scholarly journals On the Identification and Validation of an Anisotropic Damage Model Using Full-field Measurements

2011 ◽  
Vol 20 (8) ◽  
pp. 1130-1150 ◽  
Author(s):  
Mouldi Ben Azzouna ◽  
Jean-Noël Périé ◽  
Jean-Mathieu Guimard ◽  
François Hild ◽  
Stéphane Roux
Keyword(s):  
Finite Element ◽  
Mechanical Test ◽  
Damage Model ◽  
Element Model ◽  
Mechanical Tests ◽  
Image Correlation ◽  
Loading Path ◽  
Anisotropic Damage ◽  
Full Field ◽  
Damage Law

Two different mechanical tests are performed on a laminated composite coupon to induce an anisotropic damage affecting essentially shear modulus softening. The first test is a uniaxial tension loading on a straight coupon, which is used to evaluate the damage law using a conventional approach, while the second contains a notch that enhances dramatically the strain (and hence damage) heterogeneity. A global digital image correlation approach is used to quantify the kinematic fields all along the loading path of the second experiment. Displacement fields are hence evaluated based on a finite element type discretization. A further exploitation based on the reconditioned equilibrium gap method (and without any further information) gives access to a quantitative measurement of the damage law. The latter approach makes use of a finite element model based on the very same mesh and element shape function. This full-field-based identification method compares very well with traditional techniques, up to the stage where macroscopic localization prevents their subsequent exploitations. Moreover, it is shown that neither the type of mechanical test, nor the discretization of the displacement field, affects the identification of the damage law.

Finite element model updating from full-field vibration measurement using digital image correlation

2011 ◽  
Vol 330 (8) ◽  
pp. 1599-1620 ◽  
Author(s):  
Weizhuo Wang ◽  
John E. Mottershead ◽  
Alexander Ihle ◽  
Thorsten Siebert ◽  
Hans Reinhard Schubach
Keyword(s):  
Finite Element ◽  
Digital Image Correlation ◽  
Finite Element Model ◽  
Digital Image ◽  
Model Updating ◽  
Element Model ◽  
Image Correlation ◽  
Vibration Measurement ◽  
Finite Element Model Updating ◽  
Full Field

scholarly journals Identification of a macroscopic anisotropic damage model using digital image correlation and the equilibrium gap method

2010 ◽  
pp. 229-240
Author(s):  
Laurent Crouzeix ◽  
Jean-Noël Périé ◽  
Francis Collombet ◽  
Bernard Douchin
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Damage Model ◽  
Field Measurements ◽  
Image Correlation ◽  
Anisotropic Damage ◽  
Biaxial Test ◽  
Displacement Fields ◽  
Full Field ◽  
Constitutive Parameters

The aim of the work is to demonstrate how an anisotropic damage model may be identified from full field measurements retrieved during a heterogeneous test. The example of a biaxial test performed on a 3D C / C composite is used. In a first step, the displacement fields measured by classical Digital Image Correlation are used as input data of a finite difference version of the Equilibrium Gap Method. A benefit from unloadings (assumed to be elastic) is shown to retrieve a damage law. In a second step, inelastic strains can be assessed from the total measured strain and the elastic estimated strains. The constitutive parameters relative to the inelastic part of the model are then identified.

Experimental Validation of a Finite Element Model of the Proximal Femur Using Digital Image Correlation and a Composite Bone Model

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
A. S. Dickinson ◽  
A. C. Taylor ◽  
H. Ozturk ◽  
M. Browne
Keyword(s):  
Finite Element ◽  
Digital Image Correlation ◽  
Finite Element Model ◽  
Digital Image ◽  
Proximal Femur ◽  
Element Model ◽  
Image Correlation ◽  
Generation Process ◽  
Full Field ◽  
Biomechanical Models

