Performance Evaluation of ANCF Tetrahedral Elements in the Analysis of Liquid Sloshing

2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Dayu Zhang ◽  
Emanuele Grossi ◽  
Ahmed A. Shabana
Keyword(s):  
Element Model ◽  
Solution Procedure ◽  
Liquid Sloshing ◽  
Benchmark Problems ◽  
Numerical Verification ◽  
Tetrahedral Element ◽  
Solid Element ◽  
Tetrahedral Elements ◽  
Curvature Continuity ◽  
Solution Accuracy

Abstract The performance of the absolute nodal coordinate formulation (ANCF) tetrahedral element in the analysis of liquid sloshing is evaluated in this paper using a total Lagrangian nonincremental solution procedure. In this verification study, the results obtained using the ANCF tetrahedral element are compared with the results of the ANCF solid element which has been previously subjected to numerical verification and experimental validation. The tetrahedral-element model, which allows for arbitrarily large displacements including rotations, can be systematically integrated with computational multibody system (MBS) algorithms that allow for developing complex sloshing/vehicle models. The new fluid formulation allows for systematically increasing the degree of continuity in order to obtain higher degree of smoothness at the element interface, eliminate dependent variables, and reduce the model dimensionality. The effect of the fluid/container interaction is examined using a penalty contact approach. Simple benchmark problems and complex railroad vehicle sloshing scenarios are used to examine the performance of the ANCF tetrahedral element in solving liquid sloshing problems. The simulation results show that, unlike the ANCF solid element, the ANCF tetrahedral element model exhibits nonsmoothness of the free surface. This difference is attributed to the gradient discontinuity at the tetrahedral-element interface, use of different meshing rules for the solid- and tetrahedral-elements, and the interaction between elements. It is shown that applying curvature-continuity conditions leads, in general, to higher degree of smoothness. Nonetheless, a higher degree of continuity does not improve the solution accuracy when using the ANCF tetrahedral elements.

scholarly journals Self-updated four-node finite element using deep learning

2021 ◽  
Author(s):  
Jaeho Jung ◽  
Hyungmin Jun ◽  
Phill-Seung Lee
Keyword(s):  
Finite Element ◽  
Deep Learning ◽  
Iterative Solution ◽  
Solution Procedure ◽  
Element Formulation ◽  
Zero Energy ◽  
Energy Mode ◽  
Bending Modes ◽  
Solution Accuracy ◽  
Iterative Solution Procedure

AbstractThis paper introduces a new concept called self-updated finite element (SUFE). The finite element (FE) is activated through an iterative procedure to improve the solution accuracy without mesh refinement. A mode-based finite element formulation is devised for a four-node finite element and the assumed modal strain is employed for bending modes. A search procedure for optimal bending directions is implemented through deep learning for a given element deformation to minimize shear locking. The proposed element is called a self-updated four-node finite element, for which an iterative solution procedure is developed. The element passes the patch and zero-energy mode tests. As the number of iterations increases, the finite element solutions become more and more accurate, resulting in significantly accurate solutions with a few iterations. The SUFE concept is very effective, especially when the meshes are coarse and severely distorted. Its excellent performance is demonstrated through various numerical examples.

scholarly journals Long-Term Vibration Monitoring of the Effects of Temperature and Humidity on PC Girders with and without Fly Ash considering ASR Deterioration

2017 ◽  
Vol 2017 ◽  
pp. 1-23
Author(s):  
Tuan Minh Ha ◽  
Saiji Fukada ◽  
Kazuyuki Torii
Keyword(s):  
Fly Ash ◽  
Prestressed Concrete ◽  
Weather Conditions ◽  
Element Model ◽  
Vibration Monitoring ◽  
Mode Shapes ◽  
Numerical Verification ◽  
Evaluation Procedures ◽  
Temperature And Humidity ◽  
Vibration Responses

Structural responses have been used as inputs in the evaluation procedures of civil structures for years. Apart from the degradation of a structure itself, changes in the environmental conditions affect its characteristics. For adequate maintenance, it is necessary to quantify the environment-induced changes and discriminate them from the effects due to damage. This study investigates the variation in the vibration responses of prestressed concrete (PC) girders, which were deteriorated because of the alkali–silica reaction (ASR), concerning ambient temperature and humidity. Three PC girders were exposed to outdoor weather conditions outside the laboratory, one of which had a selected amount of fly ash in its mixture to mitigate the ASR. The girders were periodically vibration tested for one and a half years. It was found that when the temperature and humidity increased, the frequencies and damping ratios decreased in proportion. No apparent variation in the mode shapes could be identified. A finite element model was proposed for numerical verification, the results of which were in good agreement with the measured changes in the natural frequencies. Moreover, the different dynamic performances of the three specimens indicated that the fly ash significantly affected the vibrations of the PC girders under ASR deterioration.

