Large Deformation Finite Element Analysis of Gravity Installed Anchors in Clay

2014 ◽  
Author(s):  
Jun Liu ◽  
Lihui Lu ◽  
Long Yu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Large Deformation ◽  
Three Dimensional ◽  
Cost Effective ◽  
Test Results ◽  
Pullout Capacity ◽  
Element Analysis ◽  
Floating Structures ◽  
Tetrahedral Elements

The OMNI-Max anchor is a multi-directional, self-inserting, gravity-installed anchor and used as foundation for mooring deep water offshore facilities, including risers and floating structures. The OMNI-Max anchor offers a cost effective anchoring solution with improved reliability in the mooring system. Pullout capacity and keying behavior are two important issues in the design of the OMNI-Max anchor. In this paper, the pullout capacity and the keying process of a vertically installed OMNI-Max anchor embedded in normally consolidated clay were simulated using three dimensional large deformation finite element analysis. In these numerical analyses, 10-node tetrahedral elements were used to predict the collapse loads of undrained geotechnical problems involving material incompressibility. Nodal joint elements were used to simulate the interaction between the anchor and soil. The effect of the loading angle on the keying behavior of the OMNI-Max anchor was considered. The analyses clearly show the two important processes (1) “keying”: the anchor rotates rapidly until reaching the best bearing capacity position; (2) “diving”: the anchor mainly translates with tiny rotation. It agrees well with the keying and diving phenomenon in published model test results.

Key Techniques in Simulating Comprehensive Anchor Behaviors by Large Deformation Finite Element Analysis

2017 ◽  
Author(s):  
Yanbing Zhao ◽  
Haixiao Liu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Strain Rate ◽  
Large Deformation ◽  
Three Dimensional ◽  
Large Strains ◽  
Lagrangian Analysis ◽  
Element Analysis ◽  
Deformation Strain Rate ◽  
Key Techniques

With the application of innovative anchor concepts and advanced technologies in deepwater moorings, anchor behaviors in the seabed are becoming more complicated, such as 360-degree rotation of the anchor arm, gravity installation of anchors with high soil strain rate, and keying and diving (or penetration) of anchors. As a very important component of the installation or mooring system, anchor line connects the anchor and the anchor handling vessel (AHV) or floating moored platform. With moving of the AHV or platform, anchor line produces a space movement, and forms a reverse catenary shape and even a three-dimensional profile in the soil. Numerical analysis on the behaviors of anchor lines and deepwater anchors requires techniques that can deal with large strains and deformations of the soil, track changes in soil strength due to soil deformation, strain rate and strain softening effects, appropriately describe anchor-soil friction, and construct structures with connector elements to conform to their characteristics. Being an effective tool of large deformation finite element analysis, the coupled Eulerian-Lagrangian (CEL) method is advantageous in handling geotechnical problems with large deformations, where a traditional Lagrangian analysis is coupled with an Eulerian phase of material advection. This paper gives an overview of several key techniques in the CEL analysis of comprehensive behaviors of deepwater anchors, including construction of the embedded anchor line and the anchor line in the water, installation of gravity installed anchors (GIAs), keying or diving of drag anchors and GIAs, and implementation of the omni-directional arm of GIAs. Numerical probe tests and comparative studies are also presented to examine the robustness and accuracy of the proposed techniques. The aim of this paper is to provide a numerical framework to analyze the comprehensive behaviors of anchor lines and deepwater anchors.

Numerical Simulation of Drag Anchor Installation by a Large Deformation Finite Element Technique

2014 ◽  
Author(s):  
Yanbing Zhao ◽  
Haixiao Liu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Large Deformation ◽  
Fe Simulation ◽  
Fe Analysis ◽  
Movement Direction ◽  
Pullout Capacity ◽  
Fe Method ◽  
Element Analysis ◽  
Element Technique

Previously published finite element analysis of drag anchors only involved the pullout capacity of the anchor. There are no finite element (FE) simulations of the installation of drag anchors probably because of two restrictions. First, during the anchor installation, the installation line is needed, which is difficult to be simulated in the FE analysis. Second, the anchor installation that involves large deformation of surrounding soils can not be solved using the classical FE method. In the present work, the installation line is constructed by connecting cylindrical units with each other using connector elements. Then it is introduced into the installation of drag anchors, which is simulated by a large deformation finite element analysis using the coupled Eulerian-Lagrangian (CEL) technique. By comparing with theoretical solutions, including the tension and profile of the installation line embedded in soils, and the movement direction, drag force, drag angle and trajectory of the anchor, the FE simulation of the drag anchor installation is well verified. The present study also demonstrates that the CEL technique is effective for simulating the anchor-line-soil interactional problems.

Finite Element Analysis of Nonuniformity of Tires with Imperfections5

2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Radial Force ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Force Variation ◽  
Three Dimensional Finite Element

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.

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