scholarly journals Identification of Materials Properties Using Displacement Field Measurement

2011 ◽  
Vol 482 ◽  
pp. 57-65 ◽  
Author(s):  
Marina Fazzini ◽  
Olivier Dalverny ◽  
Sébastien Mistou
Keyword(s):  
Finite Element ◽  
Displacement Field ◽  
Model Updating ◽  
Virtual Work ◽  
Field Measurements ◽  
Element Model ◽  
Field Method ◽  
Element Analysis ◽  
Virtual Field ◽  
Constitutive Parameters

The aim of this work is to identify parameters driving constitutive equations of materials with displacement field measurements carried out by image stereo-correlation during an unidirectional tensile test. We evaluate two identification techniques. The first one is the virtual fields method which consists in writing the principle of virtual work with particular virtual fields. It is generally used in the case of linear elasticity and it requires a perfect knowledge of the model in terms of boundary condition since the virtual fields used must be kinematically admissible. This method allows to determine parameters by a direct and fast calculation, without iterations. The second method is the finite element model updating method. It consists in finding constitutive parameters that achieve the best match between finite element analysis quantities and their experimental counterparts. This method is more adaptable than the virtual field method but it needs to spend more calculation time.

Dynamic Characteristics and Finite Element Model Updating of Micromachined Torsion Structures

2013 ◽  
Vol 284-287 ◽  
pp. 1831-1835
Author(s):  
Wei Hsin Gau ◽  
Kun Nan Chen ◽  
Yunn Lin Hwang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Speckle Pattern ◽  
Element Model ◽  
Mode Shapes ◽  
Electronic Speckle Pattern Interferometry ◽  
Finite Element Model Updating ◽  
Element Analysis

In this paper, two experimental techniques, Electronic Speckle Pattern Interferometry and Stroboscopic Interferometry, and two different finite element analysis packages are used to measure or to analyze the frequencies and mode shapes of a micromachined, cross-shaped torsion structure. Four sets of modal data are compared and shown having a significant discrepancy in their frequency values, although their mode shapes are quite consistent. Inconsistency in the frequency results due to erroneous inputs of geometrical and material parameters to the finite element analysis can be salvaged by applying the finite element model updating procedure. Two updating cases show that the optimization sequences converge quickly and significant improvements in frequency prediction are achieved. With the inclusion of the thickness parameter, the second case yields a maximum of under 0.4% in frequency difference, and all parameters attain more reliable updated values.

An Energy Transmitting Boundary for Semi-Infinite Structures

2007 ◽  
Vol 23 (2) ◽  
pp. 159-172
Author(s):  
S.-S. Chen ◽  
W.-C. Hsu
Keyword(s):  
Finite Element ◽  
Analytical Model ◽  
Virtual Work ◽  
Element Model ◽  
Absorption Mechanism ◽  
Element Analysis ◽  
Reflected Waves ◽  
Infinite Region ◽  
Model Size ◽  
Transmitting Boundary

AbstractA soil-structure system associated with a semi-infinite structure such as tunnel or pavement is usually investigated by finite element analysis. If the boundary of the finite element model selected is not far enough from the excitation source or does not have an appropriate energy-absorption mechanism, it may introduce a significant error induced by reflected waves. This study develops a structural transmitting boundary to absorb the transmitting energy at the boundary of the analytical model. The structure is divided into finite and semi-infinite regions. The stiffness of the semi-infinite region is established by the principle of virtual work and applied at the transmitting boundary. The comparisons of the structural displacements induced by vertical harmonic excitations show that the analytical model size can be significantly reduced, if the proposed transmitting boundary is used to simulate the semi-infinite structural region.

