scholarly journals Feasibility Study on Tension Estimation Technique for Hanger Cables Using the FE Model-Based System Identification Method

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Kyu-Sik Park ◽  
Taek-Ryong Seong ◽  
Myung-Hyun Noh
Keyword(s):  
Finite Element ◽  
System Identification ◽  
Boundary Conditions ◽  
Natural Frequency ◽  
Inverse Analysis ◽  
Finite Element Models ◽  
Fe Model ◽  
Identification Methods ◽  
System Identification Method ◽  
Model Based

Hanger cables in suspension bridges are partly constrained by horizontal clamps. So, existing tension estimation methods based on a single cable model are prone to higher errors as the cable gets shorter, making it more sensitive to flexural rigidity. Therefore, inverse analysis and system identification methods based on finite element models are suggested recently. In this paper, the applicability of system identification methods is investigated using the hanger cables of Gwang-An bridge. The test results show that the inverse analysis and systemic identification methods based on finite element models are more reliable than the existing string theory and linear regression method for calculating the tension in terms of natural frequency errors. However, the estimation error of tension can be varied according to the accuracy of finite element model in model based methods. In particular, the boundary conditions affect the results more profoundly when the cable gets shorter. Therefore, it is important to identify the boundary conditions through experiment if it is possible. The FE model-based tension estimation method using system identification method can take various boundary conditions into account. Also, since it is not sensitive to the number of natural frequency inputs, the availability of this system is high.

Dynamics Analysis of Refrigeration Compressor Based on Finite Element and Experimental Modes

2012 ◽  
Vol 499 ◽  
pp. 238-242
Author(s):  
Li Zhang ◽  
Hong Wu ◽  
Yan Jue Gong ◽  
Shuo Zhang
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Modal Analysis ◽  
Natural Frequency ◽  
High Precision ◽  
3D Model ◽  
Finite Element Models ◽  
Dynamics Analysis ◽  
Response Characteristics ◽  
Dynamic Response Characteristics

Based on the 3D model of refrigeration's compressor by Pro/E software, the analyses of theoretical and experimental mode are carried out in this paper. The results show that the finite element models of compressor have high precision dynamic response characteristics and the natural frequency of the compressor, based on experimental modal analysis, can be accurately obtained, which will contribute to further dynamic designs of mechanical structures.

SEA model for structural acoustic coupling by means of periodic finite element models of the structural subsystems

2021 ◽  
Vol 263 (1) ◽  
pp. 5301-5309
Author(s):  
Luca Alimonti ◽  
Abderrazak Mejdi ◽  
Andrea Parrinello
Keyword(s):  
Finite Element ◽  
Numerical Approach ◽  
Unit Cell ◽  
Analytical Models ◽  
Finite Element Models ◽  
Fe Model ◽  
Acoustic Coupling ◽  
Representative Unit Cell ◽  
Definition Of ◽  
Acoustic Treatment

Statistical Energy Analysis (SEA) often relies on simplified analytical models to compute the parameters required to build the power balance equations of a coupled vibro-acoustic system. However, the vibro-acoustic of modern structural components, such as thick sandwich composites, ribbed panels, isogrids and metamaterials, is often too complex to be amenable to analytical developments without introducing further approximations. To overcome this limitation, a more general numerical approach is considered. It was shown in previous publications that, under the assumption that the structure is made of repetitions of a representative unit cell, a detailed Finite Element (FE) model of the unit cell can be used within a general and accurate numerical SEA framework. In this work, such framework is extended to account for structural-acoustic coupling. Resonant as well as non-resonant acoustic and structural paths are formulated. The effect of any acoustic treatment applied to coupling areas is considered by means of a Generalized Transfer Matrix (TM) approach. Moreover, the formulation employs a definition of pressure loads based on the wavenumber-frequency spectrum, hence allowing for general sources to be fully represented without simplifications. Validations cases are presented to show the effectiveness and generality of the approach.

scholarly journals Analysis of Timoshenko beam with Koch snowflake cross-section and variable properties in different boundary conditions using finite element method

2021 ◽  
Vol 13 (11) ◽  
pp. 168781402110609
Author(s):  
Hossein Talebi Rostami ◽  
Maryam Fallah Najafabadi ◽  
Davood Domiri Ganji
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Boundary Conditions ◽  
Natural Frequency ◽  
Cross Section ◽  
Timoshenko Beam ◽  
Natural Frequencies ◽  
Variable Properties ◽  
The Third ◽  
Koch Snowflake

This study analyzed a Timoshenko beam with Koch snowflake cross-section in different boundary conditions and for variable properties. The equation of motion was solved by the finite element method and verified by Solidworks simulation in a way that the maximum error was about 2.9% for natural frequencies. Displacement and natural frequency for each case presented and compared to other cases. Significant research achievements illustrate that if we change the Koch snowflake cross-section of the beam from the first iteration to the second, the area and moment of inertia will increase, and we have a 5.2% rise in the first natural frequency. Similarly, by changing the cross-section from the second iteration to the third, a 10.2% growth is observed. Also, the hollow cross-section is considered, which can enlarge the natural frequency by about 26.37% compared to a solid one. Moreover, all the clamped-clamped, hinged-hinged, clamped-free, and free-free boundary conditions have the highest natural frequency for the Timoshenko beam with the third iteration of the Koch snowflake cross-section in solid mode. Finally, examining important physical parameters demonstrates that variable density from a minimum value to the standard value along the beam increases the natural frequencies, while variable elastic modulus decreases it.