scholarly journals Study on liquid sloshing characteristics of a swaying rectangular tank with a rolling baffle

2019 ◽  
Vol 119 (1) ◽  
pp. 23-41 ◽  
Author(s):  
Jing-Han Wang ◽  
Shi-Li Sun
Keyword(s):  
Free Surface ◽  
Present Method ◽  
Velocity Potential ◽  
Solution Procedure ◽  
Liquid Sloshing ◽  
Published Data ◽  
Free Surface Elevation ◽  
Separate Variable ◽  
Rectangular Tank ◽  
Vertical Baffle

Abstract This study addresses the sloshing characteristics of a liquid contained in a tank with a vertical baffle mounted at the bottom of the tank. Liquid sloshing characteristics are studied through an analytical solution procedure based on the linear velocity potential theory. The tank is forced to sway horizontally and periodically, while the baffle is fixed to the tank or rolling around a hinged point. The rectangular tank flow field is divided into a few sub-domains. The potentials are solved by a separate variable method, and the boundary conditions and matching requirements between adjacent sub-domains are used to determine the sole solution. The free surface elevations with no baffle or a low fixed baffle are compared with those in published data, and the correctness and reliability of the present method are verified. Then the baffle is forced to rotate around the bottom-mounted point. It is found that the baffle’s motion, including the magnitude and the phase together, can be adjusted to suppress the free surface elevation, and even the sloshing wave can be almost eliminated.

Vibration of Plate Structures Solved by DQEM Using EDQ

2003 ◽  
Author(s):  
Chang-New Chen
Keyword(s):  
Numerical Algorithms ◽  
Element Model ◽  
Equation System ◽  
Solution Procedure ◽  
Analysis Model ◽  
Engineering Structures ◽  
Discrete Eigenvalue ◽  
Plate Structures ◽  
Wide Range ◽  
Structural Boundary

The vibration of plate structures is solved by DQEM using EDQ. In the DQEM discretization, EDQ is used to define the discrete element model. Discrete eigenvalue equations defined at interior discrete points in all elements, transition conditions defined on the inter-element boundary of two adjacent elements and boundary conditions at the structural boundary form the overall discrete eigenvalue equation system. Numerical results obtained by the developed numerical algorithms are presented. They demonstrate the developed numerical solution procedure. This vibration analysis model can be used to solve wide range of offshore engineering structures.

A Computational Method for Stress Analysis of Adaptive Elastic Materials With a View Toward Applications in Strain-Induced Bone Remodeling

1984 ◽  
Vol 106 (4) ◽  
pp. 342-350 ◽  
Author(s):  
R. T. Hart ◽  
D. T. Davy ◽  
K. G. Heiple
Keyword(s):  
Stress Analysis ◽  
Local Strain ◽  
Element Model ◽  
Solution Procedure ◽  
Computational Method ◽  
Long Bone ◽  
Continuum Models ◽  
Elastic Materials ◽  
3 Dimensional ◽  
Dimensional Finite Element

A computational method has been developed to obtain numerical results in the stress analysis of adaptive elastic materials. The method is based on a 3-dimensional finite element model that can change geometry and material properties based on the local strain. The solution procedure is iterative; the model is updated in time steps based on the current remodeling to provide incremental remodeling predictions. The method provides a vehicle for examination of different continuum models and their corresponding parameters for strain-induced remodeling in long bone. Use of the method with simple models of theoretical interest is presented. Results show agreement with available analytical results as well as the importance of coupled remodeling effects not previously examined.

Shock Response Analysis of Marine Gearbox

2014 ◽  
Vol 983 ◽  
pp. 400-403
Author(s):  
Wen Liu ◽  
Teng Jiao Lin ◽  
Ze Yin He
Keyword(s):  
Dynamic Stress ◽  
Strength Criterion ◽  
Element Model ◽  
Vibration Velocity ◽  
Response Analysis ◽  
Tetrahedral Element ◽  
Dynamic Finite Element ◽  
Spring Element ◽  
Equivalent Time ◽  
Shock Response

The shock spectrum of gearbox was gotten according to German specification. And the equivalent time-domain acceleration curve was converted from shock spectrum. After the dynamic finite element model of entire gearbox was established by using the truss element, spring element and tetrahedral element, the shock response including the vibration velocity, acceleration and dynamic stress of gearbox subjected to the acceleration shock excitation were simulated. At last, the anti-shock performance of gearbox was analyzed combining with the strength criterion.

