Mesh Convergence Studies for Thin Shell Elements Developed by the ASME Task Group on Computational Modeling

2011 ◽  
Author(s):  
Gordon S. Bjorkman ◽  
David P. Molitoris
Keyword(s):  
Finite Element ◽  
Computational Modeling ◽  
Finite Element Model ◽  
Thin Shell ◽  
Element Model ◽  
Task Group ◽  
Plastic Strains ◽  
Shell Elements ◽  
Explicit Dynamics

The ASME Task Group on Computational Modeling for Explicit Dynamics was founded in August 2008 for the purpose of creating a quantitative guidance document for the development of finite element models used to analyze energy-limited events using explicit dynamics software. This document will be referenced in the ASME Code Section III, Division 3 and the next revision of NRC Regulatory Guide 7.6 as a means by which the quality of a finite element model may be judged. One portion of the document will be devoted to a series of element convergence studies that can aid designers in establishing the mesh refinement requirements necessary to achieve accurate results for a variety of different elements types in regions of high plastic strain. These convergence studies will also aid reviewers in evaluating the quality of a finite element model and the apparent accuracy of its results. In this paper the authors present the results of a convergence study for an impulsively loaded propped cantilever beam constructed of LS-DYNA thin shell elements using both reduced and full integration. Three loading levels are considered; the first maintains strains within the elastic range, the second induces moderate plastic strains, and the third produces large deformations and large plastic strains.

Mesh Convergence Studies for Hexahedral Elements Developed by the ASME Special Working Group on Computational Modeling

2013 ◽  
Author(s):  
Chi-Fung Tso ◽  
David P. Molitoris ◽  
Michael Yaksh ◽  
Spencer Snow ◽  
Doug Ammerman ◽  
...  
Keyword(s):  
Finite Element ◽  
Computational Modeling ◽  
Finite Element Model ◽  
Working Group ◽  
Element Model ◽  
Plastic Strains ◽  
Hexahedral Elements ◽  
Special Working ◽  
Special Working Group

The ASME Special Working Group on Computational Modeling for Explicit Dynamics was founded in August 2008 for the purpose of creating a quantitative guidance document for the development of finite element models used to analyze energy-limited events using explicit dynamics software. This document will be referenced in the ASME Code Section III, Division 3 and the next revision of NRC Regulatory Guide 7.6 as a means by which the quality of a finite element model may be judged. One portion of the document will be devoted to a series of element convergence studies that can aid designers in establishing the mesh refinement requirements necessary to achieve accurate results for a variety of different element types in regions of high plastic strain. These convergence studies will also aid reviewers in evaluating the quality of a finite element model and the apparent accuracy of its results. In this paper, the authors present the results of a convergence study for an impulsively loaded propped cantilever beam constructed of LS-DYNA hexahedral elements using both reduced and selectively reduced integration. Three loading levels are considered; the first maintains strains within the elastic range, the second induces moderate plastic strains, and the third produces large deformations and large plastic strains.

Mesh Convergence Studies for Thick Shell Elements Developed by the ASME Special Working Group on Computational Modeling

2013 ◽  
Author(s):  
David P. Molitoris ◽  
Gordon S. Bjorkman ◽  
Chi-Fung Tso ◽  
Michael Yaksh
Keyword(s):  
Finite Element ◽  
Plastic Strain ◽  
Finite Element Model ◽  
Working Group ◽  
Element Model ◽  
Thick Shell ◽  
Shell Elements ◽  
Special Working ◽  
Special Working Group

The ASME Special Working Group on Computational Modeling for Explicit Dynamics was founded in August 2008 for the purpose of creating a quantitative guidance document for the development of finite element models used to analyze energy-limited events using explicit dynamics software. This document will be referenced in the ASME Code Section III, Division 3 and the next revision of NRC Regulatory Guide 7.6 as a means by which the quality of a finite element model may be judged. One portion of the document will be devoted to a series of element convergence studies that can aid designers in establishing the mesh refinement requirements necessary to achieve accurate results for a variety of different element types in regions of high plastic strain. These convergence studies will also aid reviewers in evaluating the quality of a finite element model and the apparent accuracy of its results. In this paper, the authors present the results of a convergence study for an impulsively loaded propped cantilever beam constructed of LS-DYNA thick shell elements using both reduced and selectively reduced integration. A large load is applied to produce large deformations and large plastic strains in the beam. The deformation and plastic strain results are then compared to similar results obtained using thin shell elements and hexahedral elements for the beam mesh.

