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Articoli di riviste sul tema "Tensile tests. nanoindentation"
1
Abdullah, Izhan, Muhammad Nubli Zulkifli, Azman Jalar e R. Ismail. "Deformation behavior relationship between tensile and nanoindentation tests of SAC305 lead-free solder wire". Soldering & Surface Mount Technology 30, n. 3 (4 giugno 2018): 194–202. http://dx.doi.org/10.1108/ssmt-07-2017-0020.
Testo completoAbstract (sommario):
PurposeThe relationship between the bulk and localized mechanical properties is critically needed, especially to understand the mechanical performance of solder alloy because of smaller sizing trend of solder joint. The purpose of this paper is to investigate the relationship between tensile and nanoindentation tests toward the mechanical properties and deformation behavior of Sn-3.0Ag-0.5Cu (SAC305) lead-free solder wire at room temperature.Design/methodology/approachTensile test with different strain rates of 1.5 × 10-4 s-1, 1.5 × 10-3 s-1, 1.5 × 10-2 s-1 and 1.5 × 10-1 s-1 at room temperature of 25°C were carried out on lead-free Sn-3.0Ag-0.5Cu (SAC305) solder wire. Stress–strain curves and mechanical properties such as yield strength (YS), ultimate tensile strength (UTS) and elongation were determined from the tensile test. Load-depth (P-h) profiles and micromechanical properties, namely, hardness and reduced modulus, were obtained from nanoindentation test. In addition, the deformation mechanisms of SAC305 lead-free solder wire were obtained by measuring the range of creep parameters, namely, stress exponent and strain rate sensitivity, using both of tensile and nanoindentation data.FindingsIt was observed that qualitative results obtained from tensile and nanoindentation tests can be used to identify the changes of the microstructure. The occurrence of dynamic recrystallization and the increase of ductility obtained from tensile test can be used to indicate the increment of grain refinement or dislocation density. Similarly, the occurrence of earliest pop-in event and the highest occurrence of pop-in event observed from nanoindentation also can be used to identify the increase of grain refinement and dislocation density. An increment of strain rates increases the YS and ultimate UTS of SAC305 solder wire. Similarly, the variation of hardness of SAC305 solder wire has the similar trend or linear relationship with the variation of YS and UTS, following the Tabor relation. In contrast, the variation of reduced modulus has a different trend compared to that of hardness. The deformation behavior analysis based on the Holomon’s relation for tensile test and constant load method for nanoindentation test showed the same trend but with different deformation mechanisms. The transition of responsible deformation mechanism was obtained from both tensile and nanoindentation tests which from grain boundary sliding (GBS) to grain boundary diffusion and dislocation climb to grain boundary slide, respectively.Originality/valueFor the current analysis, the relationship between tensile and nanoindentation test was analyzed specifically for the SAC305 lead-free solder wire, which is still lacking. The findings provide a valuable data, especially when comparing the trend and mechanism involved in bulk (tensile) and localized (nanoindentation) methods of testing.
2
Němeček, Jiří, e Jiří Němeček. "Microscale Tests of Cement Paste Performed with FIB and Nanoindentation". Key Engineering Materials 760 (gennaio 2018): 239–44. http://dx.doi.org/10.4028/www.scientific.net/kem.760.239.
Testo completoAbstract (sommario):
This study deals with experimental determination of tensile properties of cement paste hydration products at micro-scale. Cantilever micro-beams with length of about 16 µm and pentagon cross section with micrometer dimensions were fabricated by focused ion beam milling on hydrated cement paste samples. Nanoindentation was used for evaluating elastic properties while tensile properties were derived from beam bending tests. Displacement controlled micro-scale tests give access to both tensile strength and estimates of fracture energy based on the load-displacement curves measured with the nanoindenter. The mean tensile strength and the fracture energy of inner hydration product were assessed as 791 MPa and 16.7 J/m2, respectively. The huge difference of the micro-scale properties when compared to macroscopic values comes from the scaling properties of concrete.
3
Bencomo-Cisneros, J. A., A. Tejeda-Ochoa, J. A. García-Estrada, C. A. Herrera-Ramírez, A. Hurtado-Macías, R. Martínez-Sánchez e J. M. Herrera-Ramírez. "Characterization of Kevlar-29 fibers by tensile tests and nanoindentation". Journal of Alloys and Compounds 536 (settembre 2012): S456—S459. http://dx.doi.org/10.1016/j.jallcom.2011.11.031.
Testo completo
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Němeček, Jiří. "Nanoindentation Applied to Materials with an Inner Structure". Key Engineering Materials 586 (settembre 2013): 55–58. http://dx.doi.org/10.4028/www.scientific.net/kem.586.55.
Testo completoAbstract (sommario):
Nowadays, nanoindentation is commonly applied to various materials to assess micromechanical properties. Often, exact microstructure of the material building blocks is not properly analyzed which may introduce large discrepancies in the data obtained from different tests. It is shown in the paper, that different deformation mechanisms in tension and compression take place for the tested materials which is demonstrated by large differences between the measured nanoindentation moduli and macroscopic tensile elastic moduli. The situation is illustrated on several types of biological and man-made fibers. Differences ~44-57% in elastic moduli evaluated from the two tests appear in case of biological fibers, ~68% difference was found for high strength PVA fibers and 767% (!) for carbon fibers.
