scholarly journals Combining Finite Element and Analytical methods to Contact Problems of 3D Structure on Soft Foundation

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Chao Su ◽  
Heng Zhang ◽  
Shaopei Hu ◽  
Jiawei Bai ◽  
Jianjian Dai
Keyword(s):  
Finite Element ◽  
3D Structure ◽  
Contact Problems ◽  
Contact Forces ◽  
Structural Deformation ◽  
The Finite Element Method ◽  
Equilibrium Equations ◽  
Soft Foundation ◽  
Rigid Body Displacement ◽  
Finite Method

The computational efficiency and nonconvergence of the iteration are two main difficulties in contact problems, especially in the creep of the foundation. This paper proposes a method to analyze the structural soft foundation system affected by time. The methodology is an explicit method, combining the finite element method with the analytical method. The creep deformation of soft foundation is obtained based on Laplace transforms. The structural deformation contains the statically determinate structural deformation and rigid body displacement, solved by the finite method. The contact forces are calculated by the deformation coordination equations and equilibrium equations. The methodology is validated through augmented Lagrangian (AL) method. The results can clearly illustrate the local disengagement phenome, greatly overcome the nonconvergence of the iteration, and significantly improve computing efficiency.

A Novel Force Sensor Based Multi-Function Take-Off Board

2012 ◽  
Vol 468-471 ◽  
pp. 221-224
Author(s):  
Pei Chen ◽  
Yu Long Zhao ◽  
Bao Jin Wang ◽  
Shan Ping Chen ◽  
Zhen Long Yan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Force Sensor ◽  
Structural Deformation ◽  
Force Sensors ◽  
The Finite Element Method ◽  
Working Mechanism ◽  
Practical Applications ◽  
Jump Training ◽  
Long Jump

In order to detect the take-off forces of athletes in long jump, a novel force sensor based take-off board is designed. The take-off board consists of a standard take-off board, two novel force sensors, two support plates and a base. The working mechanism of the strain beam in the force sensor is analyzed and the finite element method(FEM) is used to investigate the structural deformation and stress distribution. Then the sensor is tested. The calibration experimental results demonstrate that the sensor has an excellent measurement linearity (0.6%) and can meet the requirements of practical applications. Then the multi-function take-off board based on the force sensors is designed and manufactured which can make the daily long jump training more scientific.

On the Unsymmetric Eigenproblem for the Buckling of Shells Under Pressure Loading

1983 ◽  
Vol 50 (1) ◽  
pp. 95-100 ◽  
Author(s):  
H. A. Mang ◽  
R. H. Gallagher
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Hydrostatic Pressure ◽  
Stiffness Matrix ◽  
Circular Cylindrical Shell ◽  
The Finite Element Method ◽  
Equilibrium Equations ◽  
Buckling Loads ◽  
Large Rotations ◽  
Element Method

Consideration of the dependence of hydrostatic pressure on the displacements may result in significant changes of calculated buckling loads of thin arches and shells in comparison with loads calculated without consideration of this effect. The finite element method has made it possible to quantify these changes. On the basis of a shell theory of small displacements but moderately large rotations, this paper derives consistent incremental equilibrium equations for tracing, via the finite element method, the load-displacement path for thin shells subjected to nonuniform hydrostatic pressure and establishes the buckling condition from the incremental equilibrium equations. Within the framework of the finite element method, the character of hydrostatic pressure as one of a follower load is represented in the so-called pressure-stiffness matrix. For shells with loaded free edges, this matrix is unsymmetric. The principal objective of the present paper is to demonstrate that symmetrization of the pressure stiffness matrix resulting from linearization of the buckling condition yields buckling loads that are identical to the eigenvalues resulting from first-order perturbation analysis of the unsymmetric eigenproblem. A circular cylindrical shell with a free and a hinged end, subjected to hydrostatic pressure, is used as an example of the admissibility of symmetrizing the pressure stiffness matrix and for assessing its effect.

Comparison of calculation methods for wheel–switch rail normal and tangential contact

2016 ◽  
Vol 231 (2) ◽  
pp. 148-161 ◽  
Author(s):  
Jingmang Xu ◽  
Ping Wang ◽  
Xiaochuan Ma ◽  
Jieling Xiao ◽  
Rong Chen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Contact Problems ◽  
Rolling Contact ◽  
The Finite Element Method ◽  
Normal Contact ◽  
Tangential Contact ◽  
Contact Models ◽  
Railway Turnout ◽  
Element Method

