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Artykuły w czasopismach na temat "Metallic Glass Specimens"
1
Wu, F. F., Z. F. Zhang i S. X. Mao. "Compressive properties of bulk metallic glass with small aspect ratio". Journal of Materials Research 22, nr 2 (luty 2007): 501–7. http://dx.doi.org/10.1557/jmr.2007.0064.
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The quasi-static compressive deformation behavior of a Vitreloy 1 bulk metallic glass (BMG) with an aspect ratio of 0.25 was investigated. It is found that the friction and the confinement at the specimen–loading platen interface will cause the dramatic increase in the compressive load, leading to higher compressive strength. In particular, the BMG specimens show great plastic-deformation ability, and plenty of interacted, deflected, wavy, or branched shear bands were observed on the surfaces after plastic deformation. The formation of the strongly interacted, deflected, wavy, or branched shear bands can be attributed to the triaxial stress state in the glassy specimens with a very small aspect ratio.
2
Zhang, H., L. Z. Liu, Z. F. Zhang, K. Q. Qiu, X. F. Pan, H. F. Zhang i Z. G. Wang. "Deformation and fracture behavior of tungsten fiber-reinforced bulk metallic glass composite subjected to transverse loading". Journal of Materials Research 21, nr 6 (1.06.2006): 1375–84. http://dx.doi.org/10.1557/jmr.2006.0169.
Pełny tekst źródłaStreszczenie:
Deformation and fracture behavior of Zr41.25Ti13.75Ni10Cu12.5Be22.5 bulk metallic glass and its composite containing transverse tungsten fibers in compression were investigated. The monolithic metallic glass and the tungsten fiber composite specimens with aspect ratios of 2 and 1 are shown to have essentially the same ultimate strength under compression. The damage processes in the bulk metallic glass composite consisted of fiber cracking, followed by initiation of shear band in the glassy matrix mainly from the impingement of the fiber crack on the fiber/matrix interface. The site of the shear band initiation in the matrix is consistent with the prediction of finite element modeling. Evidence is present that the tungsten fiber can resist the propagation of the shear band in the glassy matrix. However, the compressive strain to failure substantially decreased in the present composite compared with the composites containing longitudinal tungsten fibers. Finally, the two composite specimens fractured in a shear mode and almost all the tungsten fibers contained cracks.
3
Nakai, Yoshikazu, Naoki Sei i Bok Key Kim. "Notched Fatigue of Zr-Based Bulk Metallic Glass". Key Engineering Materials 345-346 (sierpień 2007): 259–62. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.259.
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In the present study, fatigue tests of sharp-notched Zr-based bulk metallic glass (BGM), were conducted under fully reversed cyclic bending, and the fatigue crack initiation mechanisms were clarified by using AFM. The fracture surface was also observed to examine the crack propagation mechanism. The fatigue notch factor was 2.0, while the elastic stress concentration factor is 2.7. From the macroscopic observations of fractured specimen, either tension mode or shear mode fracture morphologies were observed. Either in smooth specimens or notched specimens, no prodigious sign of crack initiation were observed, i.e., fatigue cracks were initiated from shear bands those were formed just before the crack initiation.
4
Lu, Tong, Song Ling Liu, Yong Hao Sun, Wei-Hua Wang i Ming-Xiang Pan. "A Free-Volume Model for Thermal Expansion of Metallic Glass". Chinese Physics Letters 39, nr 3 (1.03.2022): 036401. http://dx.doi.org/10.1088/0256-307x/39/3/036401.
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Many mechanical, thermal and transport behaviors of polymers and metallic glasses are interpreted by the free-volume model, whereas their applications on thermal expansion behaviors of glasses is rarely seen. Metallic glass has a range of glassy states depending on cooling rate, making their coefficients of thermal expansion vary with the glassy states. Anharmonicity in the interatomic potential is often used to explain different coefficients of thermal expansion in crystalline metals or in different metallic-glass compositions. However, it is unclear how to quantify the change of anharmonicity in the various states of metallic glass of the same composition and to connect it with coefficient of thermal expansion. In the present work, isothermal annealing is applied, and the dimensional changes are measured for La62Al14Cu11.7Ag2.3Ni5Co5 and Zr52.5Cu17.9Ni14.6Al10Ti5 metallic glasses, from which changes in density and the coefficients of thermal expansion of the specimens are both recorded. The coefficients of thermal expansion linearly decrease with densification reflecting the role of free volume in thermal expansion. Free volume is found to have not only volume but also entity with an effective coefficient of thermal expansion similar to that of gases. Therefore, the local regions containing free volume inside the metallic glass are gas-like instead of liquid-like in terms of thermal expansion behaviors.