A Correlation Improvement Technique for Model Updating of Structures

2016 ◽  
Vol 16 (08) ◽  
pp. 1550049 ◽  
Author(s):  
Fatih Altunel ◽  
Mehmet Çelik ◽  
Mehmet Çalişkan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Model Updating ◽  
Element Model ◽  
Modal Assurance Criterion ◽  
Element Analysis ◽  
New Correlation ◽  
The Finite Element Analysis ◽  
Node Removal ◽  
The Finite Element Model

This study proposes a new correlation improvement technique for the optimum node removal location to get improved modal assurance criterion (MAC) matrix. The technique is applied to updating of the finite element model (FEM) of a structure. The developed routine is tried on a utility helicopter. It is proven that it is capable of showing better performance than the coordinate MAC (coMAC), commonly used in such analyses. Commercial software is utilized for the finite element analysis of the helicopter fuselage and tail. Experimental modal analyses are also performed for updating the model for tail of the helicopter to demonstrate the effectiveness of the new technique.

scholarly journals Extracting elastic constitutive parameters using the VFM within peridynamics

2019 ◽  
Author(s):  
Rolland Delorme ◽  
Patrick Diehl ◽  
Ilyass Tabiai ◽  
Louis Laberge Lebel ◽  
Martin Levesque
Keyword(s):  
Finite Element ◽  
Displacement Field ◽  
Material Properties ◽  
Noise Analysis ◽  
Image Correlation ◽  
Bending Test ◽  
Virtual Fields Method ◽  
Element Analysis ◽  
Constitutive Parameters

This paper implements the Virtual Fields Method within the ordinary state based peridynamic framework to identify material properties. The key equations derived in this approach are based on the principle of virtual works written under the ordinary state based peridynamic formalism for two-dimensional isotropic linear elasticity. In-house codes including a minimization process have also been developed to implement the method. A three-point bending test and two independent virtual fields arbitrarily chosen are used as a case study throughout the paper. The numerical validation of the virtual fields method has been performed on the case study by simulating the displacement field by finite element analysis. This field has been used to extract the elastic material properties and compared them to those used as input in the finite element model, showing the robustness of the approach. Noise analysis and the effect of the missing displacement fields on the specimen’s edges to simulate digital image correlation limitations have also been studied in the numerical part. This work focuses on pre-damage properties to demonstrate the feasibility of the method and provides a new tool for using full-field measurements within peridynamics with a reduced calculation time as there is no need to compute the displacement field. Future works will deal with damage properties which is the main strength of peridynamics.

Analysis of progressive deformation of the Edmonton Convention Centre excavation

1987 ◽  
Vol 24 (3) ◽  
pp. 430-440 ◽  
Author(s):  
D. H. Chan ◽  
N. R. Morgenstern
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Strain Softening ◽  
Progressive Failure ◽  
Field Measurements ◽  
Shear Zones ◽  
Element Model ◽  
Progressive Deformation ◽  
Element Analysis ◽  
The Stability

A finite element analysis was performed of the deformations observed during the excavation of the Edmonton Convention Centre. Local geology in the Edmonton area consists of layers of shale with weak bentonite seams overlain by glacial deposits. The presence of the bentonite seams, which possess strain-softening characteristics, controls the stability of the excavation, which is located in a valley wall. To simulate the influence of the bentonite seams a strain-softening finite element model is used to estimate the amount of deformation in the foundation of the excavation. Field measurements indicated that localized progressive straining had occurred during the excavation process, and substantial heave of the foundation floor was observed. The finite element results show progressive deformation of the excavation and propagation of shear zones. Good agreement between the finite element results and the field observations is obtained. Key words: progressive failure, strain softening, finite element analysis, shear band, excavation stability.

Stress Analysis and Identification with Full-Field Measurements

2006 ◽  
Vol 3-4 ◽  
pp. 9-16 ◽  
Author(s):  
M. Grédiac
Keyword(s):  
Model Updating ◽  
Measurement Techniques ◽  
Field Measurements ◽  
Element Model ◽  
Finite Element Model Updating ◽  
Strain Fields ◽  
Full Field ◽  
Full Field Measurement ◽  
Constitutive Parameters ◽  
The Finite Element Model

The wealth of information provided by full-field measurement techniques is very useful in experimental mechanics. Among different possible applications, full-field measurements can be used to identify parameters governing constitutive equations from heterogeneous strain fields. This keynote lecture first describes the different possible uses of such measurements. It then focuses on the virtual fields method which has been proposed to extract constitutive parameters from full-field measurements. Finally, the method is compared with the finite element model updating technique which is usually used for solving such a problem.

