Academic literature on the topic 'In-Situ micromechanical tests'
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Journal articles on the topic "In-Situ micromechanical tests":
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Choudhry, RS, Kamran A. Khan, Sohaib Z. Khan, Muhammad A. Khan, and Abid Hassan. "Micromechanical modeling of 8-harness satin weave glass fiber-reinforced composites." Journal of Composite Materials 51, no. 5 (July 28, 2016): 705–20. http://dx.doi.org/10.1177/0021998316649782.
Abstract:
This study introduces a unit cell-based finite element micromechanical model that accounts for correct post cure fabric geometry, in situ material properties and void content within the composite to accurately predict the effective elastic orthotropic properties of 8-harness satin weave glass fiber-reinforced phenolic composites. The micromechanical model utilizes a correct post cure internal architecture of weave, which was obtained through X-ray microtomography tests. Moreover, it utilizes an analytical expression to update the input material properties to account for in situ effects of resin distribution within yarn (the yarn volume fraction) and void content on yarn and matrix properties. This is generally not considered in modeling approaches available in literature and in particular, it has not been demonstrated before for finite element micromechanics models of 8-harness satin weave composites. The unit cell method is used to obtain the effective responses by applying periodic boundary conditions. The outcome of the analysis based on the proposed model is validated through experiments. After validation, the micromechanical model was further utilized to predict the unknown effective properties of the same composite.
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Bergo, Sondre, David Morin, Tore Børvik, and Odd Sture Hopperstad. "Micromechanical modelling of ductile fracture in pipeline steel using a bifurcation-enriched porous plasticity model." International Journal of Fracture 227, no. 1 (December 29, 2020): 57–78. http://dx.doi.org/10.1007/s10704-020-00495-7.
Abstract:
AbstractIn this paper, we investigate the possibility of predicting ductile fracture of pipeline steel by using the Gurson–Tvergaard–Needleman (GTN) model where the onset of void coalescence is determined based on in situ bifurcation analyses. To this end, three variants of the GTN model, one of which includes in situ bifurcation, are calibrated for a pipeline steel grade X65 using uniaxial and notch tension tests. Then plane-strain tension tests and Kahn tear tests of the same material are used for assessment of the credibility of the three models. Explicit finite element simulations are carried out for all tests using the three variants of the GTN model, and the results are compared to the experimental data. The capability of the simulation models to capture onset of fracture and crack propagation in the pipeline steel is evaluated. It is found that the use of in situ bifurcation as a criterion for onset of void coalescence in each element makes the GTN model easier to calibrate with less free parameters, all the while obtaining similar or even better predictions as other widely used formulations of the GTN model over a wide range of different stress states.
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Šittner, P., V. Novák, P. Lukáš, and M. Landa. "Stress-Strain-Temperature Behavior Due to B2-R-B19′ Transformation in NiTi Polycrystals." Journal of Engineering Materials and Technology 128, no. 3 (February 26, 2006): 268–78. http://dx.doi.org/10.1115/1.2204945.
Abstract:
Thermomechanical behavior of superelastic NiTi wires undergoing sequential B2-R-B19′ martensitic transformation was investigated by two recently developed in-situ experimental methods (in-situ neutron diffraction and combined ultrasonic and electric resistance measurements) capable of detecting and recognizing the activity of various deformation/transformation processes in NiTi and theoretically by micromechanical modeling. An earlier model of SMA polycrystal transformation is further developed, so it accounts for the strains due to the R-phase related deformation processes in activated NiTi. A continuous variation of the rhombohedral distortion angle α of the R-phase structure with temperature and stress is newly introduced as a legitimate deformation mechanism. Simulation results for NiTi bars and wires exposed to three types of thermomechanical tests—mechanical loading at constant temperature, cooling under constant stress, and recovery stress tests are presented and confronted with results.
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Sun, Tianyi, Jaehun Cho, Zhongxia Shang, Tongjun Niu, Jie Ding, Jian Wang, Haiyan Wang, and Xinghang Zhang. "Deformation mechanism in nanolaminate FeCrAl alloys by in situ micromechanical strain rate jump tests at elevated temperatures." Scripta Materialia 215 (July 2022): 114698. http://dx.doi.org/10.1016/j.scriptamat.2022.114698.