5
Long, Xu, Xiaodi Zhang, Wenbin Tang, Shaobin Wang, Yihui Feng e Chao Chang. "Calibration of a Constitutive Model from Tension and Nanoindentation for Lead-Free Solder". Micromachines 9, n. 11 (20 novembre 2018): 608. http://dx.doi.org/10.3390/mi9110608.
Testo completoAbstract (sommario):
It is challenging to evaluate constitutive behaviour by using conventional uniaxial tests for materials with limited sizes, considering the miniaturization trend of integrated circuits in electronic devices. An instrumented nanoindentation approach is appealing to obtain local properties as the function of penetration depth. In this paper, both conventional tensile and nanoindentation experiments are performed on samples of a lead-free Sn–3.0Ag–0.5Cu (SAC305) solder alloy. In order to align the material behaviour, thermal treatments were performed at different temperatures and durations for all specimens, for both tensile experiments and nanoindentation experiments. Based on the self-similarity of the used Berkovich indenter, a power-law model is adopted to describe the stress–strain relationship by means of analytical dimensionless analysis on the applied load-penetration depth responses from nanoindentation experiments. In light of the significant difference of applied strain rates in the tensile and nanoindentation experiments, two “rate factors” are proposed by multiplying the representative stress and stress exponent in the adopted analytical model, and the corresponding values are determined for the best predictions of nanoindentation responses in the form of an applied load–indentation depth relationship. Eventually, good agreement is achieved when comparing the stress–strain responses measured from tensile experiments and estimated from the applied load–indentation depth responses of nanoindentation experiments. The rate factors ψ σ and ψ n are calibrated to be about 0.52 and 0.10, respectively, which facilitate the conversion of constitutive behaviour from nanoindentation experiments for material sample with a limited size.
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Li, Cong, Hongwei Zhao, Linlin Sun e Xiujuan Yu. "In situ nanoindentation method for characterizing tensile properties of AISI 1045 steel based on mesomechanical analysis". Advances in Mechanical Engineering 11, n. 7 (luglio 2019): 168781401986291. http://dx.doi.org/10.1177/1687814019862919.
Testo completoAbstract (sommario):
A novel method for characterizing the tensile properties of AISI 1045 steel is proposed by combining the method of in situ nanoindentation test and the theory of mesomechanical analysis. First, the load–depth curves of exact location of ferrite, pearlite and grain boundary on the surface of AISI 1045 steel are obtained by 30 groups of in situ nanoindentation tests. The constitutive equation (stress–strain function) of the real-time metallographic structure is obtained by nanoindentation analysis of the above curves. Then, based on the principle of mesomechanical analysis, the computational representative volume element models are reconstructed according to the three metallographic images of AISI 1045 steel surface collected by the test equipment. Finally, taking the constitutive equation of the real-time metallographic structure as the input condition, the finite element analysis of the above representative volume element models are carried out. The data resulted from finite element analysis are taken as the tensile mechanical properties of AISI 1045 steel. The elastic modulus of AISI 1045 steel calculated is as the same as that by the traditional nanoindentation method. And, the error is less than 6% compared with the tensile test, which is within the range of the elastic modulus of the material. The error between the yield strength calculated and tensile test results is 3.4%. Due to the influence of surface cracks on the plastic deformation ability of AISI 1045 steel during tension, the error between the strain hardening index calculated and tensile test results is 7.4%. The results show that it is a more accurate nondestructive testing method in the point of material damage mechanism. On the premise of using more accurate representative volume element modelling way, this method is suitable for testing more materials.
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Lofaj, Frantisek, e Dušan Németh. "FEM of Cracking during Nanoindentation and Scratch Testing in the Hard W-C Coating/Steel Substrate System". Key Engineering Materials 784 (ottobre 2018): 127–34. http://dx.doi.org/10.4028/www.scientific.net/kem.784.127.
Testo completoAbstract (sommario):
Finite element modelling (FEM) and eXtended FEM (XFEM) combined with the experimental nanoindentation and scratch tests have been used to simulate the process of cohesive cracking in W-C coating on softer and more ductile steel substrate during nanoindentation and scratch testing. The formation of single and multiple circular “frame” cohesive cracks in the sink-in zone during nanoindentation were explained by the development of high local tensile stresses in the coatings controlled by the plastic deformation of the substrate. Analogous mechanisms were successfully applied to the simulation of multiple Chevron type cracking during scratch testing. Thus, the ability of XFEM to predict the formation of different types of cohesive cracks was confirmed. It was also demonstrated that both nanoindentation and scratch tests in combination with XFEM can be used as the methods to determine the strength and fracture toughness of thin coatings.
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Němeček, Jiří, Jan Maňák, Tomáš Krejčí e Jiří Němeček. "Small scale tests of cement with focused ion beam and nanoindentation". MATEC Web of Conferences 310 (2020): 00053. http://dx.doi.org/10.1051/matecconf/202031000053.