Computational biomechanical models are useful tools for supporting orthopedic implant design and surgical decision making, but because they are a simplification of the clinical scenario they must be carefully validated to ensure that they are still representative. The goal of this study was to assess the validity of the generation process of a structural finite element model of the proximal femur employing the digital image correlation (DIC) strain measurement technique. A finite element analysis model of the proximal femur subjected to gait loading was generated from a CT scan of an analog composite femur, and its predicted mechanical behavior was compared with an experimental model. Whereas previous studies have employed strain gauging to obtain discreet point data for validation, in this study DIC was used for full field quantified comparison of the predicted and experimentally measured strains. The strain predicted by the computational model was in good agreement with experimental measurements, with R2 correlation values from 0.83 to 0.92 between the simulation and the tests. The sensitivity and repeatability of the strain measurements were comparable to or better than values reported in the literature for other DIC tests on tissue specimens. The experimental-model correlation was in the same range as values obtained from strain gauging, but the DIC technique produced more detailed, full field data and is potentially easier to use. As such, the findings supported the validity of the model generation process, giving greater confidence in the model’s predictions, and digital image correlation was demonstrated as a useful tool for the validation of biomechanical models.

scholarly journals Experimental and numerical analysis of fillet-welded joints under low-cycle fatigue loading by means of full-field techniques

2015 ◽  
Vol 229 (7) ◽  
pp. 1327-1338 ◽  
Author(s):  
Pasqualino Corigliano ◽  
Vincenzo Crupi ◽  
Wolfgang Fricke ◽  
Nils Friedrich ◽  
Eugenio Guglielmino
Keyword(s):  
Finite Element ◽  
Low Cycle Fatigue ◽  
Base Material ◽  
Fatigue Loading ◽  
Element Model ◽  
Image Correlation ◽  
Cycle Fatigue ◽  
Full Field ◽  
Field Techniques ◽  
The Finite Element Model

The welded structures used in the naval field are generally subjected to fluctuating stress over time. In some structural welded details, due to changing loading conditions, significant elastic-plastic deformation can arise, which may lead to the failure of the structure after a relatively low number of cycles. The aim of this scientific work was to investigate the behavior of welded T-joints under low-cycle fatigue using full-field techniques: digital image correlation and infrared thermography. Low-cycle fatigue tests were carried out on welded “small-scale” specimens with the aim of obtaining loading and boundary conditions similar to those that occur in “large-scale” components in their real operating conditions. A nonlinear finite element analysis was also performed. The material curves, relative to different zones (base material, heat-affected zone, weld), were obtained by hardness measurements, which were done by means of a fully automated hardness scanner with high resolution. This innovative technique, based on the ultrasonic contact impedance method, allowed to identify the different zones (base material, heat-affected zone, weld metal) and to assess their cyclic curves, which were considered in the finite element model. Finally, the finite element model was validated experimentally comparing the results with the measurements obtained using the digital image correlation technique. The applied procedure allows providing useful information to the development of models for the prediction of fracture and fatigue behavior of the welded joints under the low-cycle fatigue loading.

scholarly journals Experimental Characterization of the FRCM-Concrete Interface Bond Behavior Assisted by Digital Image Correlation

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1154
Author(s):  
Dario De Domenico ◽  
Antonino Quattrocchi ◽  
Damiano Alizzio ◽  
Roberto Montanini ◽  
Santi Urso ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Mechanical Tests ◽  
Image Correlation ◽  
Front Face ◽  
Full Field ◽  
Bond Behavior ◽  
Externally Bonded ◽  
Strengthening Technique ◽  
Concrete Interface