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Prasad, K. Nagendra, BR Srinivasa Murthy, A. Vatsala, and T. G. Sitharam. "Yielding of sensitive clays: micromechanical considerations." Canadian Geotechnical Journal 35, no. 1 (February 1, 1998): 169–74. http://dx.doi.org/10.1139/t97-072.
Abstract:
Test results reported on several natural sensitive soils show significant anisotropy of the yield curves, which are generally oriented along the coefficient of earth pressure at rest (K0) axis. An attempt is made in this paper to explain the anisotropy in yielding from microstructural considerations. An elliptic pore, with particle domains aligned along the periphery of the pore, and with the major axis of the pore being oriented along the direction of the in situ major principal stress, is chosen as the unit of microstructure. An analysis of forces at the interdomain contacts around the ellipse is carried out with reference to experimentally determined yield stress conditions of one soil, and a yield criteria is defined. The analysis, with the proposed yield criteria, enables one to define the complete yield curve for any other soil from the results of only two tests (one constant eta compression test with eta close to eta sub K0, where eta is the stress ratio (= q/p) and eta sub K0 is the stress ratio corresponding to anisotropic K0 compression, and another undrained shear test). Predicted yield curves are compared with experimental yield curves of several soils reported in the literature.Key words: sensitive clays, yield criteria, anisotropy, microstructure.
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Hu, Junfeng, Xi Deng, Xutong Zhang, Wen-Xue Wang, and Terutake Matsubara. "Effect of Off-Axis Ply on Tensile Properties of [0/θ]ns Thin Ply Laminates by Experiments and Numerical Method." Polymers 13, no. 11 (May 31, 2021): 1809. http://dx.doi.org/10.3390/polym13111809.
Abstract:
The effect of off-axis ply on the tensile properties of unbalanced symmetric [0/θ]ns laminates was explored through experimental and numerical analysis. Six CFRP [0/θ]2s plies with different off-axis angles θ were fabricated for tensile tests. In situ observations of the damage to the laminates were conducted to investigate the initiation and progressive growth of the laminates during the tension tests. The fiber fractures, crack initiation, and progressive propagation were analyzed by observing the free edge of the laminates, and the difference in damage behavior caused by different off-axis angles was investigated. All the six [0/θ]2s plies with off-axis angles θ ranging from 15° to 90° showed approximate linear stress–strain responses in the tensile tests. Matrix cracks were not observed prior to the final catastrophic failure in the off-axis layers of the [0/θ]2s laminates with a θ in the range of 15–60°. Finite element analysis (FEA) of the [0/θ]s plies was conducted using a 3D micromechanical model, in which matrix cracking and fiber-matrix debonding in the off-axis layer were simulated using a cohesive interface element. Three micromechanical crack-free, cohesive interface, and initial crack models were analyzed to predict the influence of the matrix cracks inside the off-axis layer on the damage behavior of the [0/θ]s laminates. The numerical results from the initial crack micromechanical model show a lower bound of the tensile strength of the [0/θ]s plies. A high stress concentration is observed adjacent to the cracked off-axis layer, inducing a tensile strength loss of about 20%.
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Alfreider, M., M. Meindlhumer, V. Maier-Kiener, A. Hohenwarter, and D. Kiener. "Extracting information from noisy data: strain mapping during dynamic in situ SEM experiments." Journal of Materials Research 36, no. 11 (January 19, 2021): 2291–304. http://dx.doi.org/10.1557/s43578-020-00041-0.