5
He, Tianbing, Nevaf Ciftci, Volker Uhlenwinkel i Sergio Scudino. "Synthesis of Bulk Zr48Cu36Al8Ag8 Metallic Glass by Hot Pressing of Amorphous Powders". Journal of Manufacturing and Materials Processing 5, nr 1 (9.03.2021): 23. http://dx.doi.org/10.3390/jmmp5010023.
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The critical cooling rate necessary for glass formation via melt solidification poses inherent constraints on sample size using conventional casting techniques. This drawback can be overcome by pressure-assisted sintering of metallic glass powders at temperatures above the glass transition, where the material shows viscous-flow behavior. Partial crystallization during sintering usually exacerbates the inherent brittleness of metallic glasses and thus needs to be avoided. In order to achieve high density of the bulk specimens while avoiding (or minimizing) crystallization, the optimal combination between low viscosity and long incubation time for crystallization must be identified. Here, by carefully selecting the time–temperature window for powder consolidation, we synthesized highly dense Zr48Cu36Ag8Al8 bulk metallic glass (BMG) with mechanical properties comparable with its cast counterpart. The larger ZrCu-based BMG specimens fabricated in this work could then be post-processed by flash-annealing, offering the possibility to fabricate monolithic metallic glasses and glass–matrix composites with enhanced room-temperature plastic deformation.
6
Saotome, Yasunori, Suguru Okaniwa, Hisamichi Kimura i Akihisa Inoue. "Superplastic Nanoforging of Pt-Based Metallic Glass with Dies of Zr-BMG and Glassy Carbon Fabricated by Focused Ion Beam". Materials Science Forum 539-543 (marzec 2007): 2088–93. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.2088.
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This paper introduces a technique for fabricating nano-structures through super plastic nano-forging of metallic glass using nano-scale dies that are fabricated by a focused-ion beam (FIB). FIB-machining characteristics of glassy carbon and Zr-based metallic glass have been studied and are useful for fabricating nano-scale dies because of the isotropic homogeneity of their amorphous structures. We used the dies to nano-forge Pt48.75Pd9.75Cu19.5P22 metallic glass. The thin foil specimens were heated in a small furnace and compressively loaded in a small vacuum chamber. Dies, a die-forged 1μm-diameter micro-gear, and both 800 and 400nm periodic nano-structures for optical applications were demonstrated. We observed the effects of thermal expansion and contact angle between the working material and the die materials on nano-formability. Metallic glasses are highly useful as materials for nano-imprinting and as die materials for FIB nano-machining.
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Bruck, H. A., A. J. Rosakis i W. L. Johnson. "The dynamic compressive behavior of beryllium bearing bulk metallic glasses". Journal of Materials Research 11, nr 2 (luty 1996): 503–11. http://dx.doi.org/10.1557/jmr.1996.0060.
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In 1993, a new beryllium bearing bulk metallic glass with the nominal composition Zr41.25Ti13.75Cu12.5Ni10Be22.5 was discovered at Caltech. This metallic glass can be cast as cylindrical rods as large as 16 mm in diameter, which permitted specimens to be fabricated with geometries suitable for dynamic testing. For the first time, the dynamic compressive yield behavior of a metallic glass was characterized at strain rates of 102 to 104/s by using the split Hopkinson pressure bar. A high-speed infrared thermal detector was also used to determine if adiabatic heating occurred during dynamic deformation of the metallic glass. From these tests it appears that the yield stress of the metallic glass is insensitive to strain rate and no adiabatic heating occurs before yielding.
8
Yang, Yu-Hang, Jun Yi, Na Yang, Wen Liang, Hao-Ran Huang, Bo Huang, Yan-Dong Jia, Xi-Lei Bian i Gang Wang. "Tension-Tension Fatigue Behavior of High-Toughness Zr61Ti2Cu25Al12 Bulk Metallic Glass". Materials 14, nr 11 (25.05.2021): 2815. http://dx.doi.org/10.3390/ma14112815.