Wheel–rail contact is more complex in railway a turnout than in ordinary track and, thus, necessitates an advanced model to simulate dynamic interaction and predict rail wear. The main aim of the present work is to assess the application of several wheel–rail rolling contact models in railway turnout. For normal contact problems, wheel–rail contact models based on four different methods are compared: Hertz theory, the semi-Hertzian method, CONTACT, and the finite element method. The assessment is based on the results of contact patch shape and size and contact pressure for several wheelset lateral displacements. The load is set to a constant and equal to static wheel load. Calculations are performed at the section of switch rail head with width 35 mm in CN60-1100-1:18 turnout; both standard and worn rail profiles are accounted for. For tangential contact problems, four corresponding methods are assessed, based on the calculation of creep forces, distribution of the stick/slide region and computational efficiency: Shen–Hedrick–Elkins theory, FASTSIM, improved FASTSIM based on semi-Hertzian method, and CONTACT. It is found that the normal contact problems solved by the semi-Hertzian method and CONTACT correlate well with the finite element method, and the tangential contact problems solved by improved FASTSIM and CONTACT are quite favorable. The conclusions of this work can provide some guidance for contact model selection in the dynamic simulation and wear prediction of railway turnout.

Numerical Simulation of Ship Collision With Gravity Base Foundations of Offshore Wind Turbines

2013 ◽  
Author(s):  
Thorben Hamann ◽  
Torben Pichler ◽  
Jürgen Grabe
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Cost Effective ◽  
Offshore Structures ◽  
Contact Forces ◽  
Offshore Wind ◽  
The Finite Element Method ◽  
Effective Manner ◽  
Ship Collision ◽  
Element Method

For the installation of offshore foundations several countries (e.g. Germany) require a proof of averting environmental disasters in case of ship collision. The aim is to prevent possible discharge of supplies or even loss of the vessel. Especially for gravity base foundations this load case is problematic due to their larger stiffness and mass compared to monopiles, tripods or jacket foundations. The finite element method provides a powerful tool to predict the collision behaviour in a realistic way taking into account the complex interaction between vessel, foundation and soil. The collision between a fully loaded single hull tanker and a gravity base foundation is subject of numerical analysis. The calculated contact forces between vessel and foundation are compared to a simplified calculation approach. For evaluation of the foundation deformations and areas of failure of the vessel are investigated. The influence of the water depth, the diameter of the foundation and an embedment in the seabed are determined in a parametric study. It can be shown that the finite element method is a suitable approach for investigation of the collision behaviour of offshore structures. The design of gravity base foundations can be optimized with respect to ship collision in a fast and cost-effective manner using this method.

The Multi-Deformable Contact Analysis of Rotate Test Tree

2012 ◽  
Vol 562-564 ◽  
pp. 1327-1331
Author(s):  
Jing Hua Liu ◽  
Gui Chuan Hu ◽  
You Qing Ding
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Contact Mechanics ◽  
Lagrange Multiplier ◽  
Contact Force ◽  
Contact Problems ◽  
The Finite Element Method ◽  
Distribution Rules ◽  
Test Tree ◽  
Element Method

In order to research contact force between mechanical components of the multi-deformable assembly and product’s reliability, this paper explored the non-linear contact problems by employing the contact mechanics and the finite element method. On the basis of the Lagrange multiplier algorithm, taking multi-deformable assembly as a system, the finite element method is utilized in this paper to analyze the contact cases among deformable components in various conditions, the distribution rules of contact force, the distribution rules of stress and the deformation, with the purpose of figuring out the weakness regions and their solutions.

scholarly journals Mixed Finite Element Method for Static and Dynamic Contact Problems with Friction and Initial Gaps

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Lanhao Zhao ◽  
Zhi Liu ◽  
Tongchun Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Mixed Finite Element ◽  
Iteration Process ◽  
Mixed Finite Element Method ◽  
Contact Problems ◽  
Dynamic Contact ◽  
Contact Forces ◽  
Stick Slip ◽  
Element Method

A novel mixed finite element method is proposed for static and dynamic contact problems with friction and initial gaps. Based on the characteristic of local nonlinearity for the problem, the system of forces acting on the contactor is divided into two parts: external forces and contact forces. The displacement of structure is chosen as the basic variable and the nodal contact force in contact region under local coordinate system is selected as the iteration variable to confine the nonlinear iteration process in the potential contact surface which is more numerically efficient. In this way, the sophisticated contact nonlinearity is revealed by the variety of the contact forces which are determined by the external load and the contact state stick, slip, or separation. Moreover, in the case of multibody contact problem, the flexibility matrix is symmetric and sparse; thus, the iterative procedure becomes easily carried out and much more economical. In the paper, both the finite element formulations and the iteration process are given in detail for static and dynamic contact problems. Four examples are included to demonstrate the accuracy and applicability of the presented method.

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