Abstract:
Abstract Micromechanical testing techniques can reveal a variety of characteristics in materials that are otherwise impossible to address. However, unlike to macroscopic testing, these miniaturized experiments are more challenging to realize and analyze, as loading and boundary conditions can often not be controlled to the same extent as in standardized macroscopic tests. Hence, exploiting all possible information from such an experiment seems utmost desirable. In the present work, we utilize dynamic in situ microtensile testing of a nanocrystalline equiatomic CoCrFeMnNi high entropy alloy in conjunction with initial feature tracking to obtain a continuous two-dimensional strain field. This enables an evaluation of true stress–strain data as well as of the Poisson’s ratio and allows to study localization of plastic deformation for the specimen. We demonstrate that the presented image correlation method allows for an additional gain of information in these sophisticated experiments over commercial tools and can serve as a starting point to study deformation states exhibiting more complex strain fields. Graphic abstract
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Shen, Yang, Thilo F. Morgeneyer, Jérôme Garnier, Lucien Allais, Lukas Helfen, and Jérôme Crépin. "Quantitative Anisotropic Damage Mechanism in a Forged Aluminum Alloy Studied by Synchrotron Tomography and Finite Element Simulations." Advances in Materials Science and Engineering 2019 (July 25, 2019): 1–12. http://dx.doi.org/10.1155/2019/8739419.
Abstract:
A highly anisotropic toughness behavior has been revealed on a forged AA6061 aluminum alloy by toughness tests with CT specimens. The toughness values with specimens loaded on the longitudinal direction are larger than that loaded on the transverse direction due to the anisotropic shape and distribution of coarse precipitates induced by the morphological anisotropy of grains during forging process. Synchrotron radiation computed tomography analysis on as-received material and arrested cracks revealed different fracture modes for the two loading configurations. The damage mechanism has been validated by finite element simulations based on the Gurson–Tvergaard–Needleman micromechanical damage model with different sets of damage parameters for the two loading configurations obtained from quantitative void volume fraction analysis on SRCT data, in situ SEM experiments, and SRCT microstructural analysis.
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Roscioli, Gianluca, Seyedeh Mohadeseh Taheri-Mousavi, and Cemal Cem Tasan. "How hair deforms steel." Science 369, no. 6504 (August 6, 2020): 689–94. http://dx.doi.org/10.1126/science.aba9490.
Abstract:
Steels for sharp edges or tools typically have martensitic microstructures, high carbide contents, and various coatings to exhibit high hardness and wear resistance. Yet they become practically unusable upon cutting much softer materials such as human hair, cheese, or potatoes. Despite this being an everyday observation, the underlying physical micromechanisms are poorly understood because of the structural complexity of the interacting materials and the complex boundary conditions of their co-deformation. To unravel this complexity, we carried out interrupted tests and in situ electron microscopy cutting experiments with two micromechanical testing setups. We investigated the findings analytically and numerically, revealing that the spatial variation of lath martensite structure plays the key role leading to a mixed-mode II-III cracking phenomenon before appreciable wear.
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Fiedler, Bodo, Stefan Holst, Thomas Hobbiebrunken, Masaki Hojo, and Karl Schulte. "Modelling of the Initial Failure of Cfrp Structures by Partial Discretisation: Amicro / Macro-Mechanical Approach of First Ply Failure." Advanced Composites Letters 13, no. 5 (September 2004): 096369350401300. http://dx.doi.org/10.1177/096369350401300501.
Abstract:
The formation of transverse matrix cracks is the early failure in carbon fibre reinforced composites (CFRP). Unidirectional laminates with 90° fibre orientation were tested by transverse tensile tests and in situ under 3 point bending load in the scanning electron microscope (SEM). Finite element analysis were carried on the microscopic level hexagonal unit cell of fibre and matrix, as on the macroscopic level based on homogenized fibre and matrix properties as well. To link the micromechanical approach with the homogenized description of composite structures was done by transferring boundary conditions from one model to the other. The influence of the temperature on the Young's modulus, the non-linear stress-strain behaviour and the strength of the matrix on the micro residual stresses and matrix failure was taken into account has been investigated in detail. Process induced thermal residual stresses and matrix failure of unidirectional carbon fibre reinforced composites (CFRP).
Dissertations / Theses on the topic "In-Situ micromechanical tests":
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Ezequiel, Alvarado Marco Alejandro. "Mécanismes de fragilisation d'alliages Cu-Zn par l'eutectique Ga-In." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR005.
