A New Procedure for Structural Fault Estimation Using a Prescribed Eigen-Structure

2015 ◽  
Vol 764-765 ◽  
pp. 1015-1019
Author(s):  
Kun Nan Chen ◽  
Wen Der Ueng ◽  
Yunn Lin Hwang
Keyword(s):  
Finite Element ◽  
Structural Damage ◽  
Degrees Of Freedom ◽  
Fault Estimation ◽  
Computationally Efficient ◽  
Element Analysis ◽  
Stiffness Reduction ◽  
Stiffness Matrices ◽  
The Finite Element Analysis ◽  
Incomplete Measurement

A new method using an incomplete measurement set to locate and identify structural damage is proposed. The method is iterative yet computationally efficient and requires no sensitivity calculations. Mass and stiffness matrices, established by finite element method, are partitioned and measured partial eigenvectors are expanded to full modes. Stiffness reduction coefficients for structural elements are defined and then solved by a nonnegative least-squares solution scheme. With much less measured degrees of freedom and even less measured modes than the finite element analysis degrees of freedom, the proposed approach can still identify the damaged locations and extent of the damage in a structure. The effectiveness of the method is demonstrated by solving a numerically simulated example on the GARTEUR SM-AG19 structure.

Finite Element Quarter Vehicle Suspension Model under Periodic Bump and Sinusoidal Road Excitation

2018 ◽  
Vol 880 ◽  
pp. 163-170
Author(s):  
Ștefan Cristian Castravete ◽  
Gabriel Cătălin Marinescu ◽  
Nicolae Dumitru ◽  
Oana Victoria Oţăt
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Finite Model ◽  
Vehicle Speed ◽  
Element Analysis ◽  
Car Suspension ◽  
The Finite Element Analysis ◽  
Road Excitation ◽  
Suspension Model

The paper studies the behavior of a quarter-car suspension model under periodic road excitation: sinusoidal and bump (trapezoidal shape) for a constant vehicle speed. A theoretical and a finite element model were developed. The theoretical model has two degrees of freedom and a modal and sinusoidal excitation was performed to compare with finite model analysis. The finite element analysis consists of three parts: preload, modal analysis and deterministic external excitation. The study consists of the analysis of forces, displacements and accelerations that are transmitted to the vehicle regarding their variation in time and frequency.

Dynamic Finite Element Analysis of a Highly Parallel Robotic Surface

2011 ◽  
Author(s):  
Chris Salisbury
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Angular Displacement ◽  
Three Dimensional ◽  
Element Analysis ◽  
Revolute Joints ◽  
Stiffness Matrices ◽  
Joint Forces ◽  
Ricatti Equation ◽  
Optimal Dynamic

A novel three-dimensional robotic surface is devised using triangular modules connected by revolute joints that mimic the constraints of a spherical joint at each triangle intersection. The finite element method (FEM) is applied to the dynamic loading of this device using three dimensional (6 degrees of freedom) beam elements to not only calculate the cartesian displacement and force, but also the angular displacement and torque at each joint. In this way, the traditional methods of finding joint forces and torques are completely bypassed. An effiecient algorithm is developed to linearly combine local mass and stiffness matrices into a full structural stiffness matrix for the easy application of loads. An analysis of optimal dynamic joint forces is carried out in Simulink® with the use of an algebraic Ricatti equation.

Workspace Comparison Between 3-PRR and 3-RPR Micro-Manipulator

2012 ◽  
Author(s):  
Yi Dong ◽  
Feng Gao ◽  
Yi Yue ◽  
Jin Feng
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Degrees Of Freedom ◽  
The Other ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Structural Differences ◽  
Micro Manipulator

This paper presents two compliant micro-manipulators with different structures. One uses 3-PRR mechanism while the other one adopts 3-RPR mechanism. Both of the two micro-manipulators have two translational degrees of freedom (DOF) and one rotational DOF. But the properties, such as workspace, of the two micro-manipulators are not the same. In this paper, the workspaces are studied and compared. First, the structural differences are presented. Then, the stiffness derivations of the two micro-manipulators are given and the workspaces are calculated considering the properties of piezoelectric (PZT) actuators. Finally the finite element analysis and prototype experiments are performed to validate the obtained results.

