Finite element study of uplift and strain across Vancouver Island

1994 ◽  
Vol 31 (10) ◽  
pp. 1510-1522 ◽  
Author(s):  
Kelin Wang ◽  
Herb Dragert ◽  
H. Jay Melosh
Keyword(s):  
Finite Element ◽  
Surface Deformation ◽  
Viscoelastic Model ◽  
Vancouver Island ◽  
Slip Zone ◽  
Recurrence Time ◽  
Dislocation Model ◽  
Stick Slip ◽  
Geological Evidence ◽  
Geophysical Surveys

Geological evidence for sudden coastal subsidence along the west coast of southern Vancouver Island points to the occurrence of great prehistorical subduction earthquakes. Contemporary uplift and crustal shortening patterns in southern Vancouver Island appear to indicate that the subduction megathrust fault is currently locked. To understand better the dynamics of the observed surface deformation, we develop a finite element model of earthquake cycles for the northern Cascadia subduction zone across southern Vancouver Island, using a linear viscoelastic rheology. The model consists of the continental and oceanic lithospheres, the asthenospheric mantle with a viscosity of 5 × 1019 Pa∙s, and a low-viscosity (1018 Pa∙s) mantle wedge between the subducted oceanic plate and the overlying continental plate. The shallow geometry of the subducted Juan de Fuca plate is well defined by the results of various geophysical surveys, and the deep geometry is constrained by the results of seismic tomography. The model megathrust fault has a stick-slip zone near the surface, a viscoelastically weakly coupled zone (viscosity 7 × 1017 Pa∙s) at depth, and a narrow free-slip zone in between. Earthquakes are allowed to occur every 500 years. Varying the recurrence time does not greatly affect the surface deformation in the later part of the interseismic period. Experiments varying the width of the stick-slip zone lead to the conclusion that a width of about 70 km satisfies both the observed coseismic coastal subsidence and the contemporary surface deformation pattern. The results of a simple elastic dislocation model for thrust earthquakes that had been previously applied to the region are compared with the solutions of the viscoelastic model. Despite its simplicity, the elastic model approximates well the surface deformation of the viscoelastic model in the second half of the interseismic period, although it predicts a slightly narrower stick-slip zone of the fault. The present viscoelastic model is limited principally by the two-dimensional approach, the assumptions of purely stick-slip behaviour of the thrust fault, and the uncertainties in rock rheology.

The Dellwood knolls and their role in triple junction tectonics off northern Vancouver Island

1980 ◽  
Vol 17 (5) ◽  
pp. 577-593 ◽  
Author(s):  
R. P. Riddihough ◽  
R. G. Currie ◽  
R. D. Hyndman
Keyword(s):  
Triple Junction ◽  
Plate Tectonics ◽  
Vancouver Island ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Geological Evidence ◽  
Topographic Features ◽  
Narrow Valley ◽  
The Pacific ◽  
Geophysical Surveys

The Dellwood knolls are two small topographic features on the ocean floor off northern Vancouver Island. They have been proposed as a spreading centre connecting the Explorer ridge to the Queen Charlotte fault and the location of a triple junction between the Pacific, American, and Juan de Fuca plate systems.Detailed geophysical surveys and ocean-bottom seismometer deployments confirm that they are the site of active seismicity and recent volcanism. Modelling of the magnetic anomaly field shows that it is almost entirely produced by normally magnetized material, supporting geological evidence that the knolls are probably less than 1 Ma old. Although the two knolls are separated by a narrow valley with some downfaulting, they do not form a clearly linear spreading rift.Assessment of their role in the plate tectonics of the region suggests that spreading at the knolls was initiated around 1 Ma ago in crust now 4.5 Ma old as part of a complex, northwesterly ridge migration process at the northern end of the Explorer ridge. Reconstruction of this process, which involves asymmetric spreading and ridge jumping, provides an explanation for the creation of the associated Paul Revere and Winona ridges.

scholarly journals Driving forces on dislocations: finite element analysis in the context of the non-singular dislocation theory

2021 ◽  
Author(s):  
Xiandong Zhou ◽  
Christoph Reimuth ◽  
Peter Stein ◽  
Bai-Xiang Xu
Keyword(s):  
Finite Element ◽  
Dislocation Loop ◽  
Driving Force ◽  
Complex Geometry ◽  
Driving Forces ◽  
Singular Solutions ◽  
Dislocation Model ◽  
Configurational Force ◽  
Element Analysis ◽  
Dislocation Configuration

AbstractThis work presents a regularized eigenstrain formulation around the slip plane of dislocations and the resultant non-singular solutions for various dislocation configurations. Moreover, we derive the generalized Eshelby stress tensor of the configurational force theory in the context of the proposed dislocation model. Based on the non-singular finite element solutions and the generalized configurational force formulation, we calculate the driving force on dislocations of various configurations, including single edge/screw dislocation, dislocation loop, interaction between a vacancy dislocation loop and an edge dislocation, as well as a dislocation cluster. The non-singular solutions and the driving force results are well benchmarked for different cases. The proposed formulation and the numerical scheme can be applied to any general dislocation configuration with complex geometry and loading conditions.