scholarly journals Model Updating and Structural Optimization of Circular Saw Blades with Internal Slots

2014 ◽  
Vol 6 ◽  
pp. 546496
Author(s):  
Wei-Hsin Gau ◽  
Kun-Nan Chen ◽  
Yunn-Lin Hwang
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Structural Integrity ◽  
Model Updating ◽  
Element Model ◽  
Frequency Separation ◽  
Element Analysis ◽  
Sizing Optimization ◽  
Rotating Speed ◽  
Circular Saw

Circular diamond saws rotating in high speed are widely used to cut hard materials, and narrow slots on saw blades are sometimes used to reduce the blades' vibration and noise. Sizing optimization of the internal, annular slots on saw blades is investigated in this paper. First, an accurate finite element model representing an actual saw blade is obtained by model updating. Then, sizing optimization on two types of annular slots is performed to maximize the frequency separation between the finite element analysis results and the saw blade's operational speed and to reduce the possibility of structural resonance. Optimization results demonstrate great improvements in frequency separation from the rotating speed of 500 Hz for the optimized models, and stress analyses on the optimized blade models confirm the structural integrity of the designs.

Finite Element Model Updating of Existing T-Girder Bridge by Field Quasi-Static Generalized Influence Line

2012 ◽  
Vol 226-228 ◽  
pp. 1609-1613 ◽  
Author(s):  
Jing Bo Liao ◽  
Guang Wu Tang ◽  
Fei Pan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Structural Damage ◽  
Model Updating ◽  
Element Model ◽  
Finite Element Model Updating ◽  
Element Analysis ◽  
Influence Line ◽  
Girder Bridge ◽  
The Finite Element Model

Finite element model updating is the important foundation of structural damage detection, condition assessment for engineering structure. A new method, for finite element model updating based on the quasi-static generalized influence line (QSGIL) residual objection, is presented to update the finite element model of beam-structure in order to improve the quality and precision of finite element analysis. Both of the theory and model experimental study show that the proposal method can efficiently update the finite element model in the previous study [1]. In this paper, the updating techniques are further developed to update the finite element model of the existing T-Girder bridge, the QSGIL of the updating model agrees very well with the field QSGIL of the existing bridge, which illustrates that the proposal methodology is promising in the practical bridge structure and other structures.

Layer-wise finite-element analysis of a functionally graded hollow thick cylinder with a piezoelectric ring

2011 ◽  
Vol 225 (5) ◽  
pp. 1045-1060 ◽  
Author(s):  
M H Yas ◽  
M Shakeri ◽  
M Khanjani
Keyword(s):  
Finite Element ◽  
Potential Energy ◽  
Virtual Work ◽  
Electrical Potential ◽  
Element Model ◽  
Functionally Graded ◽  
Dynamic Responses ◽  
Element Formulation ◽  
Element Analysis ◽  
Thick Cylinder

In this work, a layer-wise finite-element formulation is developed for the analysis of a functionally graded material (FGM) hollow thick cylinder with one piezoactuator ring. The cylinder and ring is divided into many sublayers in the thickness direction and the full layer-wise shell theory is used to model a discretely stiffened FGM cylinder. In this model, the displacements are approximated linearly through each mathematical layer. This accounts for any discontinuities in the derivatives of the displacement at the interface of the ring and the cylindrical thick shell. This formulation is derived from the virtual work statement which includes the total structural potential energy and the electrical potential energy of the piezoelectric ring. Assembling stiffness and mass matrices, at each interface between two elements, stress and displacement continuity are forced, and then the finite-element model is solved. Static and dynamic responses of a functionally graded thick cylinder to electrical and mechanical loads with different exponent ‘ n’ of FGM are determined to show the significant influence of the material in homogeneity. The results obtained at a distance far from the ring are compared with the mechanical behaviour of an FGM cylindrical shell without a ring. Because of the Saint Venant effects, the piezoelectrically induced deformation of the shell is confined to a region close to the piezoelectric ring; thus agreements between these two results are observed.

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