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Bulk metallic glasses have application potential in engineering structures due to their exceptional strength and fracture toughness. Their fatigue resistance is very important for the application as well. We report the tension-tension fatigue damage behavior of a Zr61Ti2Cu25Al12 bulk metallic glass, which has the highest fracture toughness among BMGs. The Zr61Ti2Cu25Al12 glass exhibits a tension-tension fatigue endurance limit of 195 MPa, which is higher than that of high-toughness steels. The fracture morphology of the specimens depends on the applied stress amplitude. We found flocks of shear bands, which were perpendicular to the loading direction, on the surface of the fatigue test specimens with stress amplitude higher than the fatigue limit of the glass. The fatigue cracking of the glass initiated from a shear band in a shear band flock. Our work demonstrated that the Zr61Ti2Cu25Al12 glass is a competitive structural material and shed light on improving the fatigue resistance of bulk metallic glasses.
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Kuroda, Toshio, Kenji Ikeuchi, Masahiro Shimada, Akihisa Inoue i Hisamichi Kimura. "Micro Flash Welding of Super Duplex Stainless Steel with Zr Metallic Glass Insert". Materials Science Forum 580-582 (czerwiec 2008): 53–56. http://dx.doi.org/10.4028/www.scientific.net/msf.580-582.53.
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Micro flash butt welding of super duplex stainless steel with Zr-based metallic glass insert was carried out using the temperature controlling system. Zr55Cu30Ni5Al10 of Zr-based metallic glass with thickness of 0.05mm and Zr metal with thickness of 0.1mm and 0.5 mm were used as the insert materials, in order to improve weldability. The specimens were mounted on the dies using a Gleeble thermal simulator, and then, flash butt welding was made. After welding, Zrbased metallic glass insert became much thinner than Zr metal insert. The super-cooled liquid in the interface protruded outside due to the superplastic deformation. The formation of the protrusion discharged the oxide films on the butting surfaces and contact surface; resulting in metallurgical bonding through the fresh surfaces. The Fe-Zr metallic compound for Zr-based metallic glass insert was hardly observed. The micro flash butt welding with metallic glass insert was successfully accomplished for super duplex stainless steel.
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Wang, Jin Xiang, Xiao Li Zhang, Nan Zhou i Zheng Zhao. "Explosive Compaction of Metallic Glass Particles Reinforced Aluminium Matrix Composites". Advanced Materials Research 189-193 (luty 2011): 2472–76. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.2472.
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In this paper the metallic glass particles reinforced aluminium matrix composites without obvious defects were obtained successfully by explosive compaction of mixed powders. The mass fraction of the amorphous phase is 10%, 15% and 20% respectively in the specimens. The scaning electric microscope micrographs of the composites show that the metallic glass particles are uniformly distributed in the matrix. The x-ray diffraction and differential thermal analysis of the composite specimens show that the amorphous phase is maintained in the composites without crystallization during the compaction. Finally the influences of macro-temperature rise and micro-heat transfer on the crystallization were analyzed.
Rozprawy doktorskie na temat "Metallic Glass Specimens"
1
Singh, Indrasen. "Continuum Analysis of Cavitation Induced Failure and Tensile Deformation Response of Metallic Glasses & Nanoglasses". Thesis, 2016. https://etd.iisc.ac.in/handle/2005/4890.
Pełny tekst źródłaStreszczenie:
Metallic glasses (MGs), which are metals solidified in an amorphous state, have shown attractive
mechanical properties such as high strength (up to 5 GPa), yield strain (around
2%) and good corrosion resistance. They exhibit heterogeneous plastic flow by formation
of shear bands (SBs) at temperatures well below the glass transition temperature.
However, they can be very brittle with KIc ∼ 1 - 15 MPa
√
m or very tough (KIc ∼ 80
MPa
√
m). Experiments and MD simulations suggest that failure in the brittle MGs occurs
by cavitation with little shear banding and can be traced to nanoscale fluctuations in
atomic density. Also, notwithstanding their high KIc, MG samples lack tensile ductility
and fail catastrophically by crack propagation in a dominant SB. However, nano-sized
MG samples and a novel architecture called as nanoglass (NG) composed of nano-grains
of MGs separated by fine free volume rich interfaces do exhibit tensile ductility. Relatively
few continuum simulations have been undertaken to understand the deformation
and fracture behavior of MGs and NGs from a mechanics standpoint. Therefore, continuum
finite element analysis of cavitation and cavitation induced fracture in brittle
MGs are performed in this work. In addition, tensile deformation behavior of nano-scale
notched MG and NG samples are analyzed.
