Fig 16 - uploaded by Fabrice Pierron
Content may be subject to copyright.
Source publication
The present paper deals with full-field strain measurement on glass/epoxy composite tensile specimens submitted to high strain
rate loading through a split Hopkinson pressure bar (SHPB) device and with the identification of their mechanical properties.
First, the adopted methodology is presented: the device, including an Ultra-High Speed camera, an...
Similar publications
Periodontal disease is a widely distributed disease worldwide. It affects life quality and causes many health problems. The cause of periodontal disease is bacterial infection. The key to treating periodontal disease is killing bacteria and thus using a local antibiotic agent is a good way of treating periodontal disease. In our work, we loaded ber...
In this study, we performed finite element method simulations to investigate the effect of the structure on the elastic response of Ag and Au nanowires (NWs) with a fivefold twinned crystal structure in bending tests. Two different models of a pentagonal NW were created: a 'uniform model' having an isotropic continuous structure and a 'segmented mo...
To comprehensively understand the quantitative mechanical–thermal properties and fracture mechanisms of Zr-based bulk metallic glass (BMG), by using self-made miniature tensile/compressive device and motor-piezoelectric coupling driven fatigue device, a series of static and dynamic mechanical tests at elevated temperatures of bulk Zr55Cu30Al10Ni5 B...
Malaysia, especially the Borneo Island state of Sarawak, has a large variety of tropical wood species. In this study, selected raw tropical wood species namely Artocarpus Elasticus, Artocarpus Rigidus, Xylopia spp., Koompassia Malaccensis, and Eugenia spp. were chemically treated with sodium metaperiodate to convert them into plasticized wood (PW)....
In this work, we report the synthesis and study of nanocomposites with a biobased epoxy/amine (Epilok 60-600G/Curamine 30-952) matrix reinforced with reduced graphene oxide (rGO) or functionalised with 3-glycidoxypropyltrimethoxysilane (GLYMO-rGO). These graphene related materials (GRMs) were first dispersed into a Curamine hardener using bath ultr...
Citations
... This method focuses on tests performed with high strain rates and above room temperature [6]. In this approach, the full-field accelerations are calculated and used as image-embedded load cells to find the stiffness of the material without external measurement of the applied force [7]. In this test, vibration-induced heating [8] (self-heating or hysteretic heating) is taken advantage of to heat the sample during the experiments and create a temperature variation along the sample. ...
This study presents a novel methodology for estimating the master curve of the complex modulus of viscoelastic materials using a combination of optical measurement systems and ultrasonic excitation. Traditional techniques for characterizing properties of viscoelastic materials are often time-consuming and encounter limitations that hinder their accuracy at high strain rates. To address this, a method was proposed that leverages two optical measurement systems to quickly assess material properties at multiple points on a sample. A high-power ultrasonic transducer was employed to excite the material at its first longitudinal natural frequency, creating non-uniform temperature variations and strain rates. A scanning laser Doppler vibrometer measured vibrations across the material, enabling computation of the complex modulus magnitude under varying conditions. These results were correlated with temperature readings obtained from an infrared camera. The constructed master curve using the proposed methodology closely resembled those established through quasi-static and dynamic uniaxial compression tests in the literature. Additionally, this method revealed a more substantial increase in complex modulus at high strain rates compared to traditional experiments, where this characteristic is less pronounced.
... The model parameters are evaluated based on the stress equilibirium described by the PVW with particular virtual fields. In the case of elasticity, the linear stress-strain relationship allows for the constitutive parameters to be directly identified using a matrix inversion [14]. If a non-linear constitutive relationship is considered, the model parameters are obtained by minimising a cost function built from the difference between internal and external virtual works. ...
... The VFM can be applied to any kind of behaviour. It has been used to identify elastic [14], plastic [29], viscoplastic [30], anisotropic [31,32] and viscoelastic [15,33] material models, among others. ...
... For linear elastic constitutive models, the stress σ is linearly dependant on the strains. So, Equation (9) can then be expressed in order to allow for a direct matrix inversion for the identification of elastic properties [13,14]. This is referred to as the linear VFM. ...
