scholarly journals Identification from measurements of mechanical fields by finite element model updating strategies

2009 ◽  
pp. 353-376
Author(s):  
Patrick Ienny ◽  
Anne-Sophie Caro-Bretelle ◽  
Emmanuel Pagnacco
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Inverse Method ◽  
Model Updating ◽  
Field Measurements ◽  
Element Model ◽  
Element Modelling ◽  
Identification Process ◽  
Problem Resolution

Inverse problem resolution methods are widely used in the determination of material behaviour. The optimisation of the parameters, as inputs into a well-defined system, is obtained from observed outputs such as kinematic field measurements. The aim of this paper is to summarize the research concerning one inverse method, Finite Element Modelling Updating, based on the use of these field measurements. This method is based on a combination of three components, described in the following three sections. First we present the optical field measurements applied to multi-axially loaded objects, together with their performances. Then we outline the use of Finite Element Modelling for achieving a correlation between numerical fields and their experimental counterparts. Finally we describe the identification process, together with cost functions, minimisation procedure and model validation analysis.

scholarly journals Stiffness Estimation and Equivalence of Boundary Conditions in FEM Models

2021 ◽  
Vol 11 (4) ◽  
pp. 1482
Author(s):  
Róbert Huňady ◽  
Pavol Lengvarský ◽  
Peter Pavelka ◽  
Adam Kaľavský ◽  
Jakub Mlotek
Keyword(s):  
Boundary Condition ◽  
Finite Element ◽  
Boundary Conditions ◽  
Model Updating ◽  
Element Model ◽  
Computational Time ◽  
Stiffness Coefficients ◽  
First Case ◽  
Numerical Approaches

The paper deals with methods of equivalence of boundary conditions in finite element models that are based on finite element model updating technique. The proposed methods are based on the determination of the stiffness parameters in the section plate or region, where the boundary condition or the removed part of the model is replaced by the bushing connector. Two methods for determining its elastic properties are described. In the first case, the stiffness coefficients are determined by a series of static finite element analyses that are used to obtain the response of the removed part to the six basic types of loads. The second method is a combination of experimental and numerical approaches. The natural frequencies obtained by the measurement are used in finite element (FE) optimization, in which the response of the model is tuned by changing the stiffness coefficients of the bushing. Both methods provide a good estimate of the stiffness at the region where the model is replaced by an equivalent boundary condition. This increases the accuracy of the numerical model and also saves computational time and capacity due to element reduction.

Impact Analysis of an Oxygen Mask Locking Panel of Aircraft Using Finite Element Modelling

2014 ◽  
Vol 657 ◽  
pp. 735-739 ◽  
Author(s):  
Emilian Ionut Croitoru ◽  
Gheorghe Oancea
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Impact Analysis ◽  
Element Model ◽  
Composite Panel ◽  
Cad Model ◽  
Stress Variation ◽  
Element Modelling ◽  
Oxygen Mask ◽  
The Impact

This paper presents a method of finite element modelling used for the impact analysis of a composite panel. In this research, the composite panel consists of an oxygen mask locking panel of an aircraft. This panel is loaded with one concentrated abuse loading and three uniform distributed abuse loading cases and the stress variation within the composite panel for each load case is determined. In order to assess the impact analysis on the oxygen mask panel of the aircraft, a finite element model is created using Patran as the main application for pre/post-processing and Nastran as the main processor. The paper also presents a comparison between results obtained using the same finite element modelling of the composite panel CAD model of the panel with four load cases with different material types. The results are used to determine the most capable material stresswise.

scholarly journals ROTATIONAL STIFFNESS DETERMINATION OF THE SEMI-RIGID TIMBER-STEEL CONNECTION

2017 ◽  
Vol 23 (8) ◽  
pp. 1021-1028
Author(s):  
Tomas GEČYS ◽  
Alfonsas DANIŪNAS
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Bending Moment ◽  
Steel Structures ◽  
Rotational Stiffness ◽  
Element Modelling ◽  
Component Method ◽  
Steel Connection ◽  
Timber Connections

In this research, the component method implementation for determination of the rotational stiffness of timber-steel connection is shown. Component method is one of the most commonly used methods for determination of the bending moment-rotation relation which later may be used in the practical analysis of the connection. The component method is not widely used for the analysis of the semi-rigid timber connections. There are only several investigations previously done on the component method implementation for the timber connections and most of them are based on only one basic component, i.e. timber compression or glued-in steel rod in tension. This article presents a new investigation of rotational stiffness determination algorithm of the semi-rigid timber-steel connection, which is based on the component method. The component method’s mechanical model of the connection combines all components which have influence on the rotational stiffness of the connection. The analysed timber-steel connection is subjected to pure bending. Stiffness coefficients of the steel part components are determined according to the Eurocode 3: design of steel structures Part 1-8: Design of joints. The timber part components are derived from the full-scale laboratory experiments and finite element modelling results, presented in the previous publications of the authors. The presented rotational stiffness determination results are well in line with the experimental and finite element modelling results, published in the previous publications.