Model structure correction and updating of aeroengine casings using fictitious mass modifications

2005 ◽  
Vol 219 (1) ◽  
pp. 19-30 ◽  
Author(s):  
H Shahverdi ◽  
C Mares ◽  
J E Mottershead
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Element Model ◽  
Mode Shapes ◽  
Combined Model ◽  
Shell Elements ◽  
Turbine Casing ◽  
The Finite Element Model

In this paper the results of a finite element model updating exercise, carried out on closely axisymmetric aeroengine casings, are presented. The correction of the combustion chamber outer casing (CCOC) model is considered and, after assembly with the turbine casing (TC), the quality of the resulting combined model is investigated. The dynamics of both casings is characterized by pairs of close modes, which may be separated by fictitious point mass modifications. The natural frequencies and mode shapes of the fictitiously modified CCOC are determined from receptances obtained from the CCOC in its original (unmodified) configuration. The modifications are shown to improve the understanding of both the CCOC and the system formed by connecting the CCOC to the TC. A particular problem is revealed when model updating is applied to the CCOC. An analysis of the mode shapes locates a modelling error on an inner shell of the structure but it is found that the finite element model is unable to be parameterized for the correction of two pairs of wrongly ordered predicted modes. This can only be achieved by firstly correcting the ‘structure’ of the model itself. The main error is found to be a geometrical inaccuracy, and, when this is put right, the sequence of the modes is corrected. Model updating is then applied to the thickness of certain shell elements and the CCOC is found to be in excellent agreement with measured data, as is the complete model formed from the two models of the CCOC and the TC together.

Finite Element Modeling of Unidirectional Non-Crimp Fabric for Manufacturing of Composites with Embedded Cabling

2013 ◽  
Vol 554-557 ◽  
pp. 484-491 ◽  
Author(s):  
Alexander S. Petrov ◽  
James A. Sherwood ◽  
Konstantine A. Fetfatsidis ◽  
Cynthia J. Mitchell
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Explicit Finite Element ◽  
Shell Elements ◽  
Beam Elements ◽  
Hybrid Finite Element ◽  
International Benchmarking ◽  
Unidirectional Glass ◽  
Forming Simulations

A hybrid finite element discrete mesoscopic approach is used to model the forming of composite parts using a unidirectional glass prepreg non-crimp fabric (NCF). The tensile behavior of the fabric is represented using 1-D beam elements, and the shearing behavior is captured using 2-D shell elements into an ABAQUS/Explicit finite element model via a user-defined material subroutine. The forming of a hemisphere is simulated using a finite element model of the fabric, and the results are compared to a thermostamped part as a demonstration of the capabilities of the used methodology. Forming simulations using a double-dome geometry, which has been used in an international benchmarking program, were then performed with the validated finite element model to explore the ability of the unidirectional fabric to accommodate the presence of interlaminate cabling.

The Finite Element Analysis on the Compression Splicing Position of Strain Clamp in Guy Tower

2014 ◽  
Vol 680 ◽  
pp. 249-253
Author(s):  
Zhang Qi Wang ◽  
Jun Li ◽  
Wen Gang Yang ◽  
Yong Feng Cheng
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Finite Element Model ◽  
Equivalent Stress ◽  
Element Model ◽  
Element Analysis ◽  
Elastic Plastic ◽  
The Finite Element Analysis

Strain clamp is an important connection device in guy tower. If the quality of the compression splicing position is unsatisfied, strain clamp tends to be damaged which may lead to the final collapse of a guy tower as well as huge economic lost. In this paper, stress distribution on the compressible tube and guy cable is analyzed by FEM, and a large equivalent stress of guy cable is applied to the compression splicing position. During this process, a finite element model of strain clamp is established for guy cables at compression splicing position, problems of elastic-plastic and contracting are studied and the whole compressing process of compressible position is simulated. The guy cable cracks easily at the position of compressible tube’s port, the inner part of the compressible tube has a larger equivalent stress than outside.

Modal Analysis of BT Spindle-Toolholder Interface Based on Abaqus/Standard

2013 ◽  
Vol 662 ◽  
pp. 632-636
Author(s):  
Yong Sheng Zhao ◽  
Jing Yang ◽  
Xiao Lei Song ◽  
Zi Jun Qi
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Modal Analysis ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Element Model ◽  
Contact Theory ◽  
High Speed Machining ◽  
The Finite Element Model

The quality of high speed machining is directly related to dynamic characteristics of spindle-toolholder interface. The paper established normal and tangential interactions of BT spindle-toolholder interface based on finite element contact theory, and analysed free modal in Abaqus/Standard. Then the result was compared with the experimental modal analysis. It shows that the finite element model is effective and could be applied in the future dynamic study of high-speed spindle system.