Finite Element Method-based geomechanical risk assessment of underground laboratory located in the deep copper mine

2021 ◽  
Author(s):  
Krzysztof Fulawka ◽  
Witold Pytel ◽  
Piotr Mertuszka ◽  
Marcin Szumny
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Analysis ◽  
New Technologies ◽  
Radiation Detection ◽  
Underground Laboratory ◽  
Design Stage ◽  
Copper Mine ◽  
Geophysical Surveys ◽  
Element Method

<p>Underground laboratories provide a unique environment for various industries and are a suitable place for developing new technologies for mining, geophysical surveys, radiation detection, as well as many other studies and measurements. Unfortunately, any operation in underground excavations is associated with exposure to many hazards not necessarily encountered in surface laboratories. One of the most dangerous events observed in underground conditions is the dynamic manifestation of rock mass pressure in form of rockburst, roof falls and mining tremors. Therefore, proper evaluation of geomechanical risk is a key element ensuring the safety of work in underground conditions. Finite Element Method-based numerical analysis is one of the tools which allow conducting a detailed geomechanical hazard assessment already at the object design stage. The results of such calculations may be the basis for the implementation of preventive measures before running up the underground facility.</p><p>Within this paper, the three-dimensional FEM-based numerical analysis of large-scale underground laboratory located in deep Polish copper mine was presented. The calculations were made with GTS NX software, which allowed determining the changes in the safety factor in surrounding of the analyzed area. Finally, the possibility of underground laboratory establishment, with respect to predicted stress and strain conditions, were determined.</p>

Finite Element Simulation and Experimental Study on Blow Forming of Plastic Cups

2011 ◽  
Vol 148-149 ◽  
pp. 1319-1322
Author(s):  
Xiao Hu ◽  
Yi Sheng Zhang ◽  
Hong Qing Li ◽  
De Qun Li
Keyword(s):  
Finite Element ◽  
Thickness Distribution ◽  
Viscoelastic Model ◽  
Engineering Practice ◽  
Fe Model ◽  
Thin Wall ◽  
Forming Process ◽  
Element Simulation ◽  
Physically Based ◽  
Set Up

Blow forming process of plastic sheets is simple and easy to realize, thus, it is widely used for plastic thin-wall parts. In the practical production, an effective method is needed for the preliminary set-up of process parameters in order to achieve accurate control of thickness distribution. Thus, a finite element method (FEM) code is used to simulate blow forming process. For better description of complex material theological characteristics, a physically based viscoelastic model (VUMAT forms Buckley model) to model the complex constitutive behavior is used. Nonlinear FE analyses using ABAQUS were carried out to simulate the blow forming process of plastic cups. The actual values at different locations show a satisfactory agreement with the simulation results: as a matter of fact the error along the cell mid-section did not exceed 0.02 mm on average, corresponding to 5% of the initial thickness, thus the FE model this paper can meet the requirements of the engineering practice.

scholarly journals Development and analytical validation of a finite element model of fluid transport through osteochondral tissue

2020 ◽  
Author(s):  
Brady D. Hislop ◽  
Chelsea M. Heveran ◽  
Ronald K. June
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Fluid Transport ◽  
Fluid Pressure ◽  
Viscoelastic Model ◽  
Element Model ◽  
Pressure Gradients ◽  
Superficial Zone ◽  
Bone Interface ◽  
Osteochondral Tissue

AbstractFluid transport between cartilage and bone is critical to joint health. The objective of this study was to develop and analytically validate a finite element model of osteochondral tissue capable of modeling cartilage-bone fluid transport. A biphasic viscoelastic model using an ellipsoidal fiber distribution was created with three distinct layers of cartilage (superficial zone, middle zone, and deep zone) along with a layer of subchondral bone. For stress-relaxation in unconfined compression, our results for compressive stress, radial stress, effective fluid pressure, and elastic recoil were compared with established biphasic analytical solutions. Our model also shows the development of fluid pressure gradients at the cartilage-bone interface during loading. Fluid pressure gradients developed at the cartilage-bone interface with consistently higher pressures in cartilage following initial loading to 10% strain, followed by convergence towards equal pressures in cartilage and bone during the 400s relaxation period. These results provide additional evidence that fluid is transported between cartilage and bone during loading and improves upon estimates of the magnitude of this effect through incorporating a realistic distribution and estimate of the collagen ultrastructure. Understanding fluid transport between cartilage and bone may be key to new insights about the mechanical and biological environment of both tissues in health and disease.

scholarly journals High-Velocity Shear and Soft Friction at the Nanometer Scale

2021 ◽  
Vol 7 ◽  
Author(s):  
Per-Anders Thorén ◽  
Riccardo Borgani ◽  
Daniel Forchheimer ◽  
David B. Haviland
Keyword(s):  
High Speed ◽  
Surface Deformation ◽  
Soft Materials ◽  
Lateral Force ◽  
Velocity Shear ◽  
Polymer Materials ◽  
Amplitude Dependence ◽  
Dynamic Force ◽  
Stick Slip ◽  
Soft Polymer

We study high-speed friction on soft polymer materials by measuring the amplitude dependence of cyclic lateral forces on the atomic force microscope (AFM) tip as it slides on the surface with fixed contact force. The resulting dynamic force quadrature curves separate the elastic and viscous contributions to the lateral force, revealing a transition from stick-slip to free-sliding motion as the velocity increases. We explain force quadratures and describe how they are measured, and we show results for a variety of soft materials. The results differ substantially from the measurements on hard materials, showing hysteresis in the force quadrature curves that we attribute to the finite relaxation time of viscoelastic surface deformation.

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