Brittle MGs are modeled as heterogeneous elastic-plastic solid containing doubly
periodic distribution of weak zones with lower yield strength. The presence of the weak
zones mimics the density/strength fluctuation in brittle MGs as observed in experiments
and atomistic simulations. Finite element simulations are performed by subjecting a
square unit cell containing a circular weak zone to different (biaxiality) stress ratios
under 2D plane strain conditions. A tiny void is introduced in the weak zone to trigger
cavitation. The results show that the critical hydrostatic stress at cavitation is reduced
due to the presence of the weak zones and is governed by yield properties of the weak
zone and the prevailing stress state. Moreover, unlike in a homogeneous plastic solid,
the cavitation stress of the heterogeneous aggregate does not reduce appreciably as the
stress ratio decreases from unity when the yield strength of the weak zone is low. The
volume fraction of the weak zones and stress ratio influence the nature of cavitation
bifurcation. This includes the possibility of snap cavitation wherein a void of finite size
suddenly forms in the intact material which does not happen in a homogeneous plastic
solid.
Further, continuum simulations of crack initiation under mode-I plane strain, small
scale yielding conditions in a heterogeneous elastic-plastic solid having a distribution
of weak zones are performed. The results show that a three-step process is involved
in the catastrophic fracture observed in brittle MGs. First, cavities nucleate in weak
zones ahead of the crack tip and start growing rapidly. Secondly, curved shear bands
form linking the current crack tip with the nearby cavity. Thirdly, as plastic strain
and free volume accumulate within these shear bands, failure takes place facilitating
further extension of the crack. The proposed fracture mechanism explains the formation
of nano-corrugations in brittle MGs. The results also predict a correlation between
notched fracture toughness and Poisson’s ratio and brittle-ductile transition which is
qualitatively similar to that observed in experiments.
the deformation behavior of nano-sized notched MG samples subjected to plane strain
tensile loading is modeled through finite element simulations using a non-local plasticity
theory for MGs. The results show that a plastic zone first develops around the notch
root and grows to a critical size before a dominant shear band emanates from this zone
that would lead to failure. The SB width and the saturation notch root plastic zone size
scales with an intrinsic material length lc associated with interaction stress between flow
defecrs. Also, the ratio of the ligament length to saturation plastic zone size governs the
transition from shear banding to necking.
The deformation behaviour of NGs subjected to plane strain tensile loading is investigated
through finite element simulations using the above non-local plasticity theory. It
is found that the ratio of the material length lc to nano-grain size governs the deformation
behavior of NGs. Also, SB width scales in same manner with lc both in MG and
NG specimens and moderate changes in specimen size have little effect on mechanical
response of NGs.
Części książek na temat "Metallic Glass Specimens"
1
Narasimhan, R., Tanmay Dutta i I. Singh. "Plastic Deformation and Failure Mechanisms in Notched Nano-Scale Metallic Glass Specimens". W Structural Integrity, 329–30. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-91989-8_71.
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Shin, Hyung Seop, Ki Hyun Kim, Young Jin Jung i Dong Kyun Ko. "Impact Fracture Behavior of Zr-Based Bulk Metallic Glass Using Subsize Charpy Specimen". W Key Engineering Materials, 1356–64. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-978-4.1356.
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W. Kim, Yong. "Thermal Tuning of Thermophysical Properties of Single Cu-Ni Alloy". W Copper - From the Mineral to the Final Application [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.108266.
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The great majority of metallic materials in use are not single crystals but disordered. We model such a material specimen as being composed of nanoclusters, each cluster being a small mutually interacting cluster of atoms. In this modeling, a material specimen is then treated as a mixture of nanocrystalline and glassy-state atoms. If we define the degree of crystallinity of the object by the probability that an atom is a member of a crystallite existing within the specimen, the probability would be smaller than unity. Structural disorder in such metallic alloys affects thermophysical properties of the alloy specimen in myriad ways. Transport properties in turn impact material utilization in significant ways to the extent that the specimen could behave as possessing completely different alloy properties. This approach to changing alloy properties can serve useful purposes. We show how one might approach such modification of alloy properties without changing alloy composition with a sample of copper-nickel alloy.
