Numerical Simulations Concerning the Tendency of Soil Plugging in Open-Ended Steel-Piles

2009 ◽  
Author(s):  
Sascha Henke ◽  
Ju¨rgen Grabe
Keyword(s):  
Finite Element Method ◽  
Granular Soil ◽  
Soil Density ◽  
Soil Plug ◽  
Pile Installation ◽  
Pile Diameter ◽  
Rigid Pile ◽  
Steel Piles ◽  
Plug Formation

The development of soil plug inside open-ended steel-piles is investigated using Finite-Element method. The penetration of a rigid pile with various diameter into granular soil is simulated numerically to better understand the mechanisms which occur during pile installation inside the open-ended piles. The numerical results are analyzed for a better understanding of the influence of the installation method on soil plugging. The received results are compared to experimental results out of literature. Concluding, a parametric study is fulfilled to examine the role of soil density and pile diameter concerning the tendency of plug formation inside a jacked pile.

Large Deformation Numerical Simulations Regarding Soil Plugging Behaviour Inside Open-Ended Piles

2012 ◽  
Author(s):  
Sascha Henke
Keyword(s):  
Numerical Models ◽  
Soil Plug ◽  
Factors Affecting ◽  
Pile Installation ◽  
Pile Diameter ◽  
Key Factor ◽  
Vertical Bearing ◽  
The One ◽  
Plug Formation ◽  
The Impact

Soil-plugging inside open-ended piles is a well-known phenomenon which increases vertical bearing capacity on the one hand but also leads to increasing driving resistance. There are many different factors affecting the tendency of soil-plug formation like pile diameter, geometry of the pile, installation method, soil density and so on. With the basis of experimental data numerical models to simulate the pile installation process to better understand the mechanisms of soil plugging inside open-ended piles are validated. The validated numerical models are used to examine different aspects regarding the phenomenon of soil plug formation. First, the evolution of internal and external shaft friction is investigated in more detail with focus on pile diameter. Furthermore, the impact of internal reinforcements like internal rings are investigated numerically. The shape of the internal ring is varied throughout this study to evaluate the influence of this key factor on internal stress development.

Haemostatic Platelet Plug Formation in the Isolated Rabbit Mesenteric Preparation - An Analysis of Red Blood Cell Participation

1980 ◽  
Vol 44 (01) ◽  
pp. 006-008 ◽  
Author(s):  
D Bergqvist ◽  
K-E Arfors
Keyword(s):  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
In Vitro Test ◽  
Pharmacological Agents ◽  
Vitro Test ◽  
Releasing Effect ◽  
Plug Formation

SummaryIn a model using an isolated rabbit mesenteric preparation microvessels were transected and the time until haemostatic plugs formed was registered. Perfusion of platelet rich plasma gave no haemostasis whereas whole blood did. Addition of chlorpromazine or adenosine to the whole blood significantly prolonged the time for haemostasis, and addition of ADP to the platelet rich plasma significantly shortened it. It is concluded that red cells are necessary for a normal haemostasis in this model, probably by a combination of a haemodynamic and ADP releasing effect.The fundamental role of platelets in haemostatic plug formation is unquestionable but there are still problems concerning the stimulus for this process to start. Three platelet aggregating substances have been discussed – thrombin, adenosine diphosphate (ADP) and collagen. Evidence speaking in favour of thrombin is, however, very minimal, and the discussion has to be focused on collagen and ADP. In an in vitro system using polyethylene tubings we have shown that "haemostasis" can be obtained without the presence of collagen but against these results can be argued that it is only another in vitro test for platelet aggregation (1).To be able to induce haemostasis in this model, however, the presence of red blood cells is necessary. To further study this problem we have developed a model where haemostatic plug formation can be studied in the isolated rabbit mesentery and we have briefly reported on this (2).Thus, it is possible to perfuse the vessels with whole blood as well as with platelet rich plasma (PRP) and different pharmacological agents of importance.

THE ROLE OF FINITE ELEMENT METHOD IN CIVIL ENGINEERING

2018 ◽  
Vol 5 (02) ◽  
Author(s):  
Er. Hardik Dhull
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Approximate Solution ◽  
Analytical Method ◽  
Civil Engineering ◽  
The Finite Element Method ◽  
Engineering Problems ◽  
Building Components ◽  
Element Method

The finite element method is a numerical method that is used to find solution of mathematical and engineering problems. It basically deals with partial differential equations. It is very complex for civil engineers to study various structures by using analytical method,so they prefer finite element methods over the analytical methods. As it is an approximate solution, therefore several limitationsare associated in the applicationsin civil engineering due to misinterpretationof analyst. Hence, the main aim of the paper is to study the finite element method in details along with the benefits and limitations of using this method in analysis of building components like beams, frames, trusses, slabs etc.

scholarly journals An Extended Finite Element Method (XFEM) Study on the Elastic T-Stress Evaluations for a Notch in a Pipe Steel Exposed to Internal Pressure

Mathematics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 507
Author(s):  
K. Yakoubi ◽  
S. Montassir ◽  
Hassane Moustabchir ◽  
A. Elkhalfi ◽  
Catalin Iulian Pruncu ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Internal Pressure ◽  
Extended Finite Element Method ◽  
Research Study ◽  
Extended Finite Element ◽  
T Stress ◽  
Cracked Structures ◽  
Element Method

The work investigates the importance of the K-T approach in the modelling of pressure cracked structures. T-stress is the constant in the second term of the Williams expression; it is often negligible, but recent literature has shown that there are cases where T-stress plays the role of opening the crack, also T-stress improves elastic modeling at the point of crack. In this research study, the most important effects of the T-stress are collected and analyzed. A numerical analysis was carried out by the extended finite element method (X-FEM) to analyze T-stress in an arc with external notch under internal pressure. The different stress method (SDM) is employed to calculate T-stress. Moreover, the influence of the geometry of the notch on the biaxiality is also examined. The biaxiality gave us a view on the initiation of the crack. The results are extended with a comparison to previous literature to validate the promising investigations.