Abstract:
Ce travail présente l'étude de la sensibilité à la fragilisation par les métaux liquides (FML) à température ambiante de laitons alpha contenant différents taux de zinc par l'eutectique liquide In-Ga (EGaIn). Le liquide EGaIn mouille le cuivre pur de manière partielle avec un angle de contact relativement faible de 49 ± 5 °. Cet angle est plus faible pour les laitons alpha et décroit avec le pourcentage en zinc. Il est de 36 ± 5 ° pour le laiton Cu-30%Zn. De plus, l'intermétallique CuGa2 se forme dès le contact avec le liquide EGaIn avec le cuivre et les laitons alpha, indépendamment de la teneur en zinc. Les essais de flexion 3 points montrent que la sensibilité à la FML par l'EGaIn augmente pour des vitesses de déformation élevées, des taux de zinc plus élévés et des duretés plus importantes. Dans les cas de FML, le liquide EGaIn n'affecte pas la phase d'initiation de la fissure mais seulement la propagation de la fissuration. En effet, les faciès de rupture présentent toujours une initiation ductile de la fissure puis une rupture fragile. L'intermétallique CuGa2 empêche l'initiation d'une rupture fragile en limitant le contact entre le métal liquide et le laiton dans les premières phases de l'essai mécanique. Puis l'intermétallique se fissure et ainsi, le liquide EGaIn rentre en contact avec le laiton rendant possible la FML à condition de déformations plastiques suffisamment importantes du laiton. A cause de l'initiation d'une rupture ductile, le laiton Cu-30%Zn ne présente pas de sensibilité à la FML lorsque il est testé par le small punch test (SPT) standard. Cependant l'utilisation d'échantillons de SPT pré-entaillés permet l'observation pour ce laiton de la FML en contact avec l'EGaIn liquide. De plus, du fait de l'initiation d'une rupture ductile, il est impossible à partir des résultats des essais de SPT et de flexion de déterminer une ténacité en présence de métal liquide. C'est pourquoi, des micro-essais de flexion avec observations in-situ et présence d'une couche fine protectrice de W ont été mis en oeuvre. Ils ont permis de déterminer en présence d'EGaIn liquide une ténacité de 1,57 ± 0.08 MPa m1/2 pour le laiton Cu-30%ZnThis work presents a study of the liquid metal embrittlement (LME) phenomenon at room temperature on alpha brasses with different Zn content in contact with the liquid eutectic Ga-In (EGaIn). The liquid EGaIn wets pure Cu partially with a relatively low contact angle of 49 ± 5 °, which is lower for the alpha brasses and decreases with the Zn content alloy down to 36 ± 5 ° for the Cu-30%Zn alloy. Moreover, the CuGa2 intermetallic forms whenever the liquid EGaIn is in contact with Cu and the alpha brasses, independently of the Zn content. Testing with the 3-point bending test showed that the LME sensitivity by the EGaIn increases at higher strain rates, higher Zn content, and higher hardness. Whenever there is LME, the liquid EGaIn does not affect the fracture initiation but the fracture propagation; hence the samples systematically presented a ductile fracture initiation followed by a brittle intergranular fracture propagation. The CuGa2 intermetallic impedes the brittle fracture initiation by blocking the contact between the EGaIn and the alpha brasses from the early stages of the test. Later, when the intermetallic breaks, the liquid EGaIn comes into contact with the alpha brass making the LME possible if the brass is under sufficient plastic deformation. Due to the ductile fracture initiation, the Cu-30%Zn alloy does not present LME when tested using the standard Small Punch Test (SPT). In contrast, using pre-notched SPT samples enables the observation of this alloy's embrittlement in contact with the liquid EGaIn. Furthermore, due to the ductile fracture initiation, it is impossible to use the bending tests or the SPT to measure the fracture toughness related to the LME phenomenon. In contrast, in-situ micro-bending tests with a W protective layer were suitable for the fracture toughness measurement of Cu-30%Zn in contact with the EGaIn; for instance, a fracture toughness value of 1.57 ± 0.08 MPa m1/2 was measured with the double clamped beam test
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Alia, Adem. "Comportement à la rupture d'un composite à fibres végétales." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI016.