Digital Image Correlation (DIC) provides measurements without disturbing the specimen, which is a major advantage over contact methods. Additionally, DIC techniques provide full-field maps of response quantities like strains and displacements, unlike traditional methods that are limited to a local investigation. In this work, an experimental application of DIC is presented to investigate a problem of relevant interest in the civil engineering field, namely the interface behavior between externally bonded fabric reinforced cementitious mortar (FRCM) sheets and concrete substrate. This represents a widespread strengthening technique of existing reinforced concrete structures, but its effectiveness is strongly related to the bond behavior between composite fabric and underlying concrete. To investigate this phenomenon, a set of notched concrete beams are realized, reinforced with FRCM sheets on the bottom face, subsequently cured in different environmental conditions (humidity and temperature) and finally tested up to failure under three-point bending. Mechanical tests are carried out vis-à-vis DIC measurements using two distinct cameras simultaneously, one focused on the concrete front face and another focused on the FRCM-concrete interface. This experimental setup makes it possible to interpret the mechanical behavior and failure mode of the specimens not only from a traditional macroscopic viewpoint but also under a local perspective concerning the evolution of the strain distribution at the FRCM-concrete interface obtained by DIC in the pre- and postcracking phase.

Experimental Characterization and Finite Element Modeling of Film Capacitors for Automotive Applications

2016 ◽  
Author(s):  
D. Croccolo ◽  
T. M. Brugo ◽  
M. De Agostinis ◽  
S. Fini ◽  
G. Olmi
Keyword(s):  
Finite Element ◽  
Mechanical Response ◽  
High Reliability ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Life Time ◽  
Element Model ◽  
Image Correlation ◽  
Thermal Loads ◽  
Mechanical Shock

As electronics keeps on its trend towards miniaturization, increased functionality and connectivity, the need for improved reliability capacitors is growing rapidly in several industrial compartments, such as automotive, medical, aerospace and military. Particularly, recent developments of the automotive compartment, mostly due to changes in standards and regulations, are challenging the capabilities of capacitors in general, and especially film capacitors. Among the required features for a modern capacitor are the following: (i) high reliability under mechanical shock, (ii) wide working temperature range, (iii) high insulation resistance, (iv) small dimensions, (v) long expected life time and (vi) high peak withstanding voltage. This work aims at analyzing the key features that characterize the mechanical response of the capacitor towards temperature changes. Firstly, all the key components of the capacitor have been characterized, in terms of strength and stiffness, as a function of temperature. These objectives have been accomplished by means of several strain analysis methods, such as strain gauges, digital image correlation (DIC) or dynamic mechanical analysis (DMA). All the materials used to manufacture the capacitor, have been characterized, at least, with respect to their Young’s modulus and Poisson’s ratio. Then, a three-dimensional finite element model of the whole capacitor has been set up using the ANSYS code. Based on all the previously collected rehological data, the numerical model allowed to simulate the response in terms of stress and strain of each of the capacitor components when a steady state thermal load is applied. Due to noticeable differences between the thermal expansion coefficients of the capacitor components, stresses and strains build up, especially at the interface between different components, when thermal loads are applied to the assembly. Therefore, the final aim of these numerical analyses is to allow the design engineer to define structural optimization strategies, aimed at reducing the mechanical stresses on the capacitor components when thermal loads are applied.

Optimization of Osteosynthesis Positioning in Mandibular Body Fracture Management using Numerical Finite Element Method Simulation and Polymeric Model Testing

2021 ◽  
Author(s):  
Omid Daqiq ◽  
Fred W. Wubs ◽  
Ruud R. M. Bos ◽  
Baucke van Minnen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Mechanical Test ◽  
Body Height ◽  
Finite Element Method Simulation ◽  
Mechanical Tests ◽  
Body Fracture ◽  
Fracture Management ◽  
Mandibular Body ◽  
Element Method