Testo completoAbstract (sommario):
Nanoindentation is used for characterization of small scale material properties of hydrated cement. It is employed as a precise loading tool on samples fabricated with Focused Ion Beam milling (FIB). The effect of heat on the microstructure of cement during different FIB energy loads is studied. Milling currents as low as 0.1 nA can be considered as save and not damaging. Micrometer sized beams were bent to reveal strength and fracture characteristics. Small scale elastic properties, tensile strength and fracture energy of individual low scale microstructural constituents of cement paste like C-S-H rich phases and Portlandite were assessed. Very high tensile strengths at the micrometer scale were observed for cement paste hydration products (200-700 MPa) with fracture energies 4-20 J/m2 The results are consistent with atomistic simulations and multi-scale modeling from available literature.
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Veleva, Lyubomira, Peter Hähner, Andrii Dubinko, Tymofii Khvan, Dmitry Terentyev e Ana Ruiz-Moreno. "Depth-Sensing Hardness Measurements to Probe Hardening Behaviour and Dynamic Strain Ageing Effects of Iron during Tensile Pre-Deformation". Nanomaterials 11, n. 1 (30 dicembre 2020): 71. http://dx.doi.org/10.3390/nano11010071.
Testo completoAbstract (sommario):
This work reports results from quasi-static nanoindentation measurements of iron, in the un-strained state and subjected to 15% tensile pre-straining at room temperature, 125 °C and 300 °C, in order to extract room temperature hardness and elastic modulus as a function of indentation depth. The material is found to exhibit increased disposition for pile-up formation due to the pre-straining, affecting the evaluation of the mechanical properties of the material. Nanoindentation data obtained with and without pre-straining are compared with bulk tensile properties derived from the tensile pre-straining tests at various temperatures. A significant mismatch between the hardness of the material and the tensile test results is observed and attributed to increased pile-up behaviour of the material after pre-straining, as evidenced by atomic force microscopy. The observations can be quantitatively reconciled by an elastic modulus correction applied to the nanoindentation data, and the remaining discrepancies explained by taking into account that strain hardening behaviour and nano-hardness results are closely affected by dynamic strain ageing caused by carbon interstitial impurities, which is clearly manifested at the intermediate temperature of 125 °C.
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Lofaj, František, Dušan Németh, Rudolf Podoba e Michal Novák. "Cracking in Brittle Coatings during Nanoindentation". Key Engineering Materials 662 (settembre 2015): 103–6. http://dx.doi.org/10.4028/www.scientific.net/kem.662.103.
Testo completoAbstract (sommario):
The FIB/SEM investigations of the microstructure changes in the hard brittle W-C based coating deposited on softer steel substrate after nanoindentation tests revealed that a set of approximately equidistant circular cracks forms in the coating in a sink-in zone around the indent and single cracks appear under the indenter tip. Finite element modeling (FEM) indicated development and concentration of the highest principal tensile stresses in the sink-in zone and in the zone below the indenter, which are considered to be the reason for the experimentally observed cracking. The distance from the indenter tip to the first circular crack combined with the calibration curve obtained from the FEM of the location of tensile stress maxima in sink-in zone can be used as a simple method for the determination of the strength of the studied coatings.
Tesi sul tema "Tensile tests. nanoindentation"
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Gasmi, Assia. "Effet de la nanostructuration sur le comportement thermomécanique du Nitinol". Electronic Thesis or Diss., Université de Montpellier (2022-....), 2024. http://www.theses.fr/2024UMONS018.
Testo completoAbstract (sommario):
La présente thèse s’intéresse à l'alliage à mémoire de forme NiTi, en se concentrant sur l'influence du procédé de nanostructuration superficielle SMAT sur son comportement thermomécanique. À travers quatre chapitres distincts, elle rappelle les principales caractéristiques des alliages à mémoire de forme (AMF), mettant en avant les propriétés exceptionnelles de l'alliage NiTi, et explorant le traitement de nanocristallisation superficielle (SMAT). La caractérisation microstructurale est ensuite approfondie, notamment en étudiant les effets du traitement thermique de recuit et du SMAT sur la transition de phase. Le troisième chapitre se concentre sur les méthodes d'analyse thermomécanique adaptées au NiTi, en examinant les essais de traction et de nanoindentation. Enfin, le quatrième chapitre analyse la caractérisation thermomécanique de l'alliage avant et après le traitement SMAT, mettant en évidence les implications de ces transformations sur son comportement global.La thèse contribue à la compréhension des effets du procédé SMAT sur l'alliage NiTi, révélant des liens entre la microstructure, les phases présentes et les propriétés mécaniques. Les résultats ouvrent des perspectives prometteuses pour la meilleure maîtrise des propriétés de l'alliage NiTi.Les résultats obtenus pour différents traitements SMAT montrent que ce procédé modifie la réponse mécanique du matériau. Elle a aussi une influence sur son état initial, comme l’illustrent les différences dans les courbes de DSC. Les mesures cinématiques (champs de vitesses de déformation) et calorimétriques (champ de source de chaleur) indiquent aussi l’apparition de différences notables dans les réponses en fonction des paramètres de traitement SMAT. L'exploration du comportement lors de cycles de charge/décharge montre une réponse qui se stabiliser après quelques cycles. Les effets de couplage semblent être prépondérants par rapport aux effets dissipatifs. Ces observations devraient être étendues à des chargements en fatigue afin de mieux mettre en évidence les éventuels effets dissipatifs. De même, l’utilisation de modèles d’interprétation plus élaborés permettrait de mieux tenir compte des effets de structure et d’enrichir la compréhension de la relation entre le procédé et les évolutions des propriétésThis