Abstract:
L’objectif de cette thèse est la caractérisation du comportement mécanique et de l’endommagement d’un composite tissé jute/polyester. Les fibres végétales constituent en effet une alternative écologique intéressante à l’utilisation des fibres synthétiques, en particulier les fibres de verre qui sont les plus utilisées pour les pièces composites de grande diffusion. Le composite est développé au sein du laboratoire LMNM à l’IOMP, Sétif, Algérie. Deux orientations ([0]8 et [+45/-45]2S) sont considérées. La caractérisation mécanique est effectuée en traction et compression monotones ainsi qu’en fatigue cyclique. Les caractérisations mécaniques et microstructurales sont réalisées au sein du laboratoire MATEIS. L’étude de l’endommagement des composites est réalisée en combinant cinq techniques : l’évolution des paramètres mécaniques via des essais cyclés et de fatigue, la microscopie, l’émission acoustique (EA), la corrélation d’images et la micro-tomographie RX. L’étude de l’évolution des paramètres mécaniques accompagnée de l’analyse globale de l’EA fournit des premiers indicateurs quant au développement de l’endommagement lors des essais. Les analyses microstructurales permettent d’identifier finement les différents mécanismes d’endommagement qui surviennent lors des sollicitations mécaniques (décohésions fibre/matrice, fissurations matricielles et rupture de fibres). Pour la segmentation des signaux d’émission acoustique en traction et en compression monotones, une classification non-supervisée est utilisée en mettant l’accent sur le choix des descripteurs et sur la labellisation des classes obtenues. Des essais de traction instrumentés par corrélation d’images ainsi que des essais de traction in-situ sous tomographe permettent d’identifier la chronologie d’apparition de l’endommagement. Ces résultats permettent également de labelliser les classes obtenues. Les signaux labellisés servent ensuite à créer une bibliothèques pour identifier la chronologie d’évolution des modes d’endommagement en fatigue cyclique réalisée par classification supervisée. Enfin, toutes ces analyses ont permis d’établir des scénarios d’endommagement pour les différents modes d’endommagement et pour les deux orientations. Il est ainsi possible de reconsidérer l’élaboration pour optimiser les propriétés mécaniquesThe objective of this thesis is the characterization of the mechanical behavior and the damage of a woven jute / polyester composite. natural fibers are indeed an interesting ecological alternative to synthetic fibers, in particular glass fibers which are the most used for composite manufacturing. The studied composite is developed in the LMNM laboratory at IOMP, Sétif, Algeria. Two fibre orientations ([0] 8 and [+ 45 / -45] 2S) are considered. The mechanical characterization is carried out in monotonic tensile and compression as well as in cyclic fatigue. Mechanical and microstructural characterizations are carried out in the MATEIS laboratory. The study of the damage is carried out by combining five techniques: the evolution of mechanical parameters via cyclic and fatigue tests, microscopy, acoustic emission (EA), image correlation and micro- RX tomography. The study of the evolution of the mechanical parameters combined with the global analysis of the AE provides first indicators concerning the development of the damage during the tests. Microstructural analyzes allow to finely identify the damage mechanisms that occur during mechanical tests (fiber / matrix decohesions, matrix cracks and fiber breakage). For the segmentation of acoustic emission signals in monotonic tests, an unsupervised classification is used, emphasizing the choice of descriptors and the labeling of the classes obtained. Tensile tests instrumented by image correlation as well as in situ tensile tests under tomography allow to identify the chronology of appearance of the damage. These results are also used to label the obtained classes . The labeled signals are then used to create a library to identify the chronology of evolution of the modes of damage in cyclic fatigue achieved by supervised classification. Finally, all these analyzes made it possible to establish damage scenarios for the different damage modes and for the two orientations. It is thus possible to reconsider the development to optimize the mechanical properties
Conference papers on the topic "In-Situ micromechanical tests":
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Luo, W., C. Kirchlechner, G. Dehm, and F. Stein. "Micromechanics of Co-Nb Laves Phases: Strength, Fracture Toughness, and Hardness as Function of Composition and Crystal Structure." In AM-EPRI 2019, edited by J. Shingledecker and M. Takeyama. ASM International, 2019. http://dx.doi.org/10.31399/asm.cp.am-epri-2019p0011.