Automated Finite Element Analysis of Tree Branches

2017 ◽  
Vol 17 (4) ◽  
Author(s):  
Zahra Shahbazi ◽  
Devon Keane ◽  
Domenick Avanzi ◽  
Lance S. Evans
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Biological Materials ◽  
Finite Element Models ◽  
Fe Model ◽  
Biological Applications ◽  
Efficient Tool ◽  
Element Analysis ◽  
New Process ◽  
Tree Branch

Finite element analysis (FEA) has been one of the successful tools in studying mechanical behavior of biological materials. There are many instances where creating FE models requires extensive time and effort. Such instances include finite element analysis of tree branches with complex geometries and varying mechanical properties. Once a FE model of a tree branch is created, the model is not applicable to another branch, and all the modeling steps must be repeated for each new branch with a different geometry and, in some cases, material. In this paper, we describe a new and novel program “Immediate-TREE” and its associated guided user interface (GUI). This program provides researchers a fast and efficient tool to create finite element analysis of a large variety of tree branches. Immediate-TREE automates the process of creating finite element models with the use of computer-generated Python files. Immediate-TREE uses tree branch data (geometry, mechanical, and material properties) and generates Python files. Files were then run in finite element analysis software (abaqus) to complete the analysis. Immediate-TREE is approximately 240 times faster than creating the same model directly in the FEA software (abaqus). This new process can be used with a large variety of biological applications including analyses of bones, teeth, as well as known biological materials.

Analysis of Collisions of Vehicle and Concrete Barrier on Rural Highways

2011 ◽  
Vol 415-417 ◽  
pp. 2304-2307
Author(s):  
Yu Juan Sun ◽  
Jian Rong ◽  
Yong Gang Tai
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Road Safety ◽  
Finite Element Models ◽  
Collision Process ◽  
Rural Highways ◽  
The Road ◽  
Safety Barrier ◽  
Nonlinear Performance ◽  
Concrete Barrier

A concrete barrier used on rural highways of China was proposed. The crashworthiness of the concrete barrier was analyzed using the non-linear explicit dynamics FE code LS-DYNA. The finite element models of car, bus and concrete barrier were developed and validated using experimental results. These models can be used to simulate the dynamic collision process and evaluate the performance of the road safety barrier on rural highways. The nonlinear performance of materials as well as the boundary conditions was considered. The results show that the concrete barrier could contain and redirect the car and bus in the collision.

scholarly journals Effect of Torsional Element towards High-Speed Rotating Shaft’s Critical Speed at Different Boundary Conditions

2019 ◽  
Vol 8 (4) ◽  
pp. 6787-6792
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
High Speed ◽  
Critical Speed ◽  
Element Model ◽  
Accurate Estimation ◽  
Fe Model ◽  
Rotating Shaft ◽  
Different Boundary Conditions ◽  
The Difference

Efficiency improvement that can be provided by the high-speed rotating equipment becomes a concern for designers nowadays. Since the high-speed rotating machinery was capable of rotating at very near to critical speed, the accurate estimation of critical speed needs to be considered. This paper investigated the effect of torsional element towards critical speed of high-speed rotating shaft system for pinned-pinned (P-P), clamped-free (C-F) and clamped-free (C-F) boundaries condition. The Nelson’s finite element model that considers the torsional effect was developed for formulating the finite element (FE) model. This FE model was used to derive Mathieu-Hill’s equation and then solved by applying the Bolotin’s theory. From the solution, the Campbell’s diagram of the high-speed shaft was plotted. It was found that torsional motion has significant effect on the critical speed for different boundary conditions. The difference between critical speed of 4DOF and 5DOF models can be as high as 6.91 %.

Finite Element Analysis in 3D Using the Penalty Boundary Method

2002 ◽  
Author(s):  
Brett W. Clark ◽  
David C. Anderson
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Boundary Conditions ◽  
Mesh Generation ◽  
Discretization Error ◽  
Finite Element Models ◽  
Element Analysis ◽  
Hexahedral Elements ◽  
Boundary Method ◽  
Time Required

Traditional methods for applying boundary conditions in finite element analysis require the mesh to conform to the geometry boundaries. This in turn requires complex meshing algorithms for automated mesh generation from CAD geometry, particularly when using quadrilateral and hexahedral elements. The 3D extension of the penalty boundary method (PBM) is presented as a method that significantly reduces the time required generating finite element models because the mesh is not required to conform to the CAD geometry. The PBM employs penalty methods to apply boundary conditions on a simple, regular mesh. The PBM also eliminates discretization error because boundary conditions are applied using CAD geometry directly rather than an approximation of the geometry.

Vibro-Acoustic Studies of Transmission Casing Structures

1998 ◽  
Author(s):  
D. Crimaldi ◽  
R. Singh
Keyword(s):  
Finite Element ◽  
Free Boundary ◽  
Boundary Conditions ◽  
Material Properties ◽  
Acoustic Radiation ◽  
Real Life ◽  
Cover Plate ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Free Boundary Conditions

Abstract Automotive transmission casing plates of irregular shape, with complex boundary conditions and non-uniform material properties, are experimentally and computationally studied to acquire a fundamental understanding of their dynamic and acoustic radiation characteristics. A modified flat cover is designed which simplifies the geometry while providing uniform thickness and material properties. Both covers (“real-life” and “laboratory”) are studied with free and bolted boundary conditions. In particular, the free boundary conditions are useful because they eliminate the cover-housing interaction allowing for a more detailed analysis of the cover plate. Finite element models for both covers under the free boundary conditions are developed and refined. Predicted natural frequencies and mode shapes are in excellent agreement with measured modal data. Then the finite element models are coupled with boundary element models to predict acoustic radiation properties. Predictions match well with measured acoustic directivity at resonant frequencies.

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