thesis focuses on the shape memory alloy NiTi, with a specific emphasis on the influence of the surface nanostructuring process SMAT on its thermomechanical behavior. Through four distinct chapters, it revisits the main characteristics of shape memory alloys (SMAs), highlighting the exceptional properties of the NiTi alloy and exploring the surface nanocrystallization treatment (SMAT). Microstructural characterization is then deeply investigated, particularly by studying the effects of annealing heat treatment and SMAT on phase transition. The third chapter focuses on thermomechanical analysis methods suitable for NiTi, examining tensile tests and nanoindentation. Finally, the fourth chapter analyzes the thermomechanical characterization of the alloy before and after SMAT treatment, highlighting the implications of these transformations on its overall behavior.This thesis contributes to understanding the effects of the SMAT process on the NiTi alloy, revealing links between microstructure, present phases, and mechanical properties. The results offer promising perspectives for better control of the properties of the NiTi alloy.The results obtained for different SMAT treatments show that this process modifies the mechanical response of the material. It also has an influence on its initial state, as illustrated by differences in DSC curves. Kinematic (strain rate fields) and calorimetric (heat source field) measurements also indicate notable differences in responses depending on SMAT processing parameters. Exploration of behavior during load/unload cycles shows a response that stabilizes after a few cycles. Coupling effects seem to be predominant compared to dissipative effects. These observations should be extended to fatigue loading to better highlight any dissipative effects. Similarly, the use of more elaborate interpretation models would allow better consideration of structural effects and enrich the understanding of the relationship between the process and property evolutions
2
Abdel-Wahab, Adel A. "Experimental and numerical analysis of deformation and fracture of cortical bone tissue". Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8790.
Testo completoAbstract (sommario):
Bones are the principal structural components of a skeleton; they provide the body with unique roles, such as its shape maintenance, protection of internal organs and transmission of muscle forces among body segments. Their structural integrity is vital for the quality of life. Unfortunately, bones can only sustain loads until a certain limit, beyond which it fails. Usually, the reasons for bone fracture are traumatic falls, sports injuries, and engagement in transport or industrial accidents. The stresses imposed on a bone in such activities can be far higher than those produced during normal daily activities and lead to fracture. Understanding deformation and fracture behaviours of bone is necessary for prevention and diagnosis of traumas. Even though, in principle, studying bone's deformation and fracture behaviour is of immense benefit, it is not possible to engage volunteers in in-vivo investigations. Therefore, by developing adequate numerical models to predict and describe its deformation and fracture behaviours, a detailed study of reasons for, and ways to prevent or treat bone fracture could be implemented. Those models cannot be formulated without a set of experimental material data. To date, a full set of bone's material data is not implemented in the material data-base of commercial finiteelement (FE) software. Additionally, no complete set of data for the same bone can be found in the literature. Hence, a set of cortical bone's material data was experimentally measured, and then introduced into the finite-element software. A programme of experiments was conducted to characterise mechanical properties of the cortical bone tissue and to gain a basic understanding of the spatial variability of those properties and their link to the underlying microstructure. So, several types of experiments were performed in order to quantify mechanical properties of the studied bone tissue at macro- and microscales under quasi-static and dynamic loading regimes for different cortex positions called anterior, posterior, medial and lateral. Those experiments included: (1) uniaxial tension and creep tests to obtain its elastic, plastic and viscoelastic properties; (2) nanoindentation tests to characterise its microstructural elastic-plastic properties; (3) Izod tests to investigate its fracture properties under impact bending loading; (4) tensile-impact tests to characterise its impact strength and fracture force when exposed to a longitudinal loading regime. All the experiments were performed for different cortex positions and different directions (along the bone axis and perpendicular to it) when possible. Based on the results of those experiments, a number of finite-element models were developed in order to analyse its deformation and fracture using the extended finiteelement method (X-FEM) at different length scales and under various loading conditions. Those models included: (1) two-dimensional (2D) FE models to simulate its fracture and deformation at microscale level under quasi-static tensile loading. Additionally, the effect of the underlying microstructure on crack propagation paths was investigated; (2) 2D and three-dimensional (3D) FE models to simulate its fracture and deformation at macroscale level for the Izod impact test setup. In addition, the applicability of different constitutive material models was examined; (3) 3D FE models to simulate its fracture and deformation at macroscale level for tensile-impact loading conditions. The developed models provided high-quality results, and most importantly, they adequately reflected the experimental data. The main outcome of this thesis is a comprehensive experimental analysis and numerical simulations of the deformation and fracture of the cortical bone tissue at different length scales in response to quasi-static and dynamic loading. Recommendations on further research developments are also suggested.
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Wu, Chung Lin, e 吳忠霖. "Study of Bulge Test, Nano Tensile Tester, and Nanoindentation System for Mechanical Properties Measurement of Thin Films". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/35286258751227527601.
