retreat. Episodes of fast and slow trench retreat can cause rift jumps, migration of magmatism, and pulses of higher crustal production (e.g., Tyrrhenian Basin). The evolution of a back-arc basin is not only tightly linked to subduction dynamics, but it is likely that the composition and the pre-existing structure of the lithosphere play a role in shaping the basin too. In this work, we investigate the interplay between these features with numerical models of lithospheric extension with a visco-plastic rheology. We use the finite element code ASPECT to model the rifting of continental and oceanic lithosphere with boundary conditions that simulate the asymmetric type of extension caused by the trench retreat. We perform a parametric study in which we systematically change key parameters such as crustal composition and thickness, initial thermal structure and rheology of the lithosphere, and rate of extension. These models aim at understanding how pre-existing lithospheric structures affect back-arc rifting and spreading and what processes control spreading centres jumps in back-arc settings. Preliminary results show that time-dependent boundary conditions that simulate episodes of fast trench retreat, thus fast extension, play an important role into the style of lithospheric back-arc deformation. Finally, we will compare our model results with the location and timing of back-arc rifting and spreading in different active and inactive back-arc basins.

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Modeling of Spud-Can Penetration and Uplift Using the Coupled Eulerian-Lagrangian Technique

29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 1 ◽

10.1115/omae2010-20448 ◽

2010 ◽

Author(s):

Deepak V. Datye

Keyword(s):

Finite Element ◽

Finite Elements ◽

Large Strain ◽

The Other ◽

Finite Element Code ◽

Element Mesh ◽

Strain Gradients ◽

Plastic Deformations ◽

Soil Lead ◽

Eulerian Methods

The penetration of spudcans in soil is associated with large plastic deformations of the soil. Finite element methods that are based on Lagrangian techniques often fail when large strain gradients in the soil lead to excessive distortions of the finite elements. Eulerian methods, on the other hand, allow material to flow across the finite element mesh and, hence, can be used to model such problems. In this work the Coupled Eulerian-Lagrangian technique, which is available in the Abaqus finite element code, has been used to model the penetration of spudcans in soil. The spudcan has been modeled as a Lagrangian body, and the soil as an Eulerian material that interacts with the Lagrangian body. Data on the resistance offered by the soil as the spudcan is uplifted, rotated, and moved horizontally are obtained. These resistance values can potentially be used as elastic-plastic joint stiffnesses in analyses in which the soil is not physically modeled.

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Joints representation strategy: performance evaluation by a Finite Element code. A feasibility analysis of a tunnel infrastructure in the Carnian Alps

Rendiconti online della Società Geologica Italiana ◽

10.3301/rol.2016.161 ◽

2016 ◽

Vol 41 ◽

pp. 333-336 ◽

Cited By ~ 1

Author(s):

Giacomo Tedesco ◽

Lisa Borgatti ◽

Stefano Bonduà ◽

Gianluca Marcato

Keyword(s):

Finite Element ◽

Performance Evaluation ◽

Feasibility Analysis ◽

Finite Element Code ◽

Strategy Performance

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THE USE OF AN OPEN SOURCE FINITE ELEMENT CODE FOR AEROELASTIC ANALYSES

10.26678/abcm.encit2016.cit2016-0182 ◽

2016 ◽

Author(s):

Adolfo Gomes Marto ◽

João Luiz F. Azevedo

Keyword(s):

Finite Element ◽

Open Source ◽

Finite Element Code

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Finite element analysis of reinforced concrete deep beam with large opening

Beni-Suef University Journal of Basic and Applied Sciences ◽

10.1186/s43088-021-00104-z ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Elsayed Ismail ◽

Mohamed S. Issa ◽

Khaled Elbadry

Keyword(s):

Finite Element ◽

Reinforced Concrete ◽

Concrete Beams ◽

Load Capacity ◽

Reinforced Concrete Beams ◽

The Other ◽

Deep Beam ◽

Web Openings ◽

Design Load ◽

Large Opening

Abstract Background A series of nonlinear finite element (FE) analyses was performed to evaluate the different design approaches available in the literature for design of reinforced concrete deep beam with large opening. Three finite element models were developed and analyzed using the computer software ATENA. The three FE models of the deep beams were made for details based on three different design approaches: (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978), (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006), and Strut and Tie method (STM) as per ACI 318-14 (ACI318 Committee, Building Code Requirements for Structural Concrete (ACI318-14), 2014). Results from the FE analyses were compared with the three approaches to evaluate the effect of different reinforcement details on the structural behavior of transfer deep beam with large opening. Results The service load deflection is the same for the three models. The stiffnesses of the designs of (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and STM reduce at a load higher than the ultimate design load while the (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) reduces stiffness at a load close to the ultimate design load. The deep beam designed according to (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) model starts cracking at load higher than the beam designed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) method. The deep beam detailed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) and (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) failed due to extensive shear cracks. The specimen detailed according to STM restores its capacity after initial failure. The three models satisfy the deflection limit. Conclusion It is found that the three design approaches give sufficient ultimate load capacity. The amount of reinforcement given by both (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) is the same. The reinforcement used by the STM method is higher than the other two methods. Additional reinforcement is needed to limit the crack widths. (Mansur, M. A., Design of reinforced concrete beams with web openings, (2006)) method gives lesser steel reinforcement requirement and higher failure load compared to the other two methods.

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Stress Analysis of Cement Concrete Pavement under Overweight Loads

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.446-449.949 ◽

2012 ◽

Vol 446-449 ◽

pp. 949-953

Author(s):

Ya Ni Lu ◽

Tao Li Xiao

Keyword(s):

Finite Element ◽

Regression Analysis ◽

Finite Element Model ◽

Element Model ◽

Concrete Pavement ◽

The Other ◽

Tension Stress ◽

Statistical Regression ◽

Cement Concrete ◽

Cement Concrete Pavement

Special load has produced serious damage to the concrete pavement because of the great gross weight and heavy axle load, but the present specification has not mentioned this kind of load. On this occasion, Several conditions of critical load are identified through ANSYS finite element model analysis and the formula through statistical regression analysis to the bottom maximum tension stress is drawn up. Which can not only guide the concrete pavement design under the special load but also the result may be referred by the other kinds of engineering.

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