Streszczenia konferencji na temat "Metallic Glass Specimens"
1
Abd El-Latief, Mahmoud E., Mostafa Shazly i Yehia Bahei-El-Din. "Evaluation of the Mechanical Properties of Repaired Composite Panels Using Resin Re-Infusion Process". W ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23448.
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Abstract Glass Fiber Reinforced Plastics (GFRP) have been used in many fields such as aerospace, automotive and wind energy sectors. During their manufacturing processes, some defects such as dry spots and air pockets may develop in impregnated fabric, especially, when metallic inserts are used. To evaluate the interface between parent and repaired parts, an experimental study is performed to investigate its effect on the mechanical properties and structural integrity. To compare the response of the re-infused and intact samples, several tensile and bending tests were performed for uniaxial glass reinforcing fabric with tailored orientation for the interface between the intact and repaired regions. The results showed that for the tensile tests, repaired specimens with interfaces having 90° and 45° orientations w.r.t. loading direction were able to recover 80% and 73%, respectively, from the tensile strength of samples produced by vacuum infusion technique. However, for bending tests, the flexural strength was recovered by almost 90% and 72% for both interfaces, respectively. Based on visual inspection, each type of tested specimen has a typical dominant failure mode. For re-infused samples, the properties of the parent and repaired laminates determine the failure location.
2
Cole, Daniel P., i Ed M. Habtour. "Improved Understanding of Damage Precursors Through Local Mechanical Characterization". W ASME 2015 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/smasis2015-8822.
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We report on the use of local mechanical characterization techniques for the understanding of structural damage precursors in various material systems. Instrumented indentation and atomic force microscopy (AFM) were used to characterize local damage in: (1) fatigued metallic beams subject to non-linear vibration, (2) individual polymer and glass microfibers, and (3) additive manufactured thermoplastics. Indentation studies of the fatigued metallic beams showed a compliance effect of up to 40% in relatively highly stressed regions. An approved fiber mounting technique allowed for indentation of unmodified surfaces of single microfibers, while AFM modulus maps of the fibers reveal local regions of relative compliance. Local mechanical tests of 3-D printed acrylonitrile butadiene styrene specimens revealed a variation in properties between printed beads and bead-bead interfaces. The nano-/micro-scale techniques developed in the present study provide a framework for understanding how damage precursors may affect processing-structure-property relationships in present and future structural aerospace materials.
3
PERNA, A. S. "Machining of hybrid structures produced through cold spray technology: A preliminary study". W Material Forming. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902479-187.
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Abstract. Cold spray is a recently developed manufacturing technology for creating metallic layers on a variety of materials. Metallic particles are accelerated and strike the target surface using a pressurized gas flowing at supersonic speeds. In the last years, cold spray has gained increasing interest in different industrial scenarios, in particular, in the aerospace sector. Given the many fields of application, the need to understand how coated substrates behave when it is necessary to carry out machining operations arises. In this work, low-pressure cold spray equipment was employed to produce metal coatings on epoxy-based glass fibre-reinforced substrates optimized for cold spray deposition employing a layer of polypropylene on the composite surface. An automatic multi-purpose machine was used to drill 4mm diameter holes in the coated specimens considering the rotational speed fixed and varying the feed rate. The machined areas were then analyzed to assess the surface quality of the drilled holes and the burr morphology, considering different feed rate values and different entry surface of the drill-bit.
4
Hosur, M. V., U. K. Vaidya, A. Haque, M. Kulkarni, R. Kulkarni i S. Jeelani. "Evaluation of Ballistic Impact Damage of Fiber Reinforced Plastic Laminates Bonded by Polycarbonate Facesheets". W ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0210.