Testo completoAbstract (sommario):
博士國立清華大學
動力機械工程學系
97
The bulge test is a convenient approach to determine the thin film mechanical properties. This study presents a fabrication process to prepare the circular membrane made of metal as well as dielectric films for bulge test. The process successfully combines the dry etching of DRIE and XeF2 to release the test metal films. The Si3N4 film is used to protect the metal layers during the release process. By changing the recipe of XeF2 etching, the circular Si3N4 test membrane can also be fabricated. In applications, the circular membranes of Al, Au, and Si3N4 films were successfully prepared using the present approach. By using these specimens, the bulge test designed in this work was used to determine the thin film Young's modulus. The results by the bulge test show the similar trend with the results obtained by nanoindentation test. To find out the measurement ability of force and displacement of nano tensile tester and nanoindentation system, we adopted the method suggested in ISO GUN to calculate the uncertainty of this system. The standard weights are used to calibrate the force of the testing system. In addition, an optical method is adopted to evaluate the displacement uncertainty of the system. This research can be used as the basis for calculating measurement uncertainty in performing material tests. Moreover, this study is to investigate the static and dynamic mechanical properties of polydimethylsiloxane (PDMS) and the mixture of PDMS and carbon nanotubes. The PDMS/CNTs nanocomposites were stirred by an ultrasonic instrument to prevent agglomerations. A calibrated nano tensile tester was adopted in this testing system with maximum load of 500 mN and crosshead extension of 150 mm. The dynamic properties of PDMS/CNTs nanocomposites such as storage and loss modulus can be obtained by this system. The storage modulus increased with the CNTs content and also with the higher frequencies. Finally, the nanoindentation measurement system was employed to characterize the mechanical properties of PDMS and PDMS/CNTs. The increase of Young’s modulus by nanoindentation test has the similar trend with the results obtained by the tensile test method.
Atti di convegni sul tema "Tensile tests. nanoindentation"
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Tillmann, W., U. Selvadurai e W. Luo. "Measurement of the Young’s Modulus of Thermal Spray Coatings by Means of Several Methods". In ITSC 2012, a cura di R. S. Lima, A. Agarwal, M. M. Hyland, Y. C. Lau, C. J. Li, A. McDonald e F. L. Toma. ASM International, 2012. http://dx.doi.org/10.31399/asm.cp.itsc2012p0580.
Testo completoAbstract (sommario):
Abstract Thermally sprayed coatings are usually defined by their hardness, porosity, roughness and wear resistance. Even though the Young’s modulus is an essential property, which describes the mechanical behavior of the coated components during their use, only few efforts were made to determine this property. The most common measurement methods of the Young’s modulus of thermally sprayed coatings are tensile tests, bending tests, and nanoindentations. During the tensile and bending tests a sliding of the splats can occur due to the laminar structure of the thermally sprayed coatings, influencing the measurement value. When using the nanoindentation test, only the elastic behavior of a single splat can be determined because of a minimal measuring volume. However, the Young’s Modulus of thermally sprayed coatings can also be determined by means of a resonant method, called impulse excitation technique (IET). In this paper, the values of the Young’s moduli of thermally sprayed coatings, measured by several methods are compared with each other and correlated to the microstructure of the coatings, investigated by means of scanning electron microscopy.
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Ovaert, Timothy C., e B. R. Kim. "Estimation of Polymer Coating Scratch Tensile Strength by Nano-Indentation, Micro-Scratch Testing, and Finite Element Modeling". In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63700.
Testo completoAbstract (sommario):
In a previous paper, polymer coating viscoelastic/plastic properties were determined using nanoindentation and the finite element method. In this work, the individual layers, once characterized, were assembled into a multi-layered structure and subject to micro-scratch tests. These tests determined a critical scratch indentation load for the layered structure, as designated by the first appearance during scratching of visible surface layer tensile cracks. Scratch tests were carried out for three different conical scratch tip radii. The top-layer tensile strength of the layered structures was then estimated, utilizing the individual layer properties, the top layer friction coefficients, the micro-scratch test critical loads, and a finite element scratch model, for each scratch tip radius. The values of the top layer scratch tensile strengths were in good agreement for each of the three tip radii, as anticipated. The top-layer scratch tensile strengths may be utilized for further analysis and comparison of differences in gloss retention after gloss reduction experiments. The method may be used as a basis for coating selection, comparison, and performance testing in scratch-resistant polymer coating applications.
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Tew, J. W. R., J. Wei, Y. F. Sun, F. Su e Y. C. Liu. "Thermomechanical and Creep Behaviours of Au/Sn Solder Alloy". In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-13242.
Testo completoAbstract (sommario):
Au/Sn eutectic solder alloy is particularly attractive for high-power electronics and optoelectronics packaging as hermetic sealing and die attachment material. The robustness and reliability of solder joint are essential to meet the global demand for longer operating lifetime in their applications. The mechanical response of Au/Sn solder alloy is studied using nanoindentation (Nano-Test 600). Miniature creep samples were created using a specially designed fixture and static loading creep tests were carried out on these solder samples at temperatures of 25°C, 75°C and 125°C using tensile testing machine (Micro-Testing System). The Young's Modulus and hardness of 80Au/20Sn solder alloy increase with an increase in load rate or a decrease in temperature. The microstructure and creep rupture fractography of 80Au/20Sn solder alloy have been observed and analysed.