Flexible-Body Dynamics Modelling With a Reduced-Order Model

1990 ◽  
Author(s):  
K. Harold Yae ◽  
Daniel J. Inman
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Reduced Model ◽  
Flexible Body ◽  
State Variables ◽  
Dynamics Modeling ◽  
Element Analysis ◽  
Stiffness Matrices

Abstract In the dynamics modeling of a flexible body, finite element analysis employs Guyan’s reduction that removes some of the “insignificant” physical coordinates, thus producing a dynamic model that has smaller mass and stiffness matrices. Despite such reduction, the resultant model is still too large for flexible-body dynamic analysis. That warrants further reduction as is frequently used in control design by approximating a large dynamical system with a fewer number of state variables. When the reduced model is being assembled with other bodies in a multi-body mechanism, a problem, however, arises because a model usually undergoes, before being reduced, some form of coordinate transformations that do not preserve the physical meanings of the states. To correct such a problem, we developed a method that expresses a reduced model in terms of a subset of the original states. The proposed method starts with a dynamic model that is originated and reduced in finite element analysis. Then the model is converted to the state space form, and reduced again by the internal balancing method. At this stage, being in the balanced coordinate system, the states in the reduced model have no apparent resemblance to those of the original model. Through another coordinate transformation that is developed in this paper, however, this reduced model is expressed by a subset of the original states. Then finally the model can be represented by the states assigned to the degrees of freedom of the selected nodal points.

Deep Drawing of Square-Shaped Sheet Metal Parts, Part 1: Finite Element Analysis

1993 ◽  
Vol 115 (1) ◽  
pp. 102-109 ◽  
Author(s):  
S. A. Majlessi ◽  
D. Lee
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Membrane Properties ◽  
Computationally Efficient ◽  
Element Analysis ◽  
Sheet Metal Parts ◽  
Part Geometry ◽  
Analysis Technique ◽  
The Finite Element Analysis ◽  
Good Agreement

The process of square-cup drawing is modeled employing a simplified finite element analysis technique. In order to make the algorithm computationally efficient, the deformation (total strain) theory of plasticity is adopted. The solution scheme is comprised of specifying a mesh of two-dimensional finite elements with membrane properties over the deformed configuration of the final part geometry. The initial positions of these elements are then computed by minimization of the potential energy, and therefore the strain distributions are determined. In order to verify predictions made by the finite element analysis method, a drawing apparatus is built and various drawing experiments are carried out. A number of circular and square cups are drawn and strain distributions measured. It is observed that there is generally a good agreement between computed and measured results for both axisymmetric and nonaxisymmetric cases.

Stability of mirror chambers and mechanics: an example of the improvement of vibrational behaviour

2010 ◽  
Vol 1 (MEDSI-6) ◽  
Author(s):  
C. Ruget ◽  
L. Nikitina ◽  
J. Nicolas ◽  
J.C. Martinez ◽  
J. Juanhuix
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Degrees Of Freedom ◽  
High Stability ◽  
Element Analysis ◽  
Detailed Design ◽  
The Finite Element Analysis ◽  
Synchrotron Light ◽  
High Level ◽  
Low Emittance

ALBA synchrotron light facility includes a 3 GeV low-emittance storage ring capable of running in the top-up mode which will feed a number of beamlines. Xaloc and CIRCE are among these beamlines. These beamlines are equipped with mirrors which need high stability. There are a lot of mirror chambers in the market and we decided to improve one of them rather than developing a new one. For this purpose, the ALBA team organized a collaboration with a supplier of beamline components. ALBA did the conceptual design of the improvements, the Finite Element Analysis (FEA) optimization and the metrology tests. The supplier provided a detailed design and the production. The improvement was implemented on several mirror chambers including actuators from two to five degrees of freedom. At the beginning of the project, the hypothesis was an excitation coming from the ground lower than 1 µm for frequencies below 45 Hz and negligible above it. The strategy[0] in terms of dynamical stability was not to amplify the ground excitation below 45 Hz or around 50 Hz. That is, to increase the frequency of the system resonances above 45 Hz (excluding the range of about 50 Hz). As a result, we obtained a high level of stability for such mirror systems and we almost met the target value for the first mode of vibration.