... The necessary full-field deformation measurements required to apply the approach in two dimensions can be obtained using DIC [1], the grid method [40,41], or particle image velocimetry [42]. Section 6 shows that the three dimensional system of equations can be reduced to two dimensions, under the assumption that the out of plane shear components are negligible, the assumption that the stress is homogeneous in the third dimension, and the assumption that the material is incompressible. ...
... The virtual field (VFM) method is applied on the heterogeneous tensile test. This method is wildly used for the identification of mechanical behavior of linear elastic materials [17][18][19][20][21][22]. In the recent past, the VFM method is applied for the identification of hyperelastic constitutive parameters [19] or viscoelastic properties of rubber under dynamic tests [20]. ...
... This method is wildly used for the identification of mechanical behavior of linear elastic materials [17][18][19][20][21][22]. In the recent past, the VFM method is applied for the identification of hyperelastic constitutive parameters [19] or viscoelastic properties of rubber under dynamic tests [20]. ...
The stretch blowing process for PET bottle induces the anisotropic mechanical properties due to the different elongation of macromolecular chains. For example, the Young's modulus can be multiplied by almost two in the longitudinal direction and more than 3 times in the hoop direction of the plastic bottle. However, the process is complex and the elastic properties present dispersions which depend on the process condition. Therefore, it is necessary that the 5 parameters from the orthotropic elastic properties can be all obtained during a single realization. The symmetry of the elasticity tensor reduces to 4 characteristics to be determined. To achieve this identification process, firstly, the displacement field is measured using image correlation and biaxial tests are carried out on a machine developed in our laboratory. Then, the virtual field method on a specific cruciform specimen with a hole is managed to identify the orthotropic elastic properties. The optimal position of the hole is also studied. Finally, the identified orthotropic constitutive parameters from this method are compared to the results obtained by classical methods.
... Using this method, the value of strain in known only at the points where the strain gauges are located and the determination of principal strains requires the use of strain gauge rosettes. In order to have full field strain measurement, several optical techniques were developed, such as the digital image correlation, mark tracking or grid methods, which are better alternatives for characterizing mechanical behavior in the case of PCBs [10][11][12]. According to documentation, digital image correlation (DIC) was successfully employed to determine the thermal deformations in many applications [13][14][15][16][17][18][19]. ...
... Then, the subset position after deformation is found. measurement, several optical techniques were developed, such as the digital image correlation, mark tracking or grid methods, which are better alternatives for characterizing mechanical behavior in the case of PCBs [10][11][12]. ...
The paper proposed an alternative optical metrology to classical methods (strain gauge measurements and numerical simulation) for strain determination on printed circuit board (PCBs) due to thermal loads. The digital image correlation (DIC) technique was employed to record the strain distribution in some particular areas of the PCB. A thermal load was applied using a heating chamber, and the measurements were performed at four different temperature steps (25 °C, 50 °C, 85 °C and 120 °C). An increase in the principal strains with temperature was observed. For validation, the principal strains on the PCB obtained with DIC were compared with the values from gauge strain measurements and numerical simulation. The conclusions highlighted that DIC represents a technique with potential for strain measurement caused by thermal deformation, with the advantages of full field measurement, less preparation of the surface and good accuracy.
... Ainsi il est possible de déterminer les contraintes associées, ainsi que la distribution d'effort. Dans le cas où la structure est considérée hétérogène, pour les matériaux multicouches, il est nécessaire d'adapter la formulation des champs virtuels [80]. L'avantage de cette méthode est qu'elle permet de réduire les dérivées spatiales à l'ordre 2, et elle ne nécessite pas de régularisation. ...