Abstract:
Abstract Laves phases are intermetallic phases well known for their excellent strength at high temperatures but also for their pronounced brittleness at low temperatures. Especially in high-alloyed steels, Laves phases were long time regarded as detrimental phases as they were found to embrittle the material. Perusing the more recent literature, it seems the negative opinion about the Laves phases has changed during the last years. It is reported that, if the precipitation morphology is properly controlled, transition metal-based Laves phases can act as effective strengthening phases in heat resistant steels without causing embrittlement. For a targeted materials development, the mechanical properties of pure Laves phases should be known. However, the basic knowledge and understanding of the mechanical behavior of Laves phases is very limited. Here we present an overview of experimental results obtained by micromechanical testing of single-crystalline NbCo2 Laves phase samples with varying crystal structure, orientation, and composition. For this purpose, diffusion layers with concentration gradients covering the complete homogeneity ranges of the hexagonal C14, cubic C15 and hexagonal C36 NbCo2 Laves phases were grown by the diffusion couple technique. The hardness and Young's modulus of NbCo2 were probed by nanoindentation scans along the concentration gradient. Single-phase and single crystalline microcantilevers and micropillars of the NbCo2 Laves phase with different compositions were cut in the diffusion layers by focused ion beam milling. The fracture toughness and the critical resolved shear stress (CRSS) were measured by in-situ microcantilever bending tests and micropillar compression tests, respectively. The hardness, Young's modulus and CRSS are nearly constant within the extended composition range of the cubic C15 Laves phase, but clearly decrease when the composition approaches the boundaries of the homogeneity range where the C15 structure transforms to the off stoichiometric, hexagonal C36 and C14 structure on the Co-rich and Nb-rich, respectively. In contrast, microcantilever fracture tests do not show this effect but indicate that the fracture toughness is independent of crystal structure and chemical composition of the NbCo2 Laves phase.
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CUI, XIAODONG, JIAN XIAO, JIM LUA, SUPUN KARIYAWASAM, ETHAN FULGHUM, CALEB SAATHOFF, and WARUNA SENEVIRATNS. "A MULTISCALE MODELING AND X-RAY CT EXPLORATION OF BEARING FAILURE MECHANISMS IN A COUNTERSUNK BOLTED COMPOSITE STRUCTURE." In Thirty-sixth Technical Conference. Destech Publications, Inc., 2021. http://dx.doi.org/10.12783/asc36/35879.
Abstract:
To investigate the failure mechanism in composite bolted joints, an in-situ X-Ray computed tomography (XCT) technique was developed and single shear bearing (SSB) tests were performed with quasi-isotropic layup. High-fidelity XCT was explored for the detection and characterization of bearing failure in bolted composite components without removing the fastener. A novel load frame was also introduced for in-situ XCT scan and a preliminary scan was performed. A micro-macro coupling modeling approach was proposed on the basis of continuum damage mechanics (CDM) method and a static bearing model, which was based on micromechanics analysis to consider the residual stress after fiber kinking and matrix cracking under compression in the bearing region. The SSB specimens were modified using a larger bolt diameter to avoid bolt failure and achieve extensive bearing failure. The developed modeling approach was verified using SSB test data by comparing the predicted load displacement response with experimental measurement and the failure patterns obtained from XCT scanning images.
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Heyn, Wieland, Hanno Melzner, Klaus Goller, Sergey Ananiev, Andre Clausner, Johannes Zechner, and Ehrenfried Zschech. "In-situ SEM micromechanical experiments on Dual Damascene Copper test structures for investigation of interfacial properties of copper interconnects." In 2021 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA). IEEE, 2021. http://dx.doi.org/10.1109/ipfa53173.2021.9617276.
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Chulya, Abhisak, John P. Gyekenyesi, and Ramakrishna T. Bhatt. "Mechanical Behavior of Fiber Reinforced SiC/RBSN Ceramic Matrix Composites: Theory and Experiment." In ASME 1991 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1991. http://dx.doi.org/10.1115/91-gt-209.
Abstract:
The mechanical behavior of continuous fiber reinforced SiC/RBSN composites with various fiber contents is evaluated. Both catastrophic and noncatastrophic failures are observed in tensile specimens. Damage and failure mechanisms are identified via in-situ monitoring using NDE techniques throughout the loading history. Effects of fiber/matrix interface debonding (splitting) parallel to the fibers are discussed. Statistical failure behavior of fibers is also observed, especially when the interface is weak. Micromechanical models incorporating residual stresses to calculate the critical matrix cracking strength, ultimate strength and work of pull-out are reviewed and used to predict composite response. For selected test problems, experimental measurements are compared to analytical predictions.