The Qualification of Safety Critical Structures by Finite Element Analytical Methods

1996 ◽  
Vol 210 (2) ◽  
pp. 203-207 ◽  
Author(s):  
A J Morris
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Error Control ◽  
Analysis Method ◽  
The Finite Element Method ◽  
Method Error ◽  
Safety Critical ◽  
Critical Situation ◽  
Error Treatment

The paper introduces the concept of certifying or qualifying structures in a safety critical situation using the finite element method. Error control and error treatment methods for this purpose are discussed together with the associated role of testing. The underlying methodology follows the principles laid down in the SAFESA (SAFE Structural Analysis) method which is described in outline.

scholarly journals Design of Soft Grippers with Modular Actuated Embedded Constraints

Robotics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 105
Author(s):  
Gabriele Maria Achilli ◽  
Maria Cristina Valigi ◽  
Gionata Salvietti ◽  
Monica Malvezzi
Keyword(s):  
Finite Element Method ◽  
Flat Surface ◽  
Thermoplastic Polyurethane ◽  
Fem Analysis ◽  
Robotic Hand ◽  
Main Design ◽  
Grasping And Manipulation ◽  
Static Simulation

Underactuated, modular and compliant hands and grippers are interesting solutions in grasping and manipulation tasks due to their robustness, versatility, and adaptability to uncertainties. However, this type of robotic hand does not usually have enough dexterity in grasping. The implementation of some specific features that can be represented as “embedded constraints” allows to reduce uncertainty and to exploit the role of the environment during the grasp. An example that has these characteristics is the Soft ScoopGripper a gripper that has a rigid flat surface in addition to a pair of modular fingers. In this paper, we propose an upgraded version of the Soft ScoopGripper, developed starting from the limits shown by the starting device. The new design exploits a modular structure to increase the adaptability to the shape of the objects that have to be grasped. In the proposed device the embedded constraint is no rigid neither unactuated and is composed of an alternation of rigid and soft modules, which increase versatility. Moreover, the use of soft material such as thermoplastic polyurethane (TPU) reduces the risk of damage to the object being grasped. In the paper, the main design choices have been exploited and a finite element method (FEM) analysis through static simulation supports a characterization of the proposed solution. A complete prototype and some preliminary tests have been presented.

Torsional complex impedance of pipe pile considering pile installation and soil plug effect

2020 ◽  
Vol 131 ◽  
pp. 106010 ◽  
Author(s):  
Yunpeng Zhang ◽  
Xiaoyan Yang ◽  
Wenbing Wu ◽  
M. Hesham El Naggar ◽  
Guosheng Jiang ◽  
...  
Keyword(s):  
Complex Impedance ◽  
Soil Plug ◽  
Pipe Pile ◽  
Pile Installation

Study on Pile-Soil Interaction during Pile Sinking and Drivability of Pile in Offshore Platform

2012 ◽  
Vol 164 ◽  
pp. 137-141
Author(s):  
Yu Peng Song ◽  
Yong Fu Sun ◽  
Cheng Lin Cao ◽  
Shu Ling Li
Keyword(s):  
Bohai Sea ◽  
Influence Factors ◽  
Penetration Resistance ◽  
Offshore Platform ◽  
Pile Driving ◽  
Main Mode ◽  
Jacket Platform ◽  
Soil Plug ◽  
Steel Piles

The main mode of pile-soil interaction and the influence factors of pile sinking in offshore platform construction were analyzed and discusses the reasons that penetration resistance increases after stop driving and then continue. To study the drivability of piles of specified driving hammer, taking a jacket platform of Bohai Sea for instance, the results showed that continuous driving will make the open-end steel piles be driven to the designed depth, and driven-on will cause soil plug and pile driving refusal. Based on the results, the paper gives some suggestions about pile driving.

Mechanism of platelet plug formation and role of adenosine diphosphate

1964 ◽  
Vol 206 (6) ◽  
pp. 1267-1274 ◽  
Author(s):  
Theodore H. Spaet ◽  
Marjorie B. Zucker
Keyword(s):  
Connective Tissue ◽  
Divalent Cation ◽  
Platelet Rich Plasma ◽  
Adenine Nucleotides ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Suitable Model ◽  
Plug Formation ◽  
Rat Platelets

Traumatized rat omentum was used to demonstrate the development of "platelet plugs" following agitation in platelet-rich plasma. In the absence of divalent cation there was only platelet adhesion to connective tissue fibers; in the presence of divalent cation masses of platelets formed (cohesion) even in plasma adequately anticoagulated with heparin. Exposure of these platelet masses to thrombin produced greater compactness and stability. Human and rat platelets behaved alike with the traumatized rat omentum; platelets from two patients with von Willebrand's disease gave normal reactions whereas platelets from a patient with thrombasthenia showed adhesion only. Exposure of human platelets to washed connective-tissue fragments or to thrombin elicited clumping accompanied by release of serotonin and of adenine nucleotides (AN) of which about one-third was adenosine diphosphate. Intermediate concentrations of connective tissue and thrombin also caused clumping but no liberation of AN or serotonin. ADP caused intense clumping but failed to liberate serotonin or additional ADP. It is suggested that cohesion reaction is mediated by release of ADP. The traumatized omentum appears to be a suitable model for studying the hemostatic process.

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