Les nouvelles contraintes écologiques nécessitent de repenser les véhicules de demain. Un des défis des constructeurs et équipementiers automobiles est l’allègement des véhicules. Une approche est de repenser les mousses d’habillage et leurs emplacements, normalement présentes pour le confort acoustique, pour dissiper l’énergie vibratoire des caisses automobiles à la place de dispositifs ajoutés sur les tôles.Dans des structure bicouches « plaque acier - matériau poreux », les phénomènes d’amortissement (externe, interne ou d’interface) et leurs modèles (visqueux, hystériques, frottement, …) associés sont multiples, avec une dépendance en espace et en fréquence importante. Dans cette thèse, les paramètres usuellement utilisés pour décrire la dissipation d’énergie dans une structure (coefficient et taux d’amortissement, facteur de perte, …) sont définis pour mettre en avant les équivalences possibles entre les différents modèles de dissipation. C’est ainsi qu’un facteur de perte équivalent est utilisé pour définir l’amortissement local d’une structure bicouches quel que soit le phénomène de dissipation. Pour identifier ce paramètre, des techniques expérimentales sont présentées, avec une focalisation vers les méthodes de Résolution Inverse (RI, RIFF, RIC, RIB). Ce type de méthode est particulièrement pratique pour caractériser localement les paramètres de structures bicouches. Une combinaison de deux de ces méthodes permet d’augmenter la bande de fréquences d’identification. Pour valider l’approche utilisée, une structure académique (poutre bi-appuyée) simulée avec différents éléments d’amortissement (amortisseurs visqueux, frotteurs) permet de mettre en avant l’influence de ces éléments dans le domaine fréquentiel et dans l’espace. De plus, ces résultats numériques apportent une base de comparaison pour comprendre quels mécanismes d’amortissement interviennent dans des systèmes réels. Un banc de mesure utilisant un vibromètre laser pour mesurer le champ de déplacement d’une plaque support en acier surmontée d’une mousse pour différents contacts à l’interface (mousse collée ou posée) est présenté. Celui-ci permet de quantifier le facteur de perte équivalent à l’aide de la méthode de résolution inverse. Dans le cas d’une mousse collée, la comparaison du facteur de perte équivalent avec son évaluation par éléments finis permet de démontrer que l’effet viscoélastique de la mousse s’avère être le phénomène physique principal responsable de l’amortissement des vibrations. En revanche dans le cas d’une mousse posée, le facteur de perte équivalent expérimental décrit un comportement de la structure très différent, ce qui induit un mécanisme plus difficile à comprendre. Des enregistrements par une caméra rapide permettent d’observer le frottement ou rebond possible à l’interface mousse-plaque, ce qui influe de manière non négligeable sur l’énergie dissipée dans des gammes de fréquences très basses, en complémentarité avec le comportement viscoélastique des mousses collées. Cela permet de conclure que les phénomènes complémentaires d’amortissement de mousses posées et collées peuvent être envisagés dès la conception du véhicule en optimisant leur emplacement par rapport aux domaines fréquentiels où ils doivent agir.
... In the last few years, these difficulties has been partially tackled. Indeed, the progress in ultra high-speed imaging paired with digital image correlation made possible measurements at precise resolutions (a few µm and µs) [Moulart et al., 2011,Malchow et al., 2019. This opened the way to the realization of heterogeneous tests and enables the identification of dynamic constitutive parameters [Kajberg andWikman, 2007, Peirs et al., 2011]. ...
... While a series of works has used such technology to observe in details dynamic processes and even extract some fracture mechanics parameters, only a couple have achieved quantitative measurements and performed a metrological analysis of such cameras, where important measurement bias can arise due to the multiplicity of the optical paths [Kirugulige et al., 2007, Pierron et al., 2011a, Moulart et al., 2011. Moreover, in these few valuable works, displacement and strain noise floors were evaluated using a route that may be questionable. ...
... Finally, u ss denotes the displacements obtained when using a sensor-to-sensor approach (e.g. [Moulart et al., 2011]). From this figure, the following relation can be deduced: ...
To this date, the experimental and analytical strategies allowing to characterize the visco-thermomechanical behaviour of materials subjected to extreme and complex loadings are limited. In this context, this thesis proposes to develop an innovative strategy combining heterogeneous tests, full-field measurements at ultra-high speed and a non-parametric stress field reconstruction method.The work of this thesis relies on the joint use of an ultra-high speed camera (Cordin-580) and a high speed infrared camera (Telops M3K), which present to date the best spatio-temporal resolutions of the market, to capture the thermomechanical fields during a heterogeneous test. To do so, dedicated methods allowing to measure with a high spatial sampling strains (uncertainty of 2 mm/m) and temperatures (uncertainty of 0.3 °C) for high acquisition speeds are developed.An experimental campaign allowing to cover large ranges of strain, strain-rate, temperature and triaxiality in a single test, while ensuring their measurability is then designed.Finally, the proposed test is analysed with an original method of stress field reconstruction which allows to characterize in a single test the visco-plastic response of a steel over a range of strain-rate from 10 per second to 500 per second with uncertainties of 10%, while providing loading paths that partially cover the shear and compression response. The combined evaluation of temperature and stress fields allow the local evaluation of energy, which will likely allow in the near future thermodynamically based models to be established using a reduced number of tests.