Abstract The study aims to optimise surgical management for mandibular body fractures by application of finite element method (FEM) with verification from polymeric model tests. The study investigates two issues regarding the application of osteosynthesis plates for mandibular body fractures: the effect of miniplate positioning and mandibular body height decrease. Computed tomography (CT) images of cadaveric mandibles with heights of resp. 21, 15, and 10 mm were used to create a FEM-model with a unilateral straight-line fracture, fixated with a standard commercially available 6-hole 2 mm titanium miniplate. Outcomes were compared with a series of mechanical tests with polymeric models fixed in a customized device and loaded with a mechanical test bench. Firstly, the study illustrates that the optimal plate position appears to be the upper border. Secondly, lower mandibular height increases instability and requires a stronger fixation. Thirdly, optimal fracture reduction is essential for gaining stability. In conclusion, FEM and polymeric testing outcomes of unilateral non-comminuted fractures were highly comparable to the current opinions in mandibular fracture treatment. In future, the FEM may be used to predict the treatment of more complex fractures. However, more analysis needs to be conducted to say whether FEM alone is sufficient for fracture analysis.

Comparison of femur strain under different loading scenarios: Experimental testing

2020 ◽  
Vol 235 (1) ◽  
pp. 17-27
Author(s):  
Ievgen Levadnyi ◽  
Jan Awrejcewicz ◽  
Yan Zhang ◽  
Yaodong Gu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Strain Distribution ◽  
Element Model ◽  
Surface Strain ◽  
Image Correlation ◽  
Loading Conditions ◽  
Bone Implant ◽  
Bone Stiffness

Bone fracture, formation and adaptation are related to mechanical strains in bone. Assessing bone stiffness and strain distribution under different loading conditions may help predict diseases and improve surgical results by determining the best conditions for long-term functioning of bone-implant systems. In this study, an experimentally wide range of loading conditions (56) was used to cover the directional range spanned by the hip joint force. Loads for different stance configurations were applied to composite femurs and assessed in a material testing machine. The experimental analysis provides a better understanding of the influence of the bone inclination angle in the frontal and sagittal planes on strain distribution and stiffness. The results show that the surface strain magnitude and stiffness vary significantly under different loading conditions. For the axial compression, maximal bending is observed at the mid-shaft, and bone stiffness is also maximal. The increased inclination leads to decreased stiffness and increased magnitude of maximum strain at the distal end of the femur. For comparative analysis of results, a three-dimensional, finite element model of the femur was used. To validate the finite element model, strain gauges and digital image correlation system were employed. During validation of the model, regression analysis indicated robust agreement between the measured and predicted strains, with high correlation coefficient and low root-mean-square error of the estimate. The results of stiffnesses obtained from multi-loading conditions experiments were qualitatively compared with results obtained from a finite element analysis of the validated model of femur with the same multi-loading conditions. When the obtained numerical results are qualitatively compared with experimental ones, similarities can be noted. The developed finite element model of femur may be used as a promising tool to estimate proximal femur strength and identify the best conditions for long-term functioning of the bone-implant system in future study.

Effects of material property variation in composite panels

2017 ◽  
Vol 89 (2) ◽  
pp. 274-279
Author(s):  
Thomas Wright ◽  
Imran Hyder ◽  
Mitchell Daniels ◽  
David Kim ◽  
John P. Parmigiani
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Material Property ◽  
Material Properties ◽  
Damage Model ◽  
Element Model ◽  
Maximum Load ◽  
Content Type ◽  
Property Variation ◽  
Load Carrying

Purpose The purpose of this paper is to determine which of the ten material properties of the Hashin progressive damage model significantly affect the maximum load-carrying ability of center-notched carbon fiber panels under in-plane tension and out-of-plane bending. Design/methodology/approach The approach used is to calculate the maximum load using a finite element model for a range of material property values as specified by a fraction factorial design. The finite element model used has been experimentally validated in prior work. Findings Results showed that for the laminates considered, at most three and as few as one of the ten Hashin material properties significantly affected the magnitude of the maximum load. Practical implications While the results of this paper only specifically apply to the laminates included in the study, the results suggest that, in general, only a small number of the Hashin material properties affect laminate load-carrying ability. Originality/value Knowing which properties are significant is of value in selecting materials to optimize performance and also in determining which properties need to be known to a high accuracy.

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