Quick Aeromechanical Assessment of Turbine Blades Based on Shell Element Based Models

2014 ◽  
Author(s):  
Suryarghya Chakrabarti ◽  
Letian Wang ◽  
K. M. K. Genghis Khan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Natural Frequencies ◽  
Turbine Blades ◽  
Computation Time ◽  
Shell Element ◽  
Element Model ◽  
Shell Elements ◽  
Barrier Coating ◽  
Order Of Magnitude

A fast finite element model based tool has been developed to calculate the natural frequencies of fundamental modes of cooled gas turbine bladed disk assemblies during conceptual design. The tool uses shell elements to model the airfoil, shank, and disk, and achieves order of magnitude reduction in computation time allowing exploration of a wide design space at the preliminary design stages. The analysis includes prestress effects due to centrifugal loading and approximate temperature loading on the parts. Sensitivity studies are performed to understand the relative impact of design features such as airfoil internal geometry, bond coat, and thermal barrier coating on the system natural frequencies. Critical features are selected which need to be modeled to get an accurate natural frequency estimate. The results obtained are shown to be within 5% of the frequencies obtained from a full-fidelity finite element model. A case study performed on seven blade designs illustrates the use of this tool for quick aeromechanical assessment of a large number of designs.

Seismic analysis of elevated pure conical tanks under vertical excitation

2014 ◽  
Vol 41 (10) ◽  
pp. 909-917 ◽  
Author(s):  
Michael Jolie ◽  
Ayman M. El Ansary ◽  
Ashraf A. El Damatty
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Vertical Component ◽  
Element Model ◽  
Shell Elements ◽  
Vertical Excitation ◽  
Analysis And Design ◽  
Conical Tanks

Truncated conical vessels are commonly used as liquid containers in elevated tanks. Despite the widespread use of this type of structure worldwide, no direct code provisions are currently available covering its seismic analysis and design. The purpose of the current study is to assess the importance of considering the vertical component of ground accelerations when analyzing and designing this type of water-storage structure. The study is conducted using an equivalent mechanical model that estimates the normal forces that develop in the tank walls when subjected to vertical excitation. In addition, a three-dimensional finite element model has been developed by modeling the walls of the tank using shell elements. The finite element model has been employed to predict maximum membrane and overall meridional stresses due to both hydrodynamic and hydrostatic pressure distributions. Comparisons have been conducted to assess the significance of considering vertical excitation and to identify the magnification in meridional stresses due to bending effects associated with support conditions and large deformations.

The Technology of Flexible Blank Holder Forming and the Study of its Numerical Simulation

2014 ◽  
Vol 490-491 ◽  
pp. 776-780
Author(s):  
Lian Cheng Li ◽  
Ming Zhe Li ◽  
Xiao Wei Wang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Thickness Distribution ◽  
Element Model ◽  
Spring Back ◽  
Blank Holder ◽  
Distribution Parameters ◽  
Stress And Strain Distribution ◽  
The Finite Element Model

Abstract. In this paper, we have discussed the principle of the flexible blank holder forming ( FBHF) technology, and established the finite element model of medal deep drawing process based on FBHF. Then we have discussed the FBHF technology by analyzing the system of finite element model. By simulating the forming of rectangular box, we can conclude that FBHF technology will have a greater advantage when the depth of stamping forming is much deeper. We have also compared the thickness distribution parameters, wrinkling parameters, and spring back parameters of rigid blank holder forming parts with FBHF parts. The result shows that the forming parts of FBHF technology has uniform stress and strain distribution, small spring back, the quality of inhibiting wrinkling, crack and other defects.

A Finite Element Model for Thick-Walled Axisymmetric Shells

1982 ◽  
Vol 104 (3) ◽  
pp. 215-222 ◽  
Author(s):  
D. J. Barrett ◽  
A. Soler
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Finite Element Model ◽  
Thin Shell ◽  
Element Model ◽  
Order Theory ◽  
Higher Order ◽  
Shells Of Revolution ◽  
Geometric Conditions ◽  
Higher Order Theory

The symmetrically loaded moderately thick-walled shell of revolution can be treated by general finite elements, or for certain geometric conditions, by extended thin shell finite elements that have incorporated transverse shear deformation. In this work, we develop a higher order theory finite element model for symmetrically loaded shells of revolution which is useful for configurations which are out of the range of validity of the extended thin shell elements. Legendre polynomial series expansions are key features of the development and lead to nonlinear distributions of both stress and deformation in the thickness variable. Problems are solved to yield some initial data for comparison of the cost and accuracy of the higher order theory finite element model to other shell element models.

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