... According to Hooke's Law, if a plane stress condition is applied to an orthotropic material, the relationship between stress and strain in the global coordinate system can be expressed by [50]: ...
This work aims to determine the orthotropic linear elastic constitutive parameters of Pinus pinaster Ait. wood from a single uniaxial compressive experimental test, under quasi-static loading conditions, based on two different specimen configurations: (a) on-axis rectangular specimens oriented on the radial-tangential plane, (b) off-axis specimens with a grain angle of about 60(radial-tangential plane). Using digital image correlation (DIC), full-field displacement and strain maps are obtained and used to identify the four orthotropic elastic parameters using the finite element model updating (FEMU) technique. Based on the FE data, a synthetic image reconstruction approach is proposed by coupling the inverse identification method with synthetically deformed images, which are then processed by DIC and compared with the experimental results. The proposed methodology is first validated by employing a DIC-levelled FEA reference in the identification procedure. The impact of the DIC setting parameters on the identification results is systematically investigated. This influence appears to be stronger when the parameter is less sensitive to the experimental setup used. When using on-axis specimen configuration, three orthotropic parameters of Pinus pinaster (ER, ET and νRT) are correctly identified, while the shear modulus (GRT) is robustly identified when using off-axis specimen configuration.
... Damage accumulates in a widespread fashion in composites, and many individual processes occur at the micro structural level [19], [20]. Apart from that, there are debates on whether hybridization of CFRP/GFRP exhibits unique deformation for distinct layups of Unidirectional [21], Balanced Crossply [22], Quasi Isotropic [23] under tensile, flexural loading and their failure modes. The general finding was that quasi-UD composites exhibit nonlinear stress-strain behavior when they were subjected to transverse loading [17]. ...
... Significant findings have been observed on the mechanical characterization of woven, cross-ply and quasiisotropic made of one constituent of composite material [23], [65], [68]. The relatively low ratio of the compressive to the tensile strength of carbon fibre may be a disadvantage to the use of carbon fibre reinforced polymers (CFRP) composites as structural elements members subjected to compressive and flexural loading [69]. ...
Composite is the combination of two or more materials that differ in properties and composition to form unique properties. This paper reported the deformation of hybrid composite under tensile, shear and flexural loading. This review provides insight and state of the art for mechanics of composites that provides underlying theory for understanding the deformation and behaviour for the hybrid composite under various loading conditions. This paper also discusses mechanical behaviour of hybrid composites under static loading (Tensile, Shear, Flexural). It is essential to understand the principle that governs the mechanics of composites of laminate under loading which also applicable to hybrid composites C/GFRP.The high modulus fibre, such as Carbon fibre offers stiffness and load bearing capabilities, whereas the low modulus fibre, such as glass fibre makes the composite more durable and low in cost
... With the ongoing requirement to obtain material properties at strain rates on the order of a few thousand s −1 , it is important that techniques with fewer restrictions are developed. Recently, new experimental techniques based on the use of full-field measurements have emerged [26,27]. An example of this is the Image Based Inertial Impact (IBII) test described in [28,29]. ...
... The VFM was also used to characterise failure in a concrete specimen in [73,74] without relying on the interpretation of 1D signals from the rear surface of the specimen, as in [75]. Other applications of the VFM in dynamics have been performed on composites [26,27] tungsten carbide ceramic-metallics (cermets) [28], rubber [76] and metals [77]. A VFM-inspired approach was also used for foams in [78] and rubber in [79]. ...
... One limitation of using full-field measurements within the VFM is that if specimen strains are low, noise levels can significantly influence the quality of the derived material parameters [72]. However, a well designed test that generates sufficient signal to noise ratios can yield accurate dynamic material properties [26]. An emerging experimental test methodology that uses full-field measurements and the VFM in dynamic applications is described in the next section. ...