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Abstract Fiber reinforced polymer matrix composites are being increasingly used in many applications including aerospace, armored vehicle, marine and sporting industries. They provide the advantage of high specific stiffness and specific strength as compared to conventional metallic materials. However, they are well known by their vulnerability to threats like impact loading that occurs normally in the transverse direction. Hence, there is a need to improve the damage resistance in the transverse direction at minimum weight penalty. In this current investigations, a two component material system made of fiber reinforced laminates bonded by a polycarbonate facesheet was studied. Laminates made of both unidirectional graphite/epoxy prepregs and S2-glass twill weave woven fabric/SC-15 resin systems were used in the study. Specimens of size 304.8 × 304.8 mm were made using different thickness ratios of facesheet and the backing laminate. Three different thicknesses of s2-glass laminates (3.17, 4.31 and 5.71 mm) were used to bond to two polycarbonate sheets of thickness 2.54 and 3.17 mm each. Similarly, three different thickness of graphite/epoxy laminates (2.05, 3.75 and 7.62 mm) were used to bond to polycarbonate facesheet of thickness 1.00, 3.175, and 4.30 mm. The ballistic tests are performed with a space test setup using fragment simulating projectiles(FSP). The ensuing damage was evaluated using ultrasonic C-scan technique using pule-echo immersion method.
5
Zhao, Liuxian, Lingyu Yu, Mattieu Gresil, Michael Sutton i Siming Guo. "Electromechanical Impedance Modeling for Structural Health Monitoring". W ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/smasis2012-8094.
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Electromechanical impedance (EMI) method is an effective and powerful technique in structural health monitoring (SHM) which couples the mechanical impedance of host structure with the electrical impedance measured at the piezoelectric wafer active sensor (PWAS) transducer terminals. Due to the electromechanical coupling in piezoelectric materials, changes in structural mechanical impedance are reflected in the electrical impedance measured at the PWAS. Therefore, the structural mechanical resonances are reflected in a virtually identical spectrum of peaks and valleys in the real part of the measured EMI. Multi-physics based finite element method (MP-FEM) has been widely used for the analysis of piezoelectric materials and structures. It uses finite elements taking both electrical and mechanical DOF’s into consideration, which allows good differentiation of complicated structural geometries and damaged areas. In this paper, MP-FEM was then used to simulate PWAS EMI for the goal of SHM. EMI of free PWAS was first simulated and compared with experimental result. Then the constrained PWAS was studied. EMI of both metallic and glass fiber composite materials were simulated. The first case is the constrained PWAS on aluminum beam with various dimensions. The second case studies the sensitivity range of the EMI approach for damage detection on aluminum beam using a set of specimens with cracks at different locations. In the third case, structural damping effects were also studied in this paper.. Our results have also shown that the imaginary part of the impedance and admittance can be used for sensor self-diagnosis.
6
Sunny, George P., Vikas Prakash i John J. Lewandowski. "Effects of Annealing on Dynamic Behavior of a Bulk Metallic Glass". W ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-83016.
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Bulk metallic glasses are excellent candidate materials for integral armor because of their high strength and large elastic strain. Also, annealed glasses exhibit higher yield strengths than their fully amorphous counterparts. Therefore, the dynamic behavior of an annealed bulk metallic glass, Zr41.25Ti13.75Ni10Cu12.5Be22.5, was investigated in this study. A Split-Hopkinson Pressure Bar (SHPB) was employed to determine the stress-strain response at strain rates varying from 500/s-2000/s for the annealed glass. Also, a high-speed camera was utilized to obtain in-situ video of the specimen during the deformation process. These results were then compared to similar tests on the fully amorphous material. Finally, a new specimen design and experimental setup was proposed to promote accurate measurements from SHPB tests. During dynamic loading, the strain to failure increased as the strain-rate was increased, and the changes in strain-rate produced a larger effect than that of the annealing treatment on the failure strain. Maximum stresses were generally higher for the annealed glass, although there was some scatter. Finally, while an instability formed a dominant shear band for the as-received material, extensive fragmentation characterized the deformation after formation of an initial crack.
7
Sunny, George P., Vikas Prakash i John P. Lewandowski. "Results From a Novel Insert Design for High Strain-Rate Compression of a Bulk Metallic Glass". W ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-15414.
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Liquidmetal-1 (LM-1, Zr41.25Ti13.75Cu12.5Ni10Be22.5) is a bulk metallic glass that can be processed in large thicknesses (e.g. 10 mm) because of its low critical cooling rate (e.g. 1 K/s). Like other bulk metallic glasses, this material exhibits near theoretical strength and large elastic strains (~2%) under quasi-static loading conditions. In this work, the Split-Hopkinson Pressure Bar (SHPB) was employed to perform high strain-rate compression tests on annealed LM-1. An ultrahigh-speed camera was also employed to perform in-situ video of the deformation process of the experiments, and the macroscopic fracture behavior was examined after testing. In addition, a new insert design was developed to reduce the effects of stress concentrations on the specimen. SHPB testing, combined with in-situ video, was performed on as-cast LM-1 using this new experimental configuration to determine the failure modes. The results of these experiments are compared to previous results to understand better the effects of stress concentration on high strain-rate behavior of bulk metallic glass.
