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.

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

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Yanbing Zhao ◽  
Haixiao Liu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Strain Rate ◽  
Three Dimensional ◽  
Large Strains ◽  
Element Analysis ◽  
Soil Strain ◽  
Deformation Strain Rate ◽  
Key Techniques ◽  
3D Profile

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 deg rotation of the anchor arm, gravity installation of anchors with high soil strain rate, and keying and diving (or penetration) of anchors. The 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 (3D) profile in the soil. Finite element 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. This paper gives an overview of several key techniques in the coupled Eulerian–Lagrangian (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, suction embedded plate anchors (SEPLAs) 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 an effective numerical framework to analyze the comprehensive behaviors of anchor lines and deepwater anchors.

Influence of temperature and strain rate on the longitudinal compressive crashworthiness of 3D braided composite tubes and finite element analysis

2016 ◽  
Vol 26 (7) ◽  
pp. 1003-1027 ◽  
Author(s):  
Xianyan Wu ◽  
Qian Zhang ◽  
Bohong Gu ◽  
Baozhong Sun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Strain Rate ◽  
Coupling Effect ◽  
Three Dimensional ◽  
Composite Tubes ◽  
Element Analysis ◽  
Impact Compression ◽  
Mechanical Coupling ◽  
The Impact

This article reports the longitudinal compressive crashworthiness of three-dimensional four-step circular braided carbon/epoxy composite tubes at temperatures of 23, −50, and −100℃ under strain rate ranging from 340 to 760/s both experimentally and finite element analysis. The experimental results showed that the compression strength, stiffness, and specific energy absorption increased with the decrease in temperature and with the increase in strain rate. It also showed that, the compressive damage morphologies were sensitive to the change in temperature and strain rate. A coupled thermal-mechanical numerical analysis was conducted to find the thermo/mechanical coupling effect on the compressive crashworthiness of the three-dimensional composite tube. The temperature distributions in the braided preform and the resin during the impact compression were also calculated through finite element analysis. From the finite element analysis results, the inelastic heat generation was seen to be more in the preform than the matrix and its distribution and accumulation led to the damage progress along the loading direction.

Investigation of Strain Hardening in NiAl Single Crystals Using Three-Dimensional FEA Models

1999 ◽  
Vol 123 (1) ◽  
pp. 20-27 ◽  
Author(s):  
Chulho Yang ◽  
Ashok V. Kumar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Strain Hardening ◽  
Single Crystals ◽  
Three Dimensional ◽  
High Rate ◽  
Large Strains ◽  
Slip Systems ◽  
Element Analysis ◽  
Hardening Model

Single crystals of NiAl are very ductile at intermediate temperatures (400–700 K) and were observed to exhibit high strain hardening rates at large strains when loaded in the [110] orientation. The experimentally observed strain hardening in NiAl single crystals could not be predicted using simple hardening models and two-dimensional finite element analysis. The primary slip systems that activate during the deformation are (010)[100] and (100)[100], however, it has been hypothesized that activation of secondary slip on {011} slip planes may be responsible for the high rate of hardening observed. The hardening of intermetallic single crystals when multiple slip systems are activated is not well understood. To study this further, a three-dimensional hardening model and constitutive equations were implemented into a finite element analysis program. Since the parameters required to describe the hardening model such as latent hardening ratios are difficult to obtain experimentally, a parametric study was conducted to estimate values for these parameters that enable the prediction of the experimentally observed load versus elongation curves.

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.

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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