Seismo-Acoustic Benchmark Problems Involving Sloping Solid–Solid Interfaces and Variable Topography

2016 ◽  
Vol 24 (03) ◽  
pp. 1650019 ◽  
Author(s):  
Katherine Woolfe ◽  
Michael D. Collins ◽  
David C. Calvo ◽  
William L. Siegmann
Keyword(s):  
Finite Element ◽  
Wave Equation ◽  
Parabolic Equation ◽  
Finite Element Model ◽  
Element Model ◽  
Single Scattering ◽  
Benchmark Problems ◽  
Scattering Approximation ◽  
Single Scattering Approximation ◽  
Variable Topography

The accuracy of the seismo-acoustic parabolic equation is tested for problems involving sloping solid–solid interfaces and variable topography. The approach involves approximating the medium in terms of a series of range-independent regions, using a parabolic wave equation to propagate the field through each region, and applying a single-scattering approximation to obtain transmitted fields across the vertical interfaces between regions. The accuracy of the parabolic equation method for range-dependent problems in seismo-acoustics was previously tested in the small slope limit. It is tested here for problems involving larger slopes using a finite-element model to generate reference solutions.

Modal Analysis and Experimental Research of Marine Gearbox

2014 ◽  
Vol 607 ◽  
pp. 405-408 ◽  
Author(s):  
Wen Liu ◽  
Teng Jiao Lin ◽  
Quan Cheng Peng
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Modal Analysis ◽  
Experimental Research ◽  
Natural Frequencies ◽  
Element Model ◽  
Ansys Software ◽  
Tetrahedral Element ◽  
Spring Element ◽  
Good Agreement

The gear-shaft-bearing-housing coupled finite element model of marine gearbox was established by using the truss element, the spring element and the tetrahedral element. The modal of gearbox was analyzed by using the ANSYS software. Then through the experimental modal analysis, the natural frequencies of gearbox are obtained. Compare the experimental results with the numerical results, it shows good agreement.

scholarly journals A study on spring-back in U-draw bending of DP350 high-strength steel sheets based on combined isotropic and kinematic hardening laws

2018 ◽  
Vol 10 (9) ◽  
pp. 168781401879743 ◽  
Author(s):  
Van-Canh Tong ◽  
Duc-Toan Nguyen
Keyword(s):  
Process Parameters ◽  
High Strength Steel ◽  
Numerical Models ◽  
Kinematic Hardening ◽  
High Strength ◽  
Transient Behavior ◽  
Element Model ◽  
Benchmark Problems ◽  
Spring Back ◽  
Draw Bending

In this article, a numerical model for predicting spring-back in U-draw bending of DP350 high-strength steel sheet was presented. First, the hardening models were formulated based on combined isotropic–kinematic hardening laws, along with the traditional pure isotropic and kinematic hardening laws. A simplified method was proposed for determining the material parameters. Comparison of stress–strain curves of uniaxial tests at various pre-strains predicted by the numerical models and experiment showed that the combined isotropic–kinematic hardening model could accurately describe the Bauschinger effect and transient behavior subjected to cyclic loading conditions. Then, a finite element model was created to simulate the U-draw bending process using ABAQUS. Simulations were then conducted to predict the spring-back of DP350 high-strength steel in U-draw bending with geometry provided in the NUMISHEET’2011 benchmark problems. It was shown that the predictions of spring-back using the proposed model were in good agreement with the experimental results available in the literature. Finally, the effects of various tool and process parameters such as punch profile radius, die profile radius, blank holding force, and punch-to-die clearance on the spring-back were investigated. The simulation results suggested the significance of tool and process parameters on the final shape of the formed parts influenced by the spring-back.

Nonlinear Analysis of Transmission Tower Structure by Three FEM Models

2011 ◽  
Vol 128-129 ◽  
pp. 914-917
Author(s):  
Wei Yi ◽  
Xiao Hu Liu
Keyword(s):  
Element Model ◽  
Beam Element ◽  
Transmission Tower ◽  
Solid Element ◽  
Truss Element ◽  
Mixed Beam ◽  
Scale Field ◽  
Tower Structure ◽  
Abaqus Software ◽  
Key Nodes

In this paper, three kinds of FEM models, i.e., the truss element model, the beam element model and the mixed beam-solid element model are utilized to simulate the full-scale field test of transmission tower. Based on Abaqus software, the geometric and material nonlinearity of the structure is considered. Comparing the numerical results with test data, it is found that the truss element model is no longer suitable and the mixed beam-solid element model is more accurate than the beam element model. Thus, using solid element to discrete the key nodes of the tower can greatly enhance the accuracy and reliability of the numerical prediction.

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