scholarly journals Finite elements with continuous stress fields in calculation of folded prismatic thin-walled rods and shells

2018 ◽  
Vol 196 ◽  
pp. 01018
Author(s):  
Sergey Nazarenko ◽  
Nina Blokhina
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Degrees Of Freedom ◽  
High Efficiency ◽  
Stress Fields ◽  
Displacement Fields ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Shell Finite Element ◽  
Rectangular Shell

The article deals with methods of creating a rectangular wall-beam finite element with eight degrees of freedom per node and continuous stress fields along the boundaries. This effect is achieved by specifying displacement fields in the plane of the element in forms similar to those in finite elements of Bogner, Fox, and Schmitt plate. The article provides algebraic expressions for displacement forms; methods of forming reaction and stress matrices are also considered. Test calculations carried out with the help of “Computational mechanics” FEM complex have proved high efficiency of the finite element analysis performed. A rectangular shell finite element with twelve degrees of freedom per node was developed as a combination of membrane finite element and Bogner, Fox and Schmitt plate element.

Finite Element Analysis of a Highly Parallel Robotic Surface

2011 ◽  
Author(s):  
Chris Salisbury ◽  
Woosoon Yim
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Angular Displacement ◽  
Three Dimensional ◽  
Open Loop ◽  
Element Analysis ◽  
Loop Control ◽  
Stiffness Matrices ◽  
6 Degrees Of Freedom ◽  
Local Stiffness

A novel three-dimensional robotic surface is devised and implemented using triangular modules. Each module is connected by a passive sixbar mechanism that mimics the constraints of a spherical joint at each triangle intersection. The finite element method (FEM) is applied to the static loading of this device using linear three dimensional (6 degrees of freedom) beam elements to calculate the cartesian displacement and force and the angular displacement and torque at each joint. In this way, the traditional methods of finding joint forces and torques are completely bypassed. An effiecient algorithm is developed to linearly combine local stiffness matrices into a full structural stiffness matrix for the easy application of loads. This is then decomposed back into the local matrices to easily obtain joint variables used in the design and open-loop control of the surface.

scholarly journals DAMAGE ANALYSIS AND DESIGN OF ADDITIONAL CROSS BEAM REINFORCEMENT USING FE METHOD = ANALISA KERUSAKAN DAN MERANCANG TAMBAHAN KONSTRUKSI PENGUAT UNTUK PENINGKATAN KEKUATAN BATANG LINTANG DENGAN TRIAL AND ERROR MENGGUNAKAN METODA ELEMEN HINGGA

2019 ◽  
Vol 13 (1) ◽  
pp. 1
Author(s):  
Agus Sasmito ◽  
Tresna Priyana Soemardi ◽  
Harkali Setyono ◽  
Abdul Rohman Farid
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Damage ◽  
Damage Mechanism ◽  
Trial And Error ◽  
Fe Method ◽  
Element Analysis ◽  
Analysis And Design ◽  
The Finite Element Analysis ◽  
Beam Damage

The paper focuses on structural damage of cross beam arms  for brake rod in the car of  train. Analysis of cross beam was based on the design and actual conditions of the car application. Investigation the cross beam damage was done by finite element analysis. Based on the finite element analysis results, it is known  that damage mechanism  and design fault were caused by yield stress of cross beam that exceededthe material yield strength.Futher, a design improvement  of  cross beam was done by additional structure that can reduce the stress into  safe limits.AbstrakRiset ini fokus pada kerusakan struktur batang lintang yang berfungsi untuk dudukan lengan rem pada kereta makan pada rangkaian kereta api. Analisa kerusakan batang lintang didasarkan pada kondisi desain dan kondisi aktual pemakaianya. Investigasi kerusakan batang lintang dilakukan dengan analisa finite elemen. Berdasarkan pada hasil analisa diketahui faktor penyebab dan mekanisme kerusakan pada batang lintang adalah akibat kesalahan desain yang menyebabkan tegangan melampaui tegangan yield material, selanjutnya dibuat perbaikan desain untuk kereta yang telah diproduksi dengan membuat struktur penguat sehingga tegangan yang terjadi turun pada batas aman. Kata Kunci    : Analisa Kerusakan, Kereta Api, Finite Element, Cross Beam, Beban Eksentrik.  

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