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.

A Novel Tool Path Strategy for Modelling Complicated Perpendicular Curved Movements

2019 ◽  
Vol 796 ◽  
pp. 164-174 ◽  
Author(s):  
Bahman Meyghani ◽  
Mokhtar Awang
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Tool Path ◽  
Cnc Machining ◽  
Process Time ◽  
Efficient Tool ◽  
Element Modelling ◽  
Friction Stir ◽  
Tool Paths

Curved surfaces have been widely used in engineering applications such as friction stir welding (FSW), 5 axis CNC machining, and other processes. Therefore, the development of the finite element modelling of the complicated geometries has created a need to determine efficient tool paths. Previous finite element models modelled the single point movement of the tool. However, in industrial applications such as aerospace, mould and die, etc. the movement of the tool is complex. Proper determination of the tool path can lead to substantial savings of the process time, improvement of the workpiece surface quality and the improvement of the tool life, thereby leading to overall cost reduction and higher productivity. This paper presents a new approach for the determination of efficient tool paths in finite element modelling by using ABAQUS® software. VDISP user defined subroutine is used in order to define the complex curved movement of the tool. The results indicate that the method is appropriate for modelling of the tool path, and the tool always has a perpendicular position to the surface. Therefore, the method can be suitable for increasing the application of the finite element modelling in various industries.

Effect of Laminates Orientation on Impact Properties of Fiberglass and Kevlar Composite Panels

2015 ◽  
Vol 808 ◽  
pp. 119-124
Author(s):  
Emilian Ionut Croitoru ◽  
Gheorghe Oancea
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Composite Panel ◽  
Left Wing ◽  
Stress Variation ◽  
Impact Properties ◽  
Element Modelling ◽  
Loading Case ◽  
Multiple Configurations

This paper presents the study of the effect of laminates angle on impact properties of a composite panel made of glass and Kevlar fibers using finite element modelling. In this research, the composite panel consists of a skin panel, specifically the front left wing, from an automotive vehicle having multiple configurations. A distributed pressure on the composite package represents the loading on the selected panel modelled as one uniform distributed abuse loading case and the stress variation within the composite panel for each configuration is determined. The results of these analyses are used for the determination of mathematical models for tensions, longitudinal and shear tensions, as functions of laminate angle for each configuration.

Improved understanding of biscuit checking using speckle interferometry and finite-element modelling techniques

2005 ◽  
Vol 461 (2059) ◽  
pp. 2135-2154 ◽  
Author(s):  
Q Saleem ◽  
R.D Wildman ◽  
J.M Huntley ◽  
M.B Whitworth
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Numerical Study ◽  
Field Measurements ◽  
Element Model ◽  
Storage Conditions ◽  
Speckle Interferometry ◽  
Strain Measurements ◽  
Effective Strategies ◽  
Modelling Techniques

For almost a century, manufacturers have tried to understand and predict the appearance of small hairline cracks in biscuits and crackers, an effect known as ‘checking’. Results are presented here from a combined experimental and numerical study of the phenomenon. Experimentally determined material properties of semi-sweet biscuits were used as inputs to an axisymmetric finite-element model, which predicts that, at low relative humidities (RHs), the rim of the biscuit expands and the centre contracts. The expansion is caused by uptake of moisture at the rim, which is initially dry after baking, and the contraction is attributable to loss of moisture from the more moist centre. The finite-element predictions were validated by strain measurements of freshly baked biscuits using speckle interferometry. These measurements are the most sensitive and the first whole-field measurements yet made of strains in biscuits. Experiments using a range of storage conditions enable us to confirm that it is the presence of moisture gradients, in combination with a low environmental RH, which increases the chance of checking. These results will aid biscuit manufacturers in the development of more effective strategies to avoid the damaging phenomenon of checking, potentially enabling consumers to benefit from fewer broken biscuits.

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