8
Cipoletti, D. E., C. W. Ziemian, W. J. Wright, K. V. Haile, M. N. Okwara, K. A. Hetherington i D. J. Helfritch. "Critical Velocity Window for the Deposition of Iron-Based Metallic Glass Particles Using Cold Spray". W ITSC2015, redaktorzy A. Agarwal, G. Bolelli, A. Concustell, Y. C. Lau, A. McDonald, F. L. Toma, E. Turunen i C. A. Widener. ASM International, 2015. http://dx.doi.org/10.31399/asm.cp.itsc2015p0273.
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Abstract This study investigates the feasibility of forming amorphous iron-based coatings using the cold spray deposition process. Splat tests of cold-sprayed SAM1651 (Fe48Mo14Cr15Y2C15B6 at.%) particles impacting a mild steel substrate were performed using varying gas temperatures and particle diameters. Specimen inspection by scanning electron microscopy revealed splat morphologies that varied from well-adhered particles to substrate craters formed by rebounded particles. Particle flow was analyzed using a finite element model, and impact conditions were predicted using an experimentally validated analytical model, in empirically generating a temperature/velocity window of successful particle deposition as a framework for ongoing work on the formation of cold-sprayed SAM1651 coatings. The results indicate that the unique characteristics of the cold spray process offer a promising means for the formation of metallic glass coatings that successfully retain the amorphous structure, as well as the superior corrosion and wear resistant properties of the feedstock powder.
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Ramakrishnan, S. "Comparative Study on the Behavior of Fiber Reinforced Concrete". W Sustainable Materials and Smart Practices. Materials Research Forum LLC, 2022. http://dx.doi.org/10.21741/9781644901953-13.
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Abstract. Next to water, concrete is the most consumed material in the world. In the construction industries, concrete is a basic material used for high compressive strength, durable, fire resistant but has low tensile strength. This experimental study aimed to investigation the compressive, tensile and flexural strength of the concrete reinforced with three different fibers. Comparative study has been made between metallic: steel fibers and nonmetallic: glass and carbon fiber reinforced concrete. Fibers were used in concrete with fractions of 0%, 0.5%, 1%, 1.5%, 2% and 2.5% by volume of cement in M20 grade of concrete. In this paper, the behavior of cube, cylinder and prism specimen of fiber reinforced concrete (FRC) were deliberated. Addition of fiber in concrete were increased the basic mechanical properties of concrete increases. The steel fiber reinforced concrete attains higher compressive, flexural and tensile strength than concrete with carbon fiber and glass fiber. Carbon fibered concrete attained higher flexural and tensile strength than glass fibered concrete.
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Lane, Kerry V., Nathan K. Yasuda, Michael E. Lo, Emily R. Mather i Frank J. Shih. "Experimental Characterization of Low Velocity Impact Energy Dissipation in Sandwich Composites With Porous Cores With Tailored Structure and Morphology". W ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-67901.
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The impact performance of several porous polymeric and metallic foam core sandwich composite systems were evaluated for their suitability for protecting vehicle occupants in the event of a low velocity impact. The material systems evaluated were glass/phenolic face sheets reinforced with Nomax honeycomb core, cross-ply carbon-fiber face sheets reinforced with aluminum honeycomb cores of different cell sizes, and aluminum metallic foam cores of different cell sizes. Lastly, an exploratory study using an extrusion type 3D-printed polystyrene foam structure that customized pore size, pore distribution were undertaken. The peak load and energy dissipation of the composite materials were experimentally measured. An instrumented large semispherical impactor (48 mm diameter) applied loads at constant strain rate on the order of 0.1 m/sec to a 50 mm × 50 mm coupon sized composite specimen with varying thicknesses. The impact damage to materials were also visually examined. The current material system used for some interior components (glass/phenolic face sheets reinforced with Nomax honeycomb core) reaches a maximum load in a small time duration and displacement, causing catastrophic local crushing and delamination events. It is expected that the failure can be spread out with these alternative material systems with varying pore size distribution so that the energy dissipation can be accomplished with a lower peak force to improve occupant safety.