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Kwak, Dong-Hyeon, Jae Min Sim, Yoon-Suk Chang, Byeong Seo Kong e Changheui Jang. "Determination of Irradiated Stainless Steel Properties and Its Effects on Reactor Vessel Internals". In ASME 2022 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/pvp2022-84936.
Testo completoAbstract (sommario):
Abstract Reactor vessel internals (RVIs) consist of austenitic stainless steels (ASSs) which have excellent material properties. Meanwhile, the high radiation environment of a reactor can cause the degradation of components. Since changed material properties are important for long-term operation, experimental researches related to tensile and fracture properties had been conducted. However, it is limited to investigate these researches due to their high radioactivity and small quantity. Thus recent researches have been dedicated to small specimens such as nanoindentation and micropillar compression tests and so on with ion-irradiation. In this study, micropillar compression tests were carried out for virgin and irradiated 304 ASSs to obtain microscopic mechanical behaviors. The trial sets of finite element (FE) analyses were performed to derive dislocation density based material constitutive equations for austenite phase by comparing with test results. Subsequently, representative volume elements analyses with periodic boundary conditions were adopted to estimate overall tensile stress-strain curves as well as 0.2% offset yield strengths (YSs) under the virgin and irradiated states. Finally, the effect of irradiated properties on typical RVIs were investigated. As typical results, optimized material parameters related to dislocation density based formulations were revealed, and microscopic stress-strain curves were reasonably comparable with test results. The estimated YS values were compared with the experimental results and corresponded within 9.09%. The overall deformation, stress and strain behaviors of typical RVIs were examined considering estimated properties, of which details and key findings will be discussed.
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Warren, A. W., e Y. B. Guo. "An Experimental Study on Subsurface Mechanical Behavior, Residual Stress, and Microstructure Induced by Process Dynamics in Machining". In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-60021.
Testo completoAbstract (sommario):
Surface integrity of machined components is critical for product performance in service. Process dynamic parameters, such as cutting speed and the changing contact condition between the tool flank face and machined surface, have a significant influence on surface integrity of a machined surface. Due to the very small scale of surface integrity factors on a machined surface, nanoindentation can be used to determine the surface/subsurface mechanical properties. However, the test data may be significantly influenced by machining induced residual stresses, strain hardening, and microstructure changes. The fundamental relationships between residual stress, microstructure, and nanohardness in the machined surface are yet to be understood. Further, it is not clear how to determine residual stress, at least its nature of tensile or compressive, from the nanoindentation data with the presence of complex residual stress state, strain hardening, and microstructure changes. This study focuses on the effects of cutting speed and machining system damping or rigidity (through varying tool flank wear) on subsurface mechanical state and the basic relationships between residual stress, white layer, and nanohardness. A series of nanoindentation tests were conducted to machined samples with distinct surface integrity by hard turning, grinding, and honing. It was found that white layer increases nanohardness and dark layer decreases nanohardness in subsurface, while strain hardening only slightly increases subsurface hardness. The research results indicate that subsurface residual stress can be qualitatively characterized by the load-displacement curve pattern and its parameters such as slope at initial loading, total depth, residual depth, and the ratio of residual depth to total depth. Residual stress would affect a load-displacement curve shape only at onset of yielding. Microstructure changes would make a significant difference on the characteristics of a load-displacement curve, while strain hardening exerts slight influence on the curve characteristics. In addition, the mechanism of residual stress on indentation depth was explained using a Mohr’s circle.
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Karaivanov, Ventzislav G., William S. Slaughter, Sean Siw, Minking K. Chyu e Mary Anne Alvin. "Compressive Creep Testing of Thermal Barrier Coated Nickel-Based Superalloys". In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-23421.
Testo completoAbstract (sommario):
Turbine airfoils have complex geometries and during service operation are subjected to complex loadings. In most publications, results are typically reported for either uniaxial, isothermal tensile creep or for thermal cyclic tests. The former generally provide data for creep of the superalloy and the overall performance, and the later provide data for thermal barrier coating (TBC) spallation as a function of thermally-grown oxide (TGO) thickness, surface roughness, temperature, and thermal mismatch between the layers. Both tests provide valuable data, but little is known about the effect of compressive creep strain on the performance of the superalloy/protective system at elevated temperatures. In conjunction with computational model development, laboratory-scale experimental validation was undertaken to verify the viability of the underlying damage mechanics concepts for the evolution of TBC damage. Nickel-based single-crystal Rene´ N5 coupons that were coated with a ∼150–200 μm MCrAlY bond coat and a ∼200–240 μm 7-YSZ APS topcoat were used in this effort. The coupons were exposed to 900, 1000, and 1100°C, for periods of 100, 300, 1000 and 3000 hours in slotted silicon carbide fixtures. The difference in the coefficients of thermal expansion of the Rene´ N5 substrate and the test fixture introduces thermally induced compressive stress in the coupon samples. Exposed samples were cross-sectioned and evaluated using scanning electron microscopy (SEM). Performance data was collected based on image analysis. Energy-dispersive x-ray (EDX) was employed to study the elemental distribution in the TBC system after exposure. To better understand the loading and failure mechanisms of the coating system under loading conditions, nanoindentation was used to study the mechanical properties (Young’s modulus and hardness) of the components in the TBC system and their evolution with temperature and time. The effect of uniaxial in-plane compressive creep strain on the rate of growth of the thermally grown oxide layer, the time to coating failure in TBC systems, and the evolution in the mechanical properties are presented.
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Maruf, Mahbub Alam, Golam Rakib Mazumder, Souvik Chakraborty, Jeffrey C. Suhling e Pradeep Lall. "Evolution in Lead-Free Solder Alloys Subjected to Both Mechanical Cycling and Aging". In ASME 2023 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/ipack2023-112023.
Testo completoAbstract (sommario):
Abstract Solder joints in electronic packaging often experience failure due to cyclic thermo-mechanical loading. For example, electronic components in the automotive engine compartment or a giant turbine of a power plant may encounter both thermal cycling as well as mechanical cycling due to vibration. At the same time, electronic components can undergo thermal cycling due to frequent power switching, e.g., turning a car engine on and off. Thus, the solder materials used to attach electronic components are often subjected to cyclic stresses and strains due to temperature changes and the CTE mismatches of the assembly materials, as well as due to vibration and other time-varying loadings. In the literature, recent studies by our group have been carried out to examine the mechanical behavior and property evolutions (e.g., modulus, yield stress, ultimate tensile strength, and creep rate) occurring due to either isothermal aging or due to isothermal mechanical cycling. In the case of aging, microstructure changes are the primary reason for changes in the mechanical response. In the case of mechanical cycling, both microstructural evolution and damage accumulation (e.g. microcrack growth) lead to the observed changes. Currently, there are no prior investigations on the effects of both isothermal aging and mechanical cycling on the mechanical property and microstructural evolution of lead-free solder alloys. In this study, we have evaluated the changes in mechanical properties and microstructure that occur due to mechanical cycling followed by isothermal aging at high temperature. Uniaxial samples of SAC305 lead-free solder alloy were first prepared by solidification in glass tubes under a controlled reflow profile. The samples were first mechanically cycled under strain control for various durations (e.g., 0, 50, 100, 200, 300 cycles), and then subsequently aged for 20 days at T = 125 °C. All of the preconditioned specimens were then subjected to nanoindentation testing to evaluate mechanical properties. Results for the various tests were compared to characterize the effects of combined effects of aging and mechanical cycling on the deterioration of the elastic modulus, hardness, and creep properties relative to the results for pristine specimens. As expected, exposure to both cycling and aging greatly influenced the results, with the samples that were cycled 300 times followed by aging showing the greatest degradations. Optical microscopy was also used to evaluate the microstructural evolution which demonstrates microstructural coarsening occurred in the samples due to the combination of mechanical cycling aging.
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Breedlove, Evan L., Mark T. Gibson, Aaron T. Hedegaard e Emilie L. Rexeisen. "Evaluation of Dynamic Mechanical Test Methods". In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65742.
Testo completoAbstract (sommario):
Dynamic mechanical properties are critical in the evaluation of materials with viscoelastic behavior. Various techniques, including dynamic mechanical analysis (DMA), rheology, nanoindentation, and others have been developed for this purpose and typically report complex modulus. Each of these techniques has strengths and weaknesses depending on sample geometry and length scale, mechanical properties, and skill of the user. In many industry applications, techniques may also be blindly applied according to a standard procedure without optimization for a specific sample. This can pose challenges for correct characterization of novel materials, and some techniques are more robust to agnostic application than others. A relative assessment of dynamic mechanical techniques is important when considering the appropriate technique to use to characterize a material. It also has bearing on organizations with limited resources that must strategically select one or two capabilities to meet as broad a set of materials as possible. The purpose of this study was to evaluate the measurement characteristics (e.g., precision and bias) of a selection of six dynamic mechanical test methods on a range of polymeric materials. Such a comprehensive comparison of dynamic mechanical testing methods was not identified in the literature. We also considered other technical characteristics of the techniques that influence their usability and strategic value to a laboratory and introduce a novel use of the House of Quality method to systematically compare measurement techniques. The selected methods spanned a range of length scales, frequency ranges, and prevalence of use. DMA, rheology, and oscillatory loading using a servohydraulic tensile tester were evaluated as traditional bulk techniques. Determination of complex modulus by beam vibration was also considered as a bulk technique. At a small length scale, both an oscillatory nanoindentation method and AFM were evaluated. Each method was employed to evaluate samples of polycarbonate, polypropylene, amorphous PET, and semi-crystalline PET. A measurement systems analysis (MSA) based on the ANOVA methods outlined in ASTM E2782 was conducted using storage modulus data obtained at 1 Hz. Additional correlations over a range of frequencies were tested between rheology/DMA and the remaining methods. Note that no attempts were made to optimize data collection for the test specimens. Rather, typical test methods were applied in order to simulate the type of results that would be expected in typical industrial characterization of materials. Data indicated low levels of repeatability error (<5%) for DMA, rheology, and nanoindentation. Biases were material dependent, indicating nonlinearity in the measurement systems. Nanoindentation and AFM results differed from the other techniques for PET samples, where anisotropy is believed to have affected in-plane versus out-of-plane measurements. Tensile-tester based results were generally poor and were determined to be related to the controllability of the actuator relative to the size of test specimens. The vibrations-based test method showed good agreement with time-temperature superposition determined properties from DMA. This result is particularly interesting since the vibrations technique directly accesses higher frequency responses and does not rely on time-temperature superposition, which is not suitable for all materials. MSA results were subsequently evaluated along with other technical attributes of the instruments using the House of Quality method. Technical attributes were weighted against a set of “user demands” that reflect the qualitative expectations often placed on measurement systems. Based on this analysis, we determined that DMA and rheology provide the broadest capability while remaining robust and easy to use. Other techniques, such as nanoindentation and vibrations, have unique qualities that fulfill niche applications where DMA and rheology are not suitable. This analysis provides an industry-relevant evaluation of measurement techniques and demonstrates a framework for evaluating the capabilities of analytical equipment relative to organizational needs.