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Koulidis, Alexis, Fahd Mohamed, and Shehab Ahmed. "Micromechanics of Drilling: A Laboratory Investigation of Formation Evaluation at the Bit." In SPE Middle East Oil & Gas Show and Conference. SPE, 2021. http://dx.doi.org/10.2118/204670-ms.
Abstract:
Abstract Challenging drilling applications and low oil prices have created a new emphasis on innovation in the industry. This research investigates the value of drill bit based force sensing at the rock-cutter interface. For this purpose, a laboratory-based mini-rig has been built in order to recreate a scaled drilling process. The work aims to build a better understanding of the collected force and torque data despite the semi-continuous drilling process. This data is then used to estimate the formation strength. A scaled drill bit with two cutters was designed with sensors integrated into the drill bit cutter, drill string and the mini-rig structure. The mini-rig design allowed the accurate control of depth of cut by utilizing a comprehensive data acquisition and control system during the experiments. Initially, fifty-five samples were prepared with various water/gypsum ratios for a uniaxial compression test, scratch test, and for testing in the mini-rig. Prior to the mini-rig experiments, the results of the uniaxial compression and scratch tests were used as a benchmark to extract rock properties and the state of stress behavior. The experiments under atmospheric conditions revealed that the mini-rig could accurately estimate formation strength from a few rotations. The force data at the bit-rock interface was correlated with the torque measurements, and the results indicate that the tangential force has similar trends and relatively similar values. The groove created by the drill bit's rotating trajectory has a 14.45 cm circumference. This allows for a significant amount of data to be captured from a single rotation. The circular cutter geometry's influence is crucial for a continuous process since the active cutting area is continuously changing due to the pre-cut groove. The performed depth of cuts ranged from 0.1 to 1 mm in the same groove, and thus the active cutting area can be accurately calculated in real-time while conducting the experiments. Tangential and normal force data from the scratch test was analyzed in order to provide insights for correlation with the mini-rig data. The analysis shows that both tests give similar trends to the force measurements from the mini-rig. Moreover, the benchmark value of formation strength that was obtained from the uniaxial compression test was also in the same range. This illustrates the potential viability of drill bit based formation strength measurement due to the similarity between mini-rig test results and those using more classical testing practices. The experimental setup can provide a continuous cutting process that allows an accurate estimation of formation strength during a semi-continuous drilling operation with analogous application in the field. This can lead to an in-depth understanding of drilled formation properties while drilling and possibly assist in evaluating cutter wear state in-situ.
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RAPKING, DANIEL, LUKE GEISE, ROBERT WHEELER, and MARK FLORES. "DEVELOPMENT OF SINGLE CASE STUDIES FOR MICROMECHANICS DAMAGE EVOLUTION IN UNIDIRECTIONAL COMPOSITES." In Proceedings for the American Society for Composites-Thirty Seventh Technical Conference. Destech Publications, Inc., 2022. http://dx.doi.org/10.12783/asc37/36433.
Abstract:
This study continues to further expand the methods utilized by the Air Force Research Laboratory (AFRL) to understand microscale damage evolution. The microscale test data collected here will be used to validate many multiscale modeling frameworks’ ability to accurately predict damage evolution in complex, heterogeneous microscale structures. Previous work has conducted testing of transverse compression (TC) pillars in scanning electron microscope (SEM) load stages allowing for the measurement of surface level strains while being loaded. The limitation of this approach is a lack of understanding how damage develops through the thickness of the pillar during loading. This work involved the fabrication of a transverse compression micropillar and the experimental test of this sample that visualized through thickness damage evolution in-situ. A post mortem tomography was conducted to fully analyze damage evolution in the micro-pillar to validate the planned framework would be viable for additional microstructural geometries. A complete examination of the pillar, a postmortem Nano-CT, and a preliminary methodology for evaluating multiscale models are presented within this work.