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Bũrkle, G., H. J. Fecht, A. Sagel e C. Wanke. "Dynamical Mechanical Analysis of the Mechanical Properties of Al- and Fe-Based Thermal Spray Coatings". In ITSC2001, a cura di Christopher C. Berndt, Khiam A. Khor e Erich F. Lugscheider. ASM International, 2001. http://dx.doi.org/10.31399/asm.cp.itsc2001p0999.
Testo completoAbstract (sommario):
Abstract Static mechanical properties such as Young's Modulus, Yield Stress and Ultimate Tensile Strength and especially fatigue behavior are important material properties for thermal spray coatings and their industrial application in automotive and aerospace industry. The static and dynamic mechanical properties of Al-Si, Al-Sn, Fe-Cr and Fe-Cr-B based coating materials deposited by APS, TWAS and HVOF were investigated by nanoindentation and in a three point bending test using DMA (Dynamic Mechanical Analysis). This method permits the determination of pure coating material static and dynamic mechanical properties without substrate influence over a wide temperature range. In this investigation all measurements were carried out at room temperature. The DMA method was verified by comparison of Young's modulus to those obtained by nanoindentation.
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Schoeller, Harry, Shubhra Bansal, Aaron Knobloch, David Shaddock e Junghyun Cho. "Constitutive Relations of High Temperature Solders". In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42215.
Testo completoAbstract (sommario):
This study focuses on microelectronic package design for the oil and natural gas drilling of wells with depths in excess of 20,000 ft, where package temperatures can exceed 204°C. At these high temperatures, solder interconnect sites are subject to fatigue and creep failures due to the stress generated by the thermal expansion mismatch between various components in the package. Typically this phenomenon is modeled by finite element analysis (FEA) to predict the number of cycles to failure. To ensure meaningful model results, however, accurate time and temperature-dependent mechanical properties are needed. This study examines five solders suitable for high temperature: 90Pb-10Sn, 95Sn-5Sb, 92.5Pb-5Sn-2.5Ag, 95Pb-5In, and 93Pb-3Sn-2Ag-2In. Uniaxial tension tests of the solder wires are carried out on a MTS servohydraulic machine using wedge grips. To evaluate the time-dependence on deformation, a strain rate study was carried out at 0.5%/sec, 1%/sec, and 5%/sec. Nanoindentation of solder wire is performed and compared to the corresponding solder wires tested through uniaxial tension tests. Dynamic nanoindentation through continuous stiffness measurement is performed on the wires to obtain the indentation data less sensitive to creep of the material, as well as to assess the effect of indentation depth on elastic modulus for each solder. One purpose of nanoindentation testing is to determine its suitability for the mechanical testing of soft solders. Mechanical properties obtained from these tests will be used in future modeling studies to estimate the cyclic fatigue life of these solders under thermal loading.
Rapporti di organizzazioni sul tema "Tensile tests. nanoindentation"
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Weiss, Charles, William McGinley, Bradford Songer, Madeline Kuchinski e Frank Kuchinski. Performance of active porcelain enamel coated fibers for fiber-reinforced concrete : the performance of active porcelain enamel coatings for fiber-reinforced concrete and fiber tests at the University of Louisville. Engineer Research and Development Center (U.S.), maggio 2021. http://dx.doi.org/10.21079/11681/40683.
Testo completoAbstract (sommario):
A patented active porcelain enamel coating improves both the bond between the concrete and steel reinforcement as well as its corrosion resistance. A Small Business Innovation Research (SBIR) program to develop a commercial method for production of porcelain-coated fibers was developed in 2015. Market potential of this technology with its steel/concrete bond improvements and corrosion protection suggests that it can compete with other fiber reinforcing systems, with improvements in performance, durability, and cost, especially as compared to smooth fibers incorporated into concrete slabs and beams. Preliminary testing in a Phase 1 SBIR investigation indicated that active ceramic coatings on small diameter wire significantly improved the bond between the wires and the concrete to the point that the wires achieved yield before pullout without affecting the strength of the wire. As part of an SBIR Phase 2 effort, the University of Louisville under contract for Ceramics, Composites and Coatings Inc., proposed an investigation to evaluate active enamel-coated steel fibers in typical concrete applications and in masonry grouts in both tension and compression. Evaluation of the effect of the incorporation of coated fibers into Ultra-High Performance Concrete (UHPC) was examined using flexural and compressive